Authors
- Carol Reese, Retired Extension Specialist, University of Tennessee
- David Lockwood, Retired Professor & Extension Specialist, University of Tennessee
- Natalie Bumgarner, Associate Professor & Extension Specialist, University of Tennessee
Growing fruit in your own landscape or garden can be an excellent way to produce food. The key to success is understanding certain important decisions to be made and essential tasks to be carried out. Each of these decisions and tasks can be considered part of a puzzle. If all the pieces of the puzzle are present and in their proper place, the results will most likely be positive. Neglecting any of these items, on the other hand, will jeopardize productivity and longevity.
As interest in home fruit growing and edible landscapes increases, Extension Master Gardeners are likely to receive many questions. Understanding the key aspects of fruit production can help us address our own questions and those of others, enabling Master Gardeners to support success in their own gardens and the gardens of those they assist throughout Tennessee.
Preparing for Home Fruit Production
Overall Considerations for Home Fruit Plantings
While one gardener’s intention might be to provide a substantial amount of fruit for fresh eating or preserving, another’s might be simply to grow a few fruit-producing plants for their beauty, their grazing potential, or for sharing with wildlife. These different objectives require different levels of commitment, so the amount of time and effort the grower is willing to commit should be considered when making choices. Even for those willing to commit substantial efforts to fruit production, success will come more easily when the right decisions are made in the beginning. Choosing the right fruit — or even more specifically, the right kind of fruit and cultivars — for the purposes, the region, and the site is critically important.
The size of the property and of the plants is another consideration. While a small yard might be able to support several blueberries, caneberries, or grapes grown on vertical structures, the space can quickly be overwhelmed with tree fruits, especially if they are not dwarf forms. Research mature sizes and consider methods of training that may offer reductions in size before making realistic decisions.
While it might seem logical for gardeners to seek out the type of fruit they prefer when shopping at a grocery store, many of the types and cultivars represented there will not perform well in the Tennessee climate. Success depends heavily on planting regionally appropriate selections. Some will simply not survive, while others may live but not produce acceptable fruit. It cannot be stated too strongly that it is crucial to select appropriate sites as well as types and cultivars of fruit.
It also depends on the individual. Some gardeners prefer to grow fruit that requires little to no pest control, while others are willing to institute a regular spray schedule. Even those willing to undertake the more demanding control measures should still focus on disease resistance.
Cultivar selection for each crop is addressed in supplemental Extension materials.
Site Selection
Residential fruit growers generally do not have many choices in site selection, so it is important to make the best of the spaces available. With few exceptions, fruit crops need full sun throughout most of the day for health and productivity. Pawpaw trees are among the few fruit crops that will tolerate some shade, but even they will produce best with higher light levels.
Plants on a southern to southwestern slope can experience more cold injury because warming sun exposure can wake plants from dormancy earlier in the year when low temperatures are still likely to occur. On the positive side, these plants are often earlier to ripen. On northeastern slopes, plants will remain dormant later into the spring, reducing the chance of injury. An eastern exposure dries fruits and foliage earlier in the day to lessen the potential for disease.
Sites that are elevated around surrounding areas are desirable because they can be 5 to 10°F warmer for every 100-foot increase in elevation during radiation frost events. Since cold air is heavier and sinks, frost often settles in low areas, as illustrated in Figure 1. Elevated sites also experience less dew and settling of fog, reducing disease problems. Hilltops may not be as desirable because of the possible exposure to wind in some areas and the possibility that the rooting depth and water-holding capacity of the soil has been reduced by past erosion.
Well-drained soil with a pH of 6.0 to 6.5 is best for most fruit crops. Blueberries are an exception, preferring a soil pH between 4.8 and 5.2. A soil test is advised to see if lime is needed, which is often the case in many parts of Tennessee. Soils can be improved through top dressing with organic mulch or cover crops, though highly fertile soils may result in excess vigor in vegetative growth that can delay fruiting or reduce fruit quality. Some diseases and pests are also more problematic on lush new growth driven by excessive fertility. Adding appropriate fertilizers and nutrients to less fertile soils gives the gardener the ability to manipulate plant growth and fruiting.
Plant Selection, Purchase, and Care
Most fruit crops are available in containers or as bare-root plants. The term bare-root simply means that the plants were field-grown, dug, and shipped with a moist material wrapped around the roots to prevent drying. When properly managed, bare-root plants will perform as well or even better than those grown in containers. They are also often less costly. The drawback to bare-root plants is that they need to be shipped and planted while dormant.
Containerized plants have the advantage of a much wider planting window but have their own risks. Their roots could have been injured by cold, infrequent watering or excessively high temperatures. They can also develop dense or circling roots called pot bound, requiring corrective root pruning at planting.
Preparing the Planting Location and Plants
Planting about one month or longer before growth starts in spring allows the root system to become established and generally results in better plant growth the first year. Planting after the growing season has begun, especially if the weather is hot and dry, can result in poor growth the first year. Even with high-quality, dormant plants, fall planting may pose the risk of plant injury due to winter cold in some parts of the state.
Plants may be held in the shipping package for a few weeks if they are stored in a dark, cool, damp area, but they should not be exposed to subfreezing temperatures. Be sure to prevent the root systems from drying or freezing while stored.
If plants are to be held for a long time before planting, they should be “heeled in,” as shown in Figure 2. Remove plants from the packaged bundle, line them out in a soil trench, and cover the root systems with soil. Work the soil around the roots, eliminate air pockets, and water them in to establish good root-soil contact. Do not remove the plants from packaging or heeling in until immediately before planting. The root systems should never be allowed to dry out because even short exposure can cause damage. Immerse the roots in a bucket of water to transport them to the planting site.
Small Fruit Production
A wide variety of small fruits can be grown in the garden, but the most common are blueberries, strawberries, and caneberries. Success in growing blueberries is highly dependent on spending adequate time in preparing the site. Building raised beds, incorporating organic matter and adjusting the pH of the soil to proper levels are critical. Six to 12 months are often needed to prepare well. They can remain productive for many years and can also be added into residential landscapes to provide both aesthetics and food production. It will generally take six to eight years after planting to reach full yield potential. Time from planting to fruiting will vary because of differences in the age of the transplants, the rate of growth, plant health, and blueberry type.
Blackberries and raspberries, often collectively called caneberries, are also common in Tennessee home gardens. They are not easily harmed by spring frost, and they produce quality fruit consistently if well managed. A mixture of different types and cultivars of caneberries can yield fresh fruit for five to six months a year. Caneberries are known as vigorous plants, so they need to be grown in an area where they can be contained and maintained.
In addition to the longer-term blueberry and caneberry crops, strawberries are an herbaceous perennial that can be grown in a variety of systems and at a wide range of scales.
Blueberry Selection and Production
The three types of blueberries commonly grown in Tennessee are rabbiteye (Vaccinium virgatum syn. ashei), northern highbush (Vaccinium corymbosum L), and southern highbush, which are detailed in Universtiy of Tennessee Extension publication PB595A. Rabbiteye blueberries may bloom earlier and are native to the southeastern region. They are also more heat and drought tolerant with vigorous growth (12 or more feet) if left unpruned. Rabbiteyes usually require two or more cultivars for cross-pollination.
In Tennessee, northern highbush blueberries often perform best at higher elevations and generally require irrigation. Later flowering and earlier fruiting can help highbush cultivars better avoid spring frost flower injury and the effects of hot summer temperatures during harvest.
The gardener may find other blueberries called southern highbush, which are hybrids meant to have some of the preferable characteristics of highbush along with heat tolerance and a need for fewer chilling hours (typically between 150 and 800). However, lower chilling requirements can be a drawback as well, so only the southern highbush with higher chilling-hour needs are suitable for Tennessee (select those with 600-800 chill hours). Trials are still under way to determine the performance of these types for Tennessee growers.
Both types of highbush blueberries are more disease prone and sensitive to soil pH, organic matter, and moisture levels. So, they usually have a shorter lifespan than rabbiteye.
Northern highbush blueberries will tolerate lower winter temperatures and bloom a bit later in spring than rabbiteye. Many of the highbush blueberry cultivars are reported to have self-fertile blooms. However, all blueberry cultivars will produce more and larger fruit with cross pollination. A point of interest is that highbush blueberries do not grow “higher” than rabbiteyes; indeed, rabbiteyes can easily double their height. They are called highbush as compared to another species of blueberry called lowbush (Vaccinium angustifolium).
The earlier bloom of rabbiteye compared to highbush blueberries is the result of its lower chilling-hour requirements. The term chilling hours refers to the time in which a woody plant stays dormant to protect itself from low-temperature damage. After this specific cold period is completed, spring growth can take place. Plants with too few chilling hours for the location could bloom too early and be damaged by freezing temperatures, while those that need more chilling hours have their normal fruiting cycle disrupted as well.
A blueberry plant consists of many woody shoots growing from the crown. Blueberries often produce multiple flushes of vegetative growth during the season that can create a zigzag growth pattern on branches. Older woody shoots produce fewer fruits, so as new vigorous shoots emerge from the ground on mature plants the older ones can be removed, creating a plant that is self-rejuvenating and more productive.
Leaves of blueberries arise from slender vegetative buds. (see below.) Mature leaves have a waxy upper surface, which decreases the effectiveness of sprays after midsummer. Flower buds, larger and more spherical than vegetative buds, form during late summer to early fall, and each contains several individual flowers. Flowers begin to emerge when the chilling requirement has been reached and heat units begin to accumulate in the spring. Each individual flower’s petals are fused, forming a tube, which favors more effective pollination by bumblebees over honeybees, though honeybees do provide some pollination. Flower buds will be found on the terminal 2 to 3 inches of the shoots.
Site Selection and Blueberry Establishment
Site selection is vitally important. While proper pH helps all fruit crops, an acid soil is essential for blueberries. Growth is typically best in the 4.8 to 5.2 pH range, which may require initial and ongoing amendment with sulfur. Higher pH will cause iron deficiency of foliage, and plants will struggle to survive and flourish. While recommendations for reducing soil pH are available, a soil with a high native pH is difficult to change significantly for any length of time. Raised beds filled with suitable soil or growing media of an appropriate pH are advised in that situation.
Blueberry plants have a fine, thread-like root system that grows densely near the soil surface and mostly within the dripline of the bush. Blueberry roots also lack root hairs, which makes them less efficient in taking up water and likely more sensitive to low and high moisture levels in the soil. Highbush roots are mainly in the upper 8 inches, while rabbiteye types have the majority of their roots in the upper 12 inches.
In the South, productive highbush blueberry plantings are often best on sandy loam to loam soils that have a high organic matter content, whereas fine-textured, clayey soils are the least desirable. Shallow soils (less than 30 inches deep) or those with poor internal or surface drainage as well as high calcium content should be avoided. Raised berms or beds are a good option when drainage is a concern.
Rabbiteye blueberries can be productively grown on a wider range of well-drained soils that are not drought prone, including clay loams. On these sites with higher clay content, the pH is often kept at 4.5 to 5.2. Organic matter should be added if there is less than 3 percent on the site. Rabbiteye blueberries do not typically perform well on sites with very high calcium or phosphorus or those being rotated from other crops.
To summarize, blueberries typically grow best on soils having moisture (likely with irrigation), good drainage, and high organic matter. Slightly elevated sites allow air drainage that minimizes the risk of spring frost injury. Plantings that face north are also desirable because they warm up more slowly, making later blooms less likely to be damaged in a spring frost.
Healthy, true-to-name plants should be purchased from a reputable nursery. It is most common to purchase two-year-old bare-root or container-grown plants. When bare-root plants arrive, open the package and immediately check to see if the roots are moist. It is natural for blueberry roots to be brown on the outside and white on the inside. Until they can be planted, keep the plants in a cool, dark area with roots in moist packing or in dampened mulch or soil. Before or just after planting, remove approximately one-third of the top growth and all flower buds. Plants that are not allowed to flower and fruit in the first or second year after planting will put more energy into vegetative growth and establishment.
Rabbiteye blueberries are typically planted at an in-row spacing of 5 to 6 feet between plants, while highbush blueberries are typically planted with 4 feet between plants. Between-row spacing is generally 10 feet but can be adjusted for equipment needs.
Both rabbiteye and highbush blueberries benefit from cross-pollination, resulting in more fruit and larger berries. Since these two types are not likely to bloom at the same time, they will not be effective pollinators for each other. Instead, intersperse plantings of different cultivars within the same group. To extend the harvest season, plant a mix of early-, mid-, and late-ripening cultivars.
Amending soils for blueberries is possible, but incorporation of peat moss is not generally recommended because it can contribute to excessive moisture in the root zone during rainy seasons. Peat moss may be helpful if the soil is sandy and dries out quickly. It is generally easier to add water than to get rid of it, and most soils in Tennessee have enough clay to retain adequate moisture.
Manure, even well composted, is also not ideal because it can be alkaline and support rising pH levels. Composted pine bark can be added before planting to increase organic matter content if mixed well to eliminate the bucket effect. This condition occurs when a small area of amended soil around the newly planted root dries faster during drought and fills with water during wet times, creating poor conditions for consistent root growth. Roots also tend to grow within this looser soil rather than expanding to native soil. If soil drainage is a serious concern, consider raised beds of soil or a soilless substrate such as composted pine bark.
Do not put fertilizers in the planting holes because the salts they contain can draw moisture from the roots or cause salt burn.
Mulching with either pine bark or woven groundcovers is helpful to moderate soil moisture, but mulching may encourage voles, which can damage roots or lower stems. Providing adequate moisture without overwatering is very important as the plants become established. Watering needs vary by soil type, plant size, and weather conditions, so check moisture levels under the mulch. Drip irrigation is useful when there are many plants to be watered. Once the plants are established, supplying adequate moisture during dry times can increase fruit production and size as well as following crops.
Blueberry Soil Preparation
With the specific pH requirements of blueberries, a soil test is essential and should be taken several months before planting. Wettable sulfur (90%) should be applied several months before planting if the soil pH is below 5.3 (rabbiteye) or 5.0 (highbush). Follow soil test recommendations or use about 1 pound (2 cups) per pH unit (6.5 to 5.5 for example) that the pH needs to be reduced for every 100 square feet on sandy soils. Double this amount for heavier clay or loam soils or those with high organic matter. Aim for a pH of between 4.5 and 5.0 initially and add more sulfur later if needed rather than trying to achieve too much pH change over a short time period.
Blueberry Management
Blueberry plants do not prefer highly fertile soils, but on most soils production can be improved by modest annual nitrogen (N) applications. Moderation is the key, as excessive fertilization reduces vigor, production, and hardiness. Fertilizers containing ammonium nitrogen (NH4+) are generally best. Use phosphorus (P) and potassium (K) only if soil testing indicates a need. Monoammonium phosphate (MAP) and diammonium phosphate (DAP) are recommended if phosphorus is required. Remember that it is best to use fertilizers cautiously for the first year, as the fertilizer salts can pull moisture from the roots and hinder establishment. Start with small amounts of nitrogen in the second year and increase each year until a maximum of around 1.5 pounds of nitrogen per 1,000 square feet (around 3 pounds of urea or 7 pounds of ammonium sulfate) is applied on mature plants by their sixth or seventh year.
For the homeowner with just a few plants, the process can be simplified. Use a fertilizer formulated for acid-preferring plants such as azaleas, rhododendrons, or hollies (4-8-8 with micronutrients). Apply 2 ounces per foot of bush height up to 6 feet (1/2 ounce per foot if using ammonium sulfate 21-0-0; 1 oz per foot if using 12-4-8 or 10-10-10). Applications can be made at bud break and then twice more at 6 week intervals to assist in fruit-bud setting for the coming year. Spread the fertilizer on the soil evenly around the plants rather than in one heap to prevent salt burning. Do not fertilize after the first of August to allow new growth to harden off before the autumn frosts.
In the first and second year, remove fruit buds to stimulate growth of future fruiting stems. Once a plant has come into production, take note when the oldest canes become twiggy and less vigorous. Removing 1-3 of these older canes annually as close as possible to the soil will open the plant up and allow newer and more productive canes to flourish. Dormant pruning is the primary method of renewing fruiting wood on blueberries. In late winter, older and any damaged or low growing canes are removed. Older wood higher in the canopy can also be thinned to open up the plant center and increase berry size as fruit is produced on younger stems.
Blueberry flowers are pollinated when bees vibrate their wing muscles to shake loose the pollen, a performance known as sonication. The solitary southeastern blueberry bee and bumblebees (see page 12-10) are some of the best pollinators for blueberries. Honeybees are unable to pollinate in this way so they are less efficient, although they do provide some benefit.
Details on managing disease and insect pests of blueberry plants can be found in UT Extension Publication PB1622. Other problems can be voles that damage roots, especially when organic mulches are deep. Voles can also damage irrigation lines by chewing. Close mowing near the planting and cleaning up the surrounding area will aid in the control of these and other rodents. Birds are often the most frequent pest after the plants begin to fruit. The most effective way of discouraging them is by placing netting over the plants as soon as berries begin to turn color.
Be aware that while color change is the first indication of ripening, fruit will not reach full flavor and sweetness immediately after turning blue. A few more days on the plant will allow the fruit to swell and sweeten, often indicated by a slight lightening of the blue color as the berry’s skin develops a waxy, glaucous coating that will protect and preserve the fruit as it becomes more plump. Weekly picking is often sufficient, though some cultivars are more prone to cracking after rains. If spotted wing drosophila is present more frequent harvesting will be needed.
Caneberry Selection and Production
The term caneberries is used to refer to all plants in the genus Rubus, of which the most common are blackberries and raspberries. Caneberries have roots that are perennial but shoots that only live for two growing seasons, as shown in Figure 3. During the first year of growth, these shoots produce purely vegetative growth (stems and leaves) called primocanes. In the second season of growth, however, they produce flowers and fruit and are called floricanes. They die at the end of the second season and should be removed. However, there are now many cultivars that produce fruit on primocanes; they are called fall or everbearing varieties. Find additional type and cultivar information in University of Tennessee Extension publication W895B.
Blackberries are well adapted for home gardens across the varied climates of Tennessee. They thrive on well-drained soil in full sun. While easily grown, blackberries often need a trellising system and regular pruning because of their natural vigor and sprawl. Many newer blackberry cultivars have an erect or semierect growth habit that can simplify some management, but all types will benefit from trellising. Tip pruning during the summer will control growth and increase the fruit crop for the next year. (see additional Extension resources for details on pruning and training.)
Breeding advances, many from the University of Arkansas, have provided many new cultivars with improved flavor, yield potential, and disease resistance. Features such as thornless canes and the ability to fruit on primocanes are also available in cultivars now on the market for home gardeners. One of the potential drawbacks of blackberries is that they tend to be less winter hardy than raspberries.
Raspberries, the second common caneberry crop for gardeners, are available as red, black, yellow, and purple types. The word “type” is used intentionally, because they differ in color of fruit, growth habit, and disease issues. The two main types of red raspberries are floricane (summer-bearing) and primocane-bearing. Summer-bearing red raspberries bear fruit in the early summer and have the typical biennial lifecycle, with floricanes dying after fruiting. Primocane-bearing types form fruit on the upper portions of the canes during the first year in the fall. These raspberries, also called everbearing, fruit again the following spring on buds closer to the base of the plant.
Red raspberries, both floricane and primocane fruiting, generally produce new canes (suckers) from the root system, so they are usually grown in a hedgerow. Red raspberries are the most winter-hardy bramble and can survive temperatures as low as -20°F when properly acclimated. Once a plant begins to lose its dormancy, it can be injured by temperatures it could survive well while dormant.
Raspberries have less winterkill than blackberries, but they are more susceptible to anthracnose and viruses and are less tolerant of summer heat. This difference could be a major factor in determining whether to plant blackberries or raspberries, keeping in mind that the higher elevation or cooler parts of the state are better suited to raspberries. Gardeners in warmer areas of Tennessee will find that raspberry success depends on careful selection of heat tolerant cultivars. Red raspberries are also likely to require support to improve cane erectness and keep fruit from resting on the soil.
Black raspberries initiate new canes from the crown of the plant instead of from root suckers, and they are usually grown in a hill system. Unlike the hedgerows typical of red raspberries, each black raspberry plant is grown, pruned, and maintained as an individual. Black raspberries are usually tip pruned in the summer because single canes will grow quite long and be difficult to manage. While they have the earliest fruit, black raspberries are also the least winter hardy of the raspberries.
Purple raspberries are hybrids of red and black raspberries. They usually grow new canes from the crown, but they can produce root suckers between plants, showing characteristics of both black and red. Purple raspberries are grown similar to black raspberries and are intermediate in cold hardiness between red and black. Gold raspberries are mutations of red that are also available, although not as widely grown.
Site Selection and Caneberry Establishment
Caneberries require full sun and well-drained soils, and they grow best in soils that have a pH of 6.0 to around 6.5. It is best to take a soil sample and determine needs for pH and fertility management the year before planting. Low-pH soils should be amended with lime the fall before planting.
Plantings made on a slope (preferably north and east) are in less danger of blooms being killed by late frosts than plants in low areas. It is best to amend the soil with additions of organic matter before planting. Perennial weeds should also be controlled before planting. Sites where strawberries, potatoes, tomatoes, peppers, or eggplants have been recently grown should not be used because of the risk of transmitting Verticillium wilt.
Buy virus-tested caneberry plants, and plant them in the early spring. In-row spacing varies based on plant habit and support systems, but is typically 24 to 36 inches for primocane-fruiting raspberries and 36 to 48 inches for floricane-fruiting raspberries. Erect growing blackberries are spaced 24 to 48 inches while those with a more trailing habit are spaced 48 to 96 inches apart. Between-row spacing should be at least 6 feet, but it can be up to 10 to 12 feet to enable easier mowing of aisles. Dig holes large enough to spread the roots and cover them with 2 to 3 inches of soil. Water well immediately after planting.
Caneberry Management
Caneberries benefit greatly from irrigation, especially during fruit swell, which occurs the week before the fruit ripens. Trickle or drip irrigation is best because wetting the fruit with overhead irrigation may increase the incidence of disease. Irrigation will also greatly enhance the emergence and growth of primocanes during dry periods. Irrigation should be closely monitored because caneberries do not tolerate wet soils, which can lead to root diseases and loss.
In the first year of growth, follow the soil test recommendations for meeting the plants’ phosphorus and potassium needs. Apply 1 to 2 ounces of actual nitrogen per 100 square feet divided into three monthly applications of 1 to 2 ounces of ammonium nitrate; 34-0-0 monthly from May through July. In subsequent years, apply 2 to 3 ounces of actual nitrogen per 100 square feet in two 3 to 5 ounce applications of ammonium nitrate both spring (when primocanes emerge) as well as after harvest. These fertilizer estimates should be reduced or fertilization should be omitted on very fertile soils.
Keep in mind that summer-bearing red raspberries produce suckers from the roots, so they will spread. They are grown in a hedgerow where suckers fill any open spots in the length of the row and will need to be managed closely to be kept within that hedgerow. Blackberry and black raspberry plants need to be managed individually, as new canes grow from the crowns.
Caneberries should be harvested in cooler parts of the day. Wait until dew is gone to reduce the spread of disease, and do not harvest during the hotter parts of the day when field heat builds up in the fruit. Ripe raspberries separate easily from the receptacle (core), while cores are picked with blackberries. Pick them into shallow containers to prevent upper layers of the fruit from crushing those below.
Picked berries need to be kept out of direct sunlight and moved into cold storage immediately at temperatures no higher than 35°F, which will allow them to keep up to a week. However, raspberries do not have good shelf life, partly because of the fruit’s structure, which consists of loosely attached drupelets, and partly because of high postharvest respiration rates and susceptibility to Botrytis fungus. The shelf life of blackberries is often longer than that of raspberries.
Strawberry Selection and Production
Strawberries are unique herbaceous perennials composed of leaves, crowns, and roots. The root system consists of semipermanent roots that last for multiple seasons plus some shorter-term roots. Runners, or modified stems called stolons, arise from the buds at the base of the leaves. These stolons enable asexual reproduction as they root into the soil and produce new plants.
The most commonly grown strawberries are the June-bearing type, but it is common to harvest earlier in Tennessee. June-bearing strawberries are short-day plants that initiate flower buds. This day length begins in the short days of late September through early November. A good canopy of leaves is needed to provide energy for flower bud initiation, so be sure to control weeds. Temperatures below 60°F will also induce flower bud formation. Ever-bearing and day-neutral strawberries (which are different biologically but similar in use) are less commonly grown but do offer some benefits such as a wider harvest season and suitability for growing in containers or small areas. Find more information about cultivars in University of Tennessee Extension publication W895C.
Site Selection and Strawberry Establishment
Strawberries require full sun, and they benefit from slight slopes to drain cool air away in the spring season. Strawberries should not be planted where potatoes, tomatoes, eggplant, peppers, or raspberries were grown in the past three years because of the risk of the soil-borne fungal disease Verticillium. Several strawberry cultivars have some resistance to this pathogen. In addition, strawberries should not be planted in areas where sod has previously grown because grubs that feed on grass roots will also feed on strawberries. Sites that are heavily infested with sedge, nutgrass, quackgrass, Johnsongrass, or thistles should be avoided or treated with an herbicide before strawberries are planted.
Strawberries grow and produce satisfactorily in a wide range of soil types from sandy to heavy loams. They are not notably sensitive to soil pH, but they grow and produce best in soils with a pH of 6.3 to 6.8. Deep, fertile soils with high organic matter and good internal drainage are best. A shallow root system is partially responsible for the strawberry plant’s sensitivity to water deficiency and excess, so poor drainage can result in poor vigor caused by reduced oxygen in the root zone. Wet soils also encourage fungal diseases.
As with other crops, the site should be selected the year before planting so that soil tests can be taken and pH adjusted as recommended with lime or sulfur and fertilizer.
The most common method of growing for home strawberries in Tennessee is the matted row system. This growing system essentially enables new plants from runners to establish, grow and replace older plants in the same bed over time. If the plants remain healthy, matted row beds can last for many years. In matted row production, the site is planted with virus-free, one-year-old plants often set out about three or four weeks before the date of the last spring frost in the matted row system.
Plants are generally set out 18 to 24 inches apart and it is common for them to be planted in a grid pattern in rectangular beds rather than in distinct, single rows. Plant strawberries so the soil level is at the bottom of the bud. Roots should be spread out and the soil gently tamped down around them to prevent air pockets that would allow roots to dry out or be unable to take up water. See Figure 4 for proper planting depth.
In the first summer, flowers will be removed, but runners will be allowed to establish new daughter plants. The first harvest of matted row strawberries will then be a little more than a year after planting.
Strawberry Management
The ideal time to apply fertilizer to strawberry plantings is after harvest and in late August or early September. Nitrogen should not be applied to established plantings just before or during fruit harvest. Doing so can cause the fruit to be soft and more susceptible to disease. It is common to apply only nitrogen after preplant fertilization used to address any phosphorus or potassium needs. A typical fertilization schedule would be to broadcast 1.5 lb 10-10-10 (if P and K are needed) or 0.5 lb ammonium nitrate over per 100 square foot after harvest and then again in late August. Apply when foliage is dry and brush off the leaves to remove fertilizer and prevent it from burning the leaves.
Strawberries and other small fruits benefit from being mulched with organic materials. A 2- to 4-inch pine needle or wheat straw mulch is ideal. Mulches should be applied in early winter after the plants have been exposed to several freezes and are fully dormant. This timing will protect plants from winter injury and will delay flowering in the spring, providing frost protection to the blossoms. When growth begins in early spring, most of the mulch should be removed to allow sunlight to reach the plants. Mulch pulled off the plants can be placed in walkways to help suppress weed growth and keep fruit on the row edges off the soil. Leaves should not be used for mulch because they can smother plants. Mulches may provide shelter for rodents, but the benefits of mulching generally outweigh potential problems.
Irrigation is required for a good crop of strawberries because the root system is shallow, and rainfall in Tennessee is often uneven. Drip irrigation has been used successfully to provide adequate soil moisture for strawberries to ensure plant health and efficient use of water.
Birds are one of the most prominent pests attacking strawberries in home gardens, so netting may be needed.
In the matted row system, renovation is the process of removing the parent plants and renewing the strawberry bed with the daughter plants to support production and health. It usually occurs shortly after harvest and can be combined with fertilization and weeding. Renovation is best done annually. First, recommended fertilizer is broadcast applied and brushed in. Then, cultivation (usually roto-tilling) is done in strips to narrow rows or create new walkways in the beds. Typically new walkways 18 to 24″ would be tilled to create new 12 to 18 inch rows of mostly young plants. This cultivation will also remove many weeds and incorporate fertilizer. Water well after renovation.
The other common method of production is called the plasticulture or annual system. Plants are generally planted in the early fall to establish and set buds before winter. They are often covered to protect them during the winter. They then flower and produce fruit, which are harvested the following spring, after which the plants are removed. The plasticulture system is essentially an annual growing system that maximizes productivity and minimizes maintenance. While it is most commonly practiced in commercial strawberry production, homeowners who would like to reduce the maintenance associated with perennial strawberries may be interested.
In the home garden, strawberries should be allowed to become fully ripe before harvesting because sugar content is highest and flavor is best at that time. To prevent bruising, berries should be picked carefully by the stems. Berries will not keep long on the plant, so daily harvest will likely be needed during the most productive times in the season. Strawberries can be stored in the refrigerator for a few days.
Types of Strawberries
June-bearing strawberries produce a single large crop during a two- to three-week period. They produce a single flush of runners and flowers and may be classified as early, mid-, and late-ripening varieties.
June bearing strawberries are commonly grown in home gardens in matted row production, and common cultivars include Earliglow, Allstar, Cardinal, and Flavorfest. Chandler and Sweet Charlie are June-bearing cultivars more commonly used in annual or plasticulture production.
Day-neutral and everbearing strawberries produce fruit at multiple points in the growing season. They produce fewer runners, which makes them optimal for small gardens or areas with limited space. In terms of physiology, these plants can be day neutral or long-day, which means flowering is initiated when daylength increases to a certain level. Examples include Albion, Seascape, Tribute, andTristar.
Grapevines and Tree Fruits
Table and Wine Grape Selection and Production
Grapes are used for making wine, for drying to produce raisins, and for eating fresh. Their cultivation goes back to ancient times. For the home gardener, production of table grapes is the usual objective. Although grapes are adapted to a wide range of soils, including dry and rocky, that does not mean they are always simple to grow in Tennessee. Grapes are subject to many insects and diseases, and some types of wine grapes are limited in Tennessee by disease and climate risks. See University of Tennessee Extension publication W895E for cultivar selection details.
Other factors that should be considered before deciding to plant grapes for fresh consumption include structural needs. Grapevines require sturdy and durable support systems, so time, effort, and expense are required to build trellising structures. Timely pruning is another rigorous task that requires considerable time and attention to detail.
Following a preventive spray schedule for pests should be considered a necessary task for producing harvestable fruit. Combined with good siting and IPM practices, a spray schedule might be minimal but is still recommended, especially for black rot, which can destroy fruit as it ripens. In short, grapes do require considerable effort when grown in Tennessee gardens.
Three species and their hybrids are important in grape breeding. American bunch grapes are Vitis labrusca. Vitis vinifera is the European bunch grape important in wine making. V. vinifera is not well suited for home gardens in our region. However, there are many European-American hybrids that can be grown for wine production in Tennessee.
The third species of grapes (Vitis rotundifolia), called muscadines, is an option for gardeners in warmer parts of Tennessee because they have fewer disease issues. Muscadines are native to the southeast, and breeding has resulted in several large and flavorful cultivars that can often be grown in a low-spray system. They still require trellising and an intensive pruning regime, so they are not necessarily a low-maintenance crop. Muscadines have a distinct musky flavor. They contain seeds and have a tough skin that is usually not swallowed when eating the fruit fresh. However, breeding efforts have resulted in seedless cultivars including some with thin, edible skin that are currently being tested.
One of the drawbacks of muscadines is that they can be killed by severe winters. Muscadines are questionable for zone 6, though it may be possible to find a microclimate on your property that offers a few degrees of protection. Breeding efforts are under way to develop greater cold hardiness and there are now several cultivars with perfect flowers (having both male and female parts) and that do not require additional plants for pollinizers.
When selecting grape types and cultivars, do not settle for what is locally available if it is not well adapted to your region or resistant to common pests. Grapes found at the grocery stores such as ‘Thomson’s Seedless’ are not going to be adapted to the Tennessee climate and soils. Research those grapes that have been shown to be better adapted to the Southeastern climate and resistant to the most common pests and disease. Flavor and productivity are certainly factors, but growers may also wish to plant early, mid-, and late-season vines as season extenders. Some cultivars are better adapted for juice or jellies than fresh eating. Though these table grapes are not typically grown for juice or wine, many enjoy experimenting with them for those purposes.
Site Selection and Grapevine Establishment
Grapes require full sun, at least 8 hours per day, and well-drained soil, ideally with a pH of 5.5 to 6.5. High fertility soils are not necessary or even desirable, as lush growth may contribute to disease pressures and create more shade than is optimum. Sites with good air circulation will help to suppress fungal diseases.
Consider spacing needs when selecting sites, as the vines should be planted 6 to 10 feet apart for table grapes, though muscadines are more vigorous and spaced more widely (16-20 feet). If more than one row is to be planted, let the spacing between rows be determined by the width of your equipment plus 4 feet. Spacings of 10 to 12 feet are usually suggested. Rows that run north to south will provide more equal sun on each side, but this orientation is not essential. Also be aware that spring planting of muscadines is best so that the vines have time to become well established before the onset of winter weather.
Table grapes are self-fruitful, so it is not necessary to order more than one vine for pollination, but planting more than one type can lengthen the harvest season and offer different flavor profiles. Some muscadine cultivars have only pistillate flowers and thus require perfect-flowered cultivars to be planted nearby as pollen sources.
Reputable nurseries will supply that information in the cultivar descriptions. Seedless grapes are tempting, but selection for resistance to disease is the more important criterion. Table and muscadine vines are typically grown on their own roots (not grafted), and only some wine grapes will need to be grafted. In these grapes, grafting can provide resistance to Phylloxera (a tiny, aphidlike insect that damages roots) or nematodes. Some lower vigor cultivars can also be improved by grafting. Grape cultivar selection publications will provide more detailed information on these topics.
Plants may be offered in containers, but often a wider selection of locally appropriate or disease resistant cultivars are ordered and shipped as bare-root plants available during the dormant season. Soak the roots in water for a few hours before planting. Plant at the original soil depth and water to settle the soil around the roots. Do not add soil amendments to the hole, as they can create a “flower pot” effect, preventing or slowing roots from expanding into the native soil. Do not add fertilizer to the planting holes. Assuming soils have been amended before planting, nitrogen (N) is the only nutrient needed after planting.
At planting time, pruning is recommended to set the stage for developing a plant of the desired shape and size, with the goals being to maximize production and quality. While there are many ways to prune, the principles remain the same. Various styles will be covered later, but at planting the only pruning needed is to cut the plant back to one shoot having two or three strong buds, one of which will be developed to become the main “trunk.” The second or third bud is left simply as “insurance” should the first bud not make it. The main trunk should be trained as straight as possible up to the trellis wire.
It is best to keep the strip under the vines weed free to a distance of 2 to 3 feet on each side of the row to avoid competition for water and nutrients. Drip irrigation is ideal to aid in establishment. Applying an inch or so each week is desirable, though newly established vines may require more. Overwatering can kill plants as well, so be sure to monitor plants for their needs rather than relying only on regularly scheduled watering.
Grapevine Management
Fertilization and Watering
Grapevines are not heavy feeders. In fact, too much fertility will result in lush growth and reduced fruit production. Once plants are established, it is common for nitrogen to be the only nutrient required, so do not use complete fertilizers if soil tests indicate phosphorus (P) and potassium (K) are adequate. One to 2 ounces of a nitrogen fertilizer such as calcium nitrate or ammonium sulfate is adequate for each plant the first year, applied by scattering it in a 2-foot circle, not piling it near the trunk. One to 2 ounces of those nitrogen fertilizers should be added the second year both at bloom and again in mid-July in a 3-foot-diameter area around the trunk. For vines three years and older, 0.2 pound (3.0 ounces) of actual nitrogen per vine is typically recommended. This would be 1 pound per plant of ammonium sulfate or 2 pounds per plant of 10-10-10 fertilizer (if phosphorus and potassium are needed), which should be spread evenly in a 4-foot-wide band at around the time of bloom. Sandy soil may require additional nitrogen.
While grapes can be drought tolerant, they certainly benefit from a proper regime of supplemental water. Fruit production and size will be improved, as will quality, because fruit splitting can occur if there are rains just as fruit ripens after a dry spell. Regular water can minimize that impact.
Weed control is important in vineyards because weeds may harbor pests or disease, and grapes do not compete well with weeds. A permanent sod is generally established to prevent erosion between rows. The use of hand weeding or herbicides is then used to maintain a weed free area around the vines. Mulching is actually not recommended for grapes because of the increased risk of root borer, which are a type of moth whose larvae can severely damage grapes by tunneling and feeding in roots and crowns.
Training and Pruning
While a trellis does not need to be constructed prior to planting, it should be in place by the first dormant pruning. If a trellis is not in place at planting, stake each plant to facilitate establishing an upright trunk. While there are many trellis styles, the principles are to ensure that the vines are strongly supported and the foliage is provided maximum air movement and sunlight. Providing access to the vines for pruning, pest management, and picking are additional benefits. Trellis systems should be sufficiently sturdy and made of rot-resistant wood or steel. (see page 12-19). Skimping on the front end may result in troublesome collapse as vines reach full productivity. It is better to prevent than to repair!
For the purposes of explaining training methods, it will be assumed that the grapes are planted in a row, using a two-wire vertical trellis. Vines should be at least 8 feet apart in the row and each should have its own support post or stake for training the trunk. Though large support posts may not be needed for each vine, there must be a substantial load-bearing post every few vines for good support, and good anchoring at each end of the row. Stringing smooth galvanized No. 10 or No. 12 wire horizontally between the posts is recommended, and a good training system might have one wire at 42 inches and a second one at 72 inches above the soil. This would allow enough room below the lower wire to suspend an irrigation tube if so desired and support air circulation.
Grapes can still be productive when grown as an espalier against a wall or fence, trained over an arbor, or even trained as a tree-like plant, called a “head-trained vine,” as long as they have adequate sunlight and other beneficial cultural practices are followed. While methods of planting and trellising are similar for the various types of grapes, the disease resistance of muscadines might make them a simpler choice for the edible landscape. They can be trained over a sturdy arbor or gazebo if pruning access is provided. Their drought, heat, and pest resistance also make them more adaptable to less-than-ideal sites, so they can be considered a lower maintenance fruit, except for the recommended pruning.
There are two main pruning methods (cane renewal and spur pruning), but the central objective is the same for both: to leave one-year-old wood to produce fruit. This goal can be met (1) by removing the canes entirely after their fruiting season and tying the new canes from the previous year’s growth to the wire, or (2) by leaving that lateral cane as a “limb” that will be allowed to produce fruiting “spurs” that are cut back to allow only two to three fruiting buds. These spurs should be spaced about 4 – 6 inches apart.
Once a grapevine gets out of hand, it can be challenging to return to good production, so do not skip a year. However, if renewal pruning is needed after vines have been neglected, vines can recover and there are many ways to reestablish good maintenance practices.
Grapes can be hosts to several fungal diseases of foliage, stems, or roots. Some will be problematic and will require a vigilant preventive regime of timely sprays that may begin at bud break or earlier and continue past harvest. Minimizing the impact of disease starts with an integrated management approach that should include appropriate site selection, good cultural practices, careful variety selection, canopy management, and orchard sanitation.
The site should be sunny and well-drained, and it should have exposure to good air movement. Prune to open the canopy to light and air. While most heavy pruning is done in winter, limited summer pruning is acceptable to open the canopy to air movement.
Sanitation is a hugely important task and is often neglected. Disease inoculum (material that spreads disease) overwinter in dropped leaves and fruit, so raking and removal of any plant debris is key. Sanitation procedures should also include removal of any diseased wood or mummified berries in the canopy. Liquid lime sulfur applied to the bark and wood of the vine near the end of winter can also help reduce inoculum that may be overwintering there.
Harvesting
Color may not be the best indicator of harvest readiness in grapes. Some cultivars are ripe when green, and other factors such as shading can affect color development. Some grapes may have developed external color before they are fully ripe. Look at seeds to see if they have changed from green to brown and taste the grapes for sweetness and texture. Stem color can also indicate ripeness as it begins to brown.
Unlike most other fruits, grapes will not ripen after harvest. Grapes used to make jelly should be harvested a little early to get a light, clear jelly. Grapes for fresh consumption should be harvested at highest taste and table quality. Grapes harvested for juice should generally be allowed to ripen fully for maximum sugar levels. Grapes used in wine production should be harvested when the pH, total acidity, and sugar level of the juice is at the optimum level for wine production.
Tree Fruit Selection and Production
Fruit trees will generally require more time and effort to keep well-maintained and productive than small fruit or ornamental trees. Full sun and deep, well-drained soil are essential for good productivity. Additionally, the site will need to accommodate the mature size of the tree.
While space is certainly a consideration for growing tree fruits, having a small yard does not necessarily rule it out, as there are some training methods that can minimize space needs. Espalier pruning trains a plant to grow flat against a wall or other support such as a wire trellis, as seen above. Fruit trees can also be selected that grow in tight columnar form. Many tree fruits can be successfully grown in Tennessee if proper care is taken in crop and cultivar selection. Apples (Malus domestica), European pears (Pyrus communis), Asian pear (Pyrus pyrifolia), and peaches (Prunus persica) are some of the most common. Apples and potentially pears are likely to be more productive over time while peaches can be more challenging. See University of Tennessee Extension publications W895 D and W895 F for additional information on tree fruit cultivar selection.
Many diseases and pests can damage and reduce fruit harvests, so selecting cultivars with resistance to the most common diseases is important (see additional Extension materials for cultivar selection). Resistance is often used in conjunction with carefully managed spray programs to prevent (or lower) the impact of many of these diseases. Proper pruning and training are also crucial for fruit tree health and productivity. So, disease tolerant cultivars are a key asset, but don’t assume that resistance will enable fruit trees to perform well with little to no management. Cultural management including cultivar selection, site selection, pruning, training, pest and disease control, and sanitation are essential.
In selecting fruit crops and cultivars, it is also important to be familiar with grafted trees. Grafting is attaching a shoot piece from a tree with the desired fruit (scion) to another tree’s root system (rootstock). Once the vascular systems grow together, the resulting tree has the desirable shoot attributes of the scion and root attributes of the rootstock. Desirable rootstocks may be resistant to soil diseases or pests or control growth (dwarf or semi-dwarf). Many rootstocks are vegetatively propagated (also called clonal), but trees grown from seed (called seedlings) can also sometimes be used as rootstocks. Rootstocks used to control tree size and the lower vigor of a rootstock can reduce mature tree size. Earlier bearing of fruit is also common with rootstocks (called precocity).
While it may be fun to experiment with seed-grown tree fruits, if the objective is to get reliably tasty fruit in a relatively short time, it is best to rely on named and vegetatively reproduced plants. For example, if a number of persimmon seeds are planted, it will not be known for many years whether any of them are fruit-producing female plants. And, more importantly than timing, disease resistance and desired dwarfing characteristics are key assets of grafted plants with carefully selected scions and rootstocks.
Being a Savvy Fruit Tree Buyer
When should planting be done for bare-root and container plants?
Perhaps the best time to plant bare-root fruit trees and grapevines in Tennessee is in late winter to early spring (mid-February through mid-March). Container-grown trees and vines may be planted throughout the year. However, supplemental watering for all container-grown plants and staking of trees will aid in the survival and growth of these plants.
What should you look for when bare-root plants arrive?
When trees or vines arrive from the nursery, inspect them to see that the roots are moist and in good shape. A healthy root should feel firm when squeezed — not spongy, but also not brittle. The interior tissue of a healthy root should be white to a very light tan color. Darker colored root tissue suggests problems. If the roots are dry or discolored, contact the nursery. If the plant feels brittle, dry, and not pliable, make a small nick in the stem to see if there is living green cambium tissue just under the bark.
Tree Fruit Planting and Establishment
Many consumers assume that bigger is better when selecting fruit trees, but the reverse may actually be true. Healthy, small- to medium-size trees may have better survival rates, develop a more desirable shape, and begin to bear before larger plants. Larger trees are more likely to have branches growing at the wrong height, have branches poorly distributed around the trunk, have weak crotch angles, or have been damaged during digging, packing, or shipping. For these trees, having limbs at desired heights and locations will be difficult. Since proper early pruning is essential for later tree structure and fruit production, beginning with a smaller tree can enable proper training to be begun immediately rather than needing to begin with corrective steps. For best results, follow these suggestions:
- Select apple and pear trees that are 4 to 6 feet high (3/8- to 5/8-inch in diameter) with no side branches.
- Select stone fruit trees about 24 to 30 inches in height, or the next larger or next smaller size if unavailable.
Note that stone fruits typically side branch in the nursery, so those branches should be removed at planting.
Always purchase trees from a reputable nursery to ensure acquiring healthy plants of the correct variety. As long as the variety and the rootstock are adapted to Tennessee growing conditions, it is not essential to purchase plants from local nurseries. In fact, it may be necessary to purchase plants from more distant nurseries to obtain the desired varieties.
Dig holes just before planting; otherwise rainfall can seal the sides of the hole and slow root growth after planting. If soils are wet when the holes are dug with spade or auger, the sides and the bottom of the hole could be made very smooth (glazed). Before planting, always roughen the edges of the hole with a shovel to create an easier path for roots to grow into the soil. Holes should be dug wide enough to fit the root system without crowding or bending the roots. Roots that are curled to fit the hole will not straighten out to grow into the surrounding soil.
For seedlings (nongrafted trees), try to plant at the same soil depth as they were in the nursery or even a bit higher in case they settle. Look closely at the color and texture of the bark on the trunk to find the original soil line. For grafted trees, the graft union should be above ground. If the grafted tree is planted too deep, the scion (the variety grafted onto the rootstock) will root and the rootstock characteristics will be lost. Trees set too deeply may die or grow poorly. Trees planted too shallow can be poorly anchored, show weak growth, or exhibit increased suckering (shoot growth from the rootstock).
Straighten and spread out the roots as the tree is placed into the hole. If the roots will not fit into the hole, prune the long roots rather than bending them. All dead, broken, or diseased roots and any with pest issues should be removed. Once the roots are spread, backfill the hole with the same soil, and water it if needed.
Do NOT mix amendments such as peat moss, sawdust, manure, or fertilizer with the soil when backfilling. These materials can discourage roots from growing into native soil. This restricted growth can lead to a root-bound plant that is stunted or weakened. When filling the hole, work the soil among the roots to reduce the number and size of air pockets. Watering in after planting can also help settle the soil around the roots to provide good soil-to-root contact. If a depression has been formed as a place to water the plant during the first summer, fill it in before winter because it can collect water around the trunk in cold weather, leading to damage when water in contact with the tree trunk freezes and thaws.
Tree Fruit Management
Weed Control
Weeds compete heavily with young trees and vines for water and nutrients. This competition can reduce growth and even threaten survival during hot, dry summers. Therefore, it is best to maintain weed- and grass-free areas at least 2 to 3 feet from the trunks of trees.
Weed and grass control around young plants is accomplished primarily by hand. Lawn mowers and string trimmers can seriously injure or kill trees and vines. Shallow hoeing can also be effective, but it should be done carefully so as not to injure the trunks or shallow young roots. Herbicides can be an option for weed control but must be selected and used very carefully to be effective and not cause any damage to trees.
One useful and safe option for weed control and soil moisture conservation is mulch. However, do not place it directly against the trunks of trees because it provides sites for insects, diseases, and voles to damage the plant. Keep mulches or pea gravel back from the trunk about a foot to allow sunlight and air movement on all parts of the trunk.
Soil and Fertility Management
If a soil test indicates a need for nutrients, preplant apply the recommended fertilizer broadcast over the planting area. Don’t place fertilizer where it can be washed against the young tree because the fertilizer can burn the bark. In the years after planting, take yearly soil samples under the canopy. Separate samples should be collected from different types (not varieties) of crops because specific nutrient uses may vary.
If the soil pH gets significantly lower than the ideal range, some nutrients may be unavailable and others too available. If the addition of lime is recommended, it should be broadcast uniformly over the entire orchard or vineyard floor, not just around the plants.
For established plants, the best time to fertilize is about one month after new growth appears in spring by broadcasting uniformly on the ground under the canopy. To support the growth of young, nonbearing trees, a couple of light applications of fertilizer can be made monthly until midsummer. However, lush, succulent growth is not desired and can increase disease risk. One of the diseases that can be more damaging in trees with over-fertilized or lush growth is Fire blight. Apples and especially pears are susceptible to this bacterial disease and proper cultivar selection as well as cultural management will be needed for control. To prevent plants from growing too late in the fall and sustaining cold damage, fertilization should not be applied past midsummer.
Sometimes early spring weather will impact fertilization practices in fruit trees. One example involves stone fruits, where late frosts or freezes can reduce or eliminate crops. For such trees, the fertilizer application could be split by applying half of the desired amount a month after bud break in spring. After the chances of spring frosts have passed — and if a good crop remains on the tree — the other half of the fertilizer can be applied. However, if frosts have thinned the crop or eliminated it, the second application can be eliminated or reduced.
Nitrogen fertilization rates are based on the type and characteristics of the plant; its age, size, and growth; and its fruiting during the previous year. The intent is to maintain moderate, desirable growth while preventing excessive growth that could damage yields or increase disease susceptibility. Nitrogen rates for fruit trees (except pears), are calculated at the rate of 0.1 pound of actual nitrogen per year of tree age, with rates leveling off at about the sixth or seventh year. For example, a three-year-old peach tree should receive 0.3 pound of actual nitrogen, which could be supplied by 1 pound of ammonium nitrate (34 percent nitrogen). Pears should be fertilized at half of this rate because of their susceptibility to fire blight (a bacterial disease), which is worse when trees are growing vigorously.
Harvesting and Storing Tree Fruit
Fruits that will be stored awhile should be harvested at an earlier stage of ripeness than those for immediate use. Fully tree-ripened fruits generally have the best eating quality, but they do not last as long in storage.
European pear varieties such as Bosc, Seckel, Moonglow, Ayers, and Keiffer have fewer grit cells and attain better quality if they are picked at a mature green stage, held in a refrigerator for a couple weeks, and then allowed to ripen fully at room temperature. For highest quality, Asian pears should be harvested from the tree when ripe.
Many consumers and gardeners assume that surface color determines ripeness. Color can be misleading because many fruits develop red color well in advance of ripening. In many cases, the under color (or ground color) is a more reliable indicator of ripeness. When ripe, the ground color turns from green to yellow in yellow-flesh peaches. In white-flesh peaches, the ground color turns from green to a greenish-white or white. On many apple varieties, the ground color turns first to a pale green and then to a greenish-yellow as the fruit becomes riper.
Fruit drop can be another indicator of ripeness. When sound, high-quality fruit begin to drop from the tree, it generally indicates ripeness. Also be aware that fruits suffering disease, insect, or mechanical damage may ripen or drop early.
Most fruits to be stored are harvested before they are fully ripe to increase storage life and quality. Never store diseased or damaged fruit because they will deteriorate quickly. Apples stored with potatoes, onions, cabbage, and peppers for extended periods can also pick up flavors. Storage life varies by cultivar, so many home orchards are composed of a mix of cultivars for fresh eating as well as those with longer storage life.
Fruit crops should be stored at temperatures around freezing (30 to 35°F). The relative humidity of the storage location should be between 85 and 90 percent to reduce moisture loss and shriveling. Also, good air circulation prevents the buildup of gases produced by ripening fruit. Most refrigerators have higher air temperatures and lower moisture levels than is optimum for fruit, so use plastic bags to prevent moisture loss.
A Few Words on Fruit Morphology
My, what a sweet and juicy mesocarp!
That’s the part one eats when devouring a peach, plum, or cherry: the flesh surrounding a single, hard seed. This type of fruit is called a drupe, and trees producing this kind of fruit are often lumped together and called stone fruits.
And those hard seeds in blackberries and raspberries? They qualify as drupes but are called drupelets because many are fused together to form an aggregate fruit. They develop from a single flower with many ovaries, whereas a multiple fruit is the product of many separate flowers that fuse closely as they develop to form the edible mass, such as pineapple and mulberry. The fig is an unusual fruit called a syconium, essentially a flower receptacle (base) that contains numerous interior flowers, consumed as the fruit. Actually, the flower structure is what one eats.
Apples develop from a single flower, and their edible tissue is called a fleshy receptacle (hypanthium). It is the fused base of the petals and sepals with the wall of the ovary. Essentially, the bottom of the flower, where petals are attached, begins to grow and envelop the fertilized ovary (core), eventually covering it in juicy, tasty tissue. This covering tempts animals to eat it and spread the seeds contained in the center. Apples, pears, and quince all have this structure and are called pome fruits. Pomme is the French word for apple.
A persimmon is a true berry, with seeds scattered within the fleshy pericarp. It is not covered by a hard coat, like grapes, blueberries, and pawpaws. In North America, drupes and pomes compose most of our tree fruits. Useful terms to remember are stone fruits and pomes, as these two groupings can be discussed categorically; for example, they may have the same disease or pest issues or similar nutritional needs.
Stewardship Practices in Home Fruit Production
The long-term goal of stewardship as presented in Chapter 4 can have many applications in home fruit production. Soil health and quality are central to productivity and sustainability. Growing most fruit crops in home gardens is a long-term effort, and a key element of stewardship is making planting and management decisions that keep crops growing and producing over many years. As a result, management and stewardship steps are a year-round job for home fruit growers, as shown in Figure 5.
Supporting Soil Quality
One of the most important aspects of sustainable production is proper selection of sites and preparation of soil before installing fruit and nut trees, caneberries, and blueberries. Adjusting for the proper pH, adding organic matter, and controlling weeds before planting are critically important to future success.
Cover crops are often used before planting to add organic matter and reduce weed pressure. Often one or more cover crops are planted over many months or even years in sites designated for fruit crops. The use of planted, killed, and tilled-in cover crops has multiple benefits that include increasing soil organic matter, providing plant nutrients, and suppressing weeds before planting.
Cover crops can be carefully used after planting as well, especially in alleyways (aisles between plants or trees). Crop species to be used as living mulches must be carefully selected so they will not detrimentally compete with the main crop for water and nutrients. Cool-season grasses can be beneficial in providing organic matter, increasing water infiltration, and improving soil structure. They may also go dormant in the summer and reduce competition for water. Warm-season grasses are more likely to compete with crops for water. Low-growing legumes can provide soil protection while also contributing their nitrogen fixing capacity. Taller cover crops may require periodic mowing, but the cut biomass can then be used as a killed surface mulch.
Mulching can be beneficial in retaining moisture and reducing weed growth near fruit crops but should be used cautiously or not at all on some crops. In fact, because some crops like blueberry and strawberry are shallow rooted, mulching is often critical to productivity. With all crops, but especially with tree fruit, mulch should be carefully managed to reduce the potential of attracting rodents near the trunk. It is common to apply pea gravel near the base of fruit trees (about 8 to 12 inches around the trunk) to provide a protective barrier. Woven plastic mulches can be used, but they can reduce water infiltration and do not contribute organic matter and soil nutrients.
Many fruit crops require moderate but not high fertility. Sustainable nutrient management relies on carefully applying nutrients to maintain crop health but avoiding overfertilization, which can lead to losses to the environment as well as plant health issues. For instance, applying large amounts of nitrogen leads to rapid growth in apple and pear trees, which can increase the risk of fire blight. Lush growth on other fruit crops can increase the potential for leaf diseases through decreased air flow or reduce fruiting potential.
Supporting Plant Health and Productivity
Reducing the use of conventional sprays in fruit production requires sound knowledge of the insect or disease and a proactive approach. Crop and cultivar selection are essential to success. Selecting crops that are desirable for the gardener as well as appropriate for long-term production on the site and in the location is a key step. Space needs of the mature plants as well as the amount of management time required should be taken into account.
Choosing cultivars that are well-suited to the climate and soils in which they will be grown is also very important. One of the key factors for home fruit growers to consider is disease resistance. Many newer tree fruit cultivars may have resistance to the bacterial disease fire blight as well as some of the most common leaf diseases including powdery mildew, cedar apple rust, and scab.
Proper pruning and sanitation practices are essential to maintaining crop health and productivity. Management of tree growth and vigor is an essential part of management because it can reduce susceptibility to disease. Likewise, vigilance in removing early infections or diseased or damaged fruit, is essential to reducing the spread of disease. Infected leaves (such as those affected by apple scab) can be managed by removing them, covering them with compost, or mowing to accelerate decomposition and reduce the presence of disease inoculum for the next year.
An ever-increasing range of organic, botanical, and biological materials are available for use by home growers in managing pests and diseases. Biological materials include bacteria that can protect from fungal and bacterial infection, clay materials for physical protection, or oil sprays that can control insects or serve as antifeedants.
Pest control decisions should be based on both efficacy and environmental impact. For instance, some organically approved fungicide materials may require more frequent application, which can increase the total amount of material applied. Another consideration is the impact of sprays on beneficial insects and pollinators. An insecticide spray may produce a short-term drop in the insect pest population, but it may also reduce beneficial insect populations, leading to a rapid bounceback of pests. Implementation of sustainable practices requires a wide range of knowledge about pest and disease life cycles and about management and control practices.
Summary
Home fruit production is an increasingly popular aspect of residential horticulture and has the potential to add both beauty and food production to the home landscape. It is important for Extension Master Gardeners to become familiar with information on site selection, planting, and basic management of fruit crops, including the information in the supplemental resources. New varieties and cultivars are continually being tested in Tennessee and nearby states for fruit quality, yield, ease of management, and winter hardiness, so keep up to date on current UT Extension publications.