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Growing Strawberries in Your Home Garden
EC 1307 Do you want to print a copy? We recommend downloading the print version (155 K). First download the free Adobe Reader, if you don't already have it. ContentsSelecting a site Growing strawberries in your home garden can be an interesting and rewarding experience. By growing various cultivars (varieties) of strawberry you can pick ripe fruit from late spring until frost in the fall. If you care for plants properly, you can obtain enough berries for your family from a relatively small area. Selecting A SiteStrawberries require direct, full sunlight for best production. They bloom early in the spring, so don't plant them in frost pockets--low-lying areas into which cold air drains or areas (surrounded by tall trees, for example) where cold air is trapped. Avoid planting where tomatoes, peppers, potatoes, eggplant, strawberries, raspberries, or blackberries have grown in the past 3 years. These plants can all act as hosts for fungi, such as Verticillium wilt, and insect pests that build up in the soil unless you place these crops on at least a 3-year rotation schedule. Strawberry plantings can remain productive for 3 to 4 fruiting years. You can minimize the buildup of many insect and disease problems by rotating the strawberry patch from one site to another each time you make a new planting. Soils. A well-drained loam soil, high in organic matter, is ideal. Avoid planting in heavy clay soils. If your soil is sandy, pay more careful attention to watering and fertilization. However, strawberries will tolerate a wide range of soil types if you properly modify the soil. You can improve most garden soils by adding organic matter. The soil should be well-drained--strawberries can't tolerate standing water or "wet feet." If the only soil you have available has poor drainage, you may be able to improve it by tiling and adding organic matter. Planting on ridges or raised beds also helps if soils drain poorly (see "Preparing the soil" and "Planting systems"). Selecting a CultivarStrawberry cultivars are normally placed in one of three categories (or types), based on their responses to day length (photoperiod) and the season in which they produce a crop: June-bearers, everbearers, and day-neutrals. June-bearers produce one crop a year, usually from early June to July. These plants produce flowers, fruits, and runners (daughter plants produced on aboveground stems) in sequence. Most commercial plantings are of June-bearing cultivars. Everbearing types produce two crops a year, one in June and one in the fall. Everbearers usually produce few runners. Day-neutrals produce a relatively continuous crop throughout the growing season. The fruit of everbearers and day-neutrals is typically smaller, and total seasonal yields are often lower, than that of June-bearers. However, the advantage in growing these types along with the June-bearers is that you can harvest fruit for most of the growing season. Strawberry cultivars are very much adapted to certain climatic conditions. Cultivars that haven't been tested in Oregon or that aren't adapted to this region aren't recommended.
June-bearers Sumas. Season: early to mid. Fruit: large with medium-red, bright, glossy external and internal color; easy to cap but less firm than Totem. Hood. Season: early to mid. Fruit: large, bright, red, firm and easy to cap; poor texture for freezing but very good for preserves and suitable for fresh; plants are susceptible to
Shuksan. Season: mid. Fruit: large, glossy, bright red with a tough skin; firm and not as easily capped as Olympus and Hood; good quality for frozen pack and preserves; suitable for fresh. Totem. Season: mid. Fruit: large, attractive, dark red with uniform red internal color; caps easily, firm; good for frozen pack and fresh; a little dark in color for best preserves. Olympus. Season: mid. Fruit: small to medium, bright red throughout, moderately firm; good for frozen slice pack and preserves; unacceptable for fresh market. Benton. Season: mid to late. Fruit: large, medium bright red color on exterior with moderately good red internal color; medium firm with mild flavor; doesn't cap as easily as Hood; preserve quality is similar to Hood. Rainier. Season: late. Fruit: large, bright red throughout; ripens late and difficult to cap; excellent for frozen pack, preserves, and fresh. Everbearers Fort Laramie. Fruit: moderate fruit size, bright scarlet red and firm-fleshed; interior flesh is pink to scarlet; flavor is sweet. Ozark Beauty. Fruit: large, sweet and good flavored; exterior color and flesh are bright red. Quinault. Season: crops slightly in June and then moderately to heavily in July to September. Fruit: large (up to 2 inches in diameter), solid crimson in color and glossy with a light interior that's soft to slightly spongy; large berries have an open center; somewhat difficult to cap; flavor is fair; poor for freezing and jam. Day-neutrals Fern. Fruit: larger and of better quality than Hecker; earlier fruiting than Hecker. Hecker. Fruit: medium, dark reddish orange; flavor and quality equal or superior to other earlier California introductions. Selva. Fruit: large with slightly dark, bright, attractive skin; very firm; good flavor when ripe. Tillikum. Fruit: small to medium with a glossy dark red skin and bright red flesh; average firmness. Tristar. Fruit: small to medium, firm, glossy, deep red with good flavor.
Establishing Your PlantingPreparing the soil. A good supply of organic matter in the soil improves aeration and drainage and increases water-holding capacity. You can apply organic matter the summer or fall of the year before you plant; manure applied at 2 to 3 bushels per 100 ft2 is a good source. You can also use compost, leaves, chopped hay or straw, peat moss, sawdust, etc. Take care to use only materials that you think are free of insects and weed seeds. Dig, plow, or rototill the material into the soil to ensure that it will be well decomposed (rotted) by planting time the following spring. If you incorporate large amounts of nondecomposed (fresh) material into the soil, add ammonium nitrate (33% nitrogen) at 1 lb per 100 ft2 to aid in decomposition. Eliminate all perennial weeds the year before you plant. Don't let weeds to go to seed! The site you select and prepare should drain well. However, if drainage is poor, you can form ridges or raised beds. Mix organic matter, coarse sand, and fertilizer (see below) with the soil. Shape ridges or raised beds 8 to 10 inches high. Make ridges wide enough to grow a single row of plants; raised beds should be wide enough to accommodate double-or triple-wide rows in the hill system (see "Planting systems"). Fertilizing. Before you plant, apply 1 lb of 10-20-20 fertilizer per 100 ft2 . If you use a fertilizer with a different ratio, apply it on an equivalent basis -for example, 2 lb of 5-10-10 per 100 ft2 . Work the fertilizer into the upper 6 inches of soil. If you're going to set plants on ridges or raised beds, calculate only the area of the bed when incorporating fertilizer. If you used manure to improve soil structure, decrease the rate of fertilizer you apply by one-half. Planting. When you plant or replant strawberries, begin with certified disease-free plants purchased from a reputable nursery. Avoid using runner plants from an old, established patch--they're often diseased. Strawberries are subject to several virus diseases that are transmitted to the new runner plants, mainly by aphids. Purchase plants just before planting. If you can't plant right away, store plants for a short period in a closed plastic bag in the refrigerator (34 to 40°F) or you can temporarily "heel" them into the soil. To heel in plants, dig a shallow trench that's deep enough for the roots. Place plants in a single layer against one side of the trench with crowns (short stem of the strawberry plant) partially above the soil line. Cover roots with soil and gently firm it in place. Water the soil. Keep plants moist before you plant, and plant in a damp, well-tilled soil. Don't leave plastic bags containing plants in the sun. If possible, plant on a cool, cloudy day. Plant strawberries in early spring, as soon as you can prepare the soil. Use a spade, shovel, or trowel to set the plants. Dig a hole for each plant large enough to place the roots straight downward but somewhat spread. The midpoint of the crown should be level with the soil surface; the topmost root should be just below the soil surface (Figure 1). If you set plants too high, the roots may dry out. If you set them too low (Figure 1), the growing tip at the top of the crown may be smothered and rot. Fill the hole with soil and press firmly around the roots-take care that no air pockets remain. Irrigate the plants as soon as you set them.
Planting systems. The matted-row and hill systems are the most common training methods for strawberries. The hill system is preferred for everbearers and day-neutrals, because they don't produce as many runners as June-bearers. June-bearers are usually grown in a matted row, but you can also grow them in a hill system. In the matted-row system, set plants 18 to 24 inches apart in the row (or raised bed), with 3 to 4 feet between rows (figure 2). Allow the runners that form from these "mother" plants to develop and root--they'll form a matted row 18 inches wide. Keep the remaining 1.5 to 2.5 feet between rows clear by sweeping earlyformed runners into the row or by cutting off late-formed runners that grow into the aile or off the edge of the raised bed.
The hill system is ideal for cultivars that produce few runners, such as everbearers. Set plants 12 to 15 inches apart in double-or triple-wide rows (on raised beds if necessary). Aisles should be 1.5 to 2 feet wide (Figure 3) . Remove all runners that develop throughout the growing season before they root.
First Season's CareBlossom removal. In June-bearers, remove all flower clusters during the planting year before fruit is formed. Be patient! If you try to produce strawberries during the planting year of June-bearers, you'll stress the young plant. This limits crown and leaf growth, which will decrease the yield you get the following season. In everbearers and day-neutrals, remove only the first flush of flowers, allowing flower clusters formed after July l to develop fruit. This allows plants to get well established before fruiting. Runner removal. Cut off all runners every 2 to 3 weeks from plants growing in the hill system. In the matted-row system, the majority of the following season's crop will come from the mother plants plus runners that develop and root before August. Ideally, you should position runner plants as they develop to attain a density of about 5 runner plants per square foot of matted row. Place a small amount of soil just behind a runner plant to keep it in place. Once you achieve this density remove all other runners. (This is quite labor-intensive.) Another method is simply to remove all unrooted runners from the matted row from September 1 through the fall, when runner production ceases. Matted rows that are too dense produce lower yields of smaller berries, have a larger proportion of misshapen berries, and have a higher incidence of disease. Cultivation and weed control. Weeds compete with the shallow-rooted strawberry plant for water and nutrients, and they often harbor insects and diseases. Hoe around the plants often enough to destroy weeds and to keep the soil loose. This promotes good growth and permits runner plants to root quickly when establishing the matted row. Check with your county office of the OSU Extension Service or a local garden supply store for herbicides registered for use on strawberries in home gardens. You can use sawdust, bark, or black plastic mulch in
the row to keep down weeds, conserve moisture, and keep fruit
clean. However, mulches may lead to an increase in slugs.
Mulch is particularly useful for hill-system plantings. Avoid covering the top of the crown or growing point of plants with sawdust or bark mulch. Black plastic is very useful. Clear plastic isn't as suitable--weeds grow underneath it. You can apply plastic most easily just before or just after planting. Before planting, place the plastic over the planting area or raised bed. Edges of plastic should overlap and be held down with soil. Cut circles with a diameter of 6 inches in the plastic where you'll set the plants. Plant through these holes. If you lay plastic just after you plant, feel for the plants under the plastic and carefully cut holes around them. The holes cut in the plastic do allow some weeds to grow around the plants, but they're necessary to ensure that plants get enough water and for fertilization. You can place a thin layer of bark mulch on the plastic to make the planting look more attractive. Runner plants can't root through the plastic, but you should still cut them off plants growing in the hill system.
Fertilizing. You may add additional nitrogen fertilizer 6 weeks after planting if plant growth is weak and leaves are light green. Broadcast ammonium nitrate (33% nitrogen) at a rate of 0.5 lb per 100 sq ft of row. Make a similar application in late July or early August if the plants lack vigor. Broadcast the fertilizer when the foliage is dry--it sticks to wet leaves and can easily burn. Avoid broadcasting ammonium nitrate directly on crowns, or they may burn. You can remove fertilizer from plants by brushing and using sprinkler irrigation. You may also band fertilizer 2 to 3 inches from both sides of the row and 2 to 3 inches deep. If the soil is dry, it may be necessary to irrigate, to carry the fertilizer into the soil and to prevent toxic concentrations from forming.
Watering. Strawberries are shallow rooted. To obtain maximum growth and yield, they should never be stressed by lack of water. Keep newly set strawberry beds well irrigated throughout their first season. If you plan to develop a matted row, the earlier you can root down the runner plants, the more fruit buds they'll form for the following year's crop. If you're maintaining plants as individuals in the hill system, the larger and more vigorous their crowns, the more fruit buds they'll set in late summer and fall. Care of Established PlantingsWinter and frost protection. In western Oregon, strawberry plants seldom need to be protected from winter cold. However, in areas east of the Cascades, it may be necessary to protect your plants from severe winter temperatures. Strawberry crowns and flower buds may be damaged or killed at temperatures colder than 22°F and persistent alternate freezing and thawing can lift plants out of the soil. You can minimize this damage by covering plants with 2 to 3 inches of loose straw after temperatures first drop below freezing. Remove straw once the risk of severely cold temperatures has passed. It's important to avoid placing straw on the plants too early or leaving it on too late in the spring. Strawberry flowers may be killed if frost occurs during bloom. Frost-damaged flowers have black centers and produce either misshapen fruit or no fruit at all. If frost is forecast during bloom, protect a small strawberry planting by placing a sheet of spunbound polyethylene or light canvas over the plants. Place the cover on in the early evening and remove it in the morning once the risk of frost injury has passed.
Weed control and cultivation. Keep the planting free of weeds by cultivation. Check with your county office of the OSU Extension Service or a garden supply store for herbicides registered for use on strawberries in the home garden. Fertilizing. It's best to fertilize established strawberries in late summer to promote fall growth. Spring fertilization results in excessive leaf growth and runner formation and doesn't promote more or larger berries. After harvest, apply 2 to 3 lb of 10-10-10 (or equivalent well-balanced fertilizer) per 100 sq ft of row. Foliage should be dry. If you aren't mowing the plants (see "Renovation"), brush or wash the fertilizer off the leaves. You can also band fertilizer 2 to 3 inches from both sides of the row and 2 to 3 inches deep. Water the plants to carry the fertilizer down to the roots. Watering. During the growing season, strawberries need about 1 inch of water per week. On sites with sandy soils or during very hot weather, plants may need more water. If rainfall isn't adequate to supply the necessary water, irrigate the plants. Wet the soil to a depth of 6 to 8 inches with each irrigation. Avoid applying so much water that the soil remains saturated (excessively wet) for long periods. Standing water is harmful, even for a day or two. After the first season, there are two critical times when good soil moisture is important. The first is from bloom through harvest, to ensure the berries swell to maximum possible size. The other is from late August through early fall, when plant growth resumes and flower buds for the following season's crop are formed. Renovation. You can maintain a strawberry planting for several fruiting seasons if you properly manage and renovate it after harvest. If plants are vigorous and relatively free from weeds, insects and diseases, you may renovate a matted-row bed of June-bearers to prepare it for the next season. This is not recommended for day-neutrals or everbearers.
To renovate June-bearers in the hill system, mow off foliage above the crown, remove and burn or bury all plant debris, and remove all runners through the fall. Remove all plantings that are no longer productive or lack vigor. If you want to make a new planting, plant in another location.
Starting the last producing year of an older planting prevents a gap in fruit production. Most plantings remain productive for 3 or 4 fruiting years. Novel Growing MethodsYou can also plant strawberries in barrels, planters, or hanging baskets. These plantings require close care in watering, fertilizing, and other cultural requirements. You may find fruit production in hanging baskets disappointing. Everbearing or day-neutral types are best suited for container production. The containers you choose should be well-drained. A possible soil mixture consists of 1 part sand, l part peat moss, and 2 parts garden soil. You can replace the peat moss with well-rotted manure or compost. Mix about 0.5 cup of complete fertilizer, such as 10-20-20, into each bushel of the growing medium. HarvestPick fruit every other day or daily during hot weather. Fruit harvested in the morning usually has a longer shelf life. Pick all ripe berries--fruit left on the plant become overripe, which promotes development of disease and insect problems. You can refrigerate fruit for several days. Avoid washing fruit until just before you use it, to prevent softening and decay. PestsIf any diseases or insect pests become a problem--such as weevils or aphids--check with your county office of the OSU Extension Service for management recommendations. The incidence and spread of fruit rot may be decreased by preventing a matted row planting from becoming too dense and by picking and discarding infected fruit. Prepared by Bernadine C. Strik, Extension horticulture specialist, Oregon State University. Reprinted April 2002. |
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