Cultural Tips for Growing Strawberry

Site Selection

Plant your garden in a convenient location, where you can check it frequently. Choose an area near an abundant supply of water so you can water as needed easily. Vegetables do best if they receive full sunlight (at least 4 to 6 hours a day). Plant them in a well-exposed area in the garden, where they are not shaded by trees, fences, or walls. Try to plant away from areas that will be watered by lawn sprinklers.

Whenever possible, select a location that is not heavily infested with weeds, especially weeds such as field bindweed, nutsedge, and bermudagrass which can be hard to control with hand weeding. Also avoid areas that have had previous disease problems.

Try to plant on level ground. Level ground is easier to work on than sloping ground. Vegetables will do well on a wide range of soils; they do best in well-drained soils. If your soil forms a clump when squeezed, then it is too wet; if the soil crumbles easily, it is a good soil to use. Damp soil surfaces encourage snails, slugs, sowbugs, and root diseases; fruit decay and leaf spot diseases may also increase. Soil amendments can make clay and sandy soils easier to work with, and correct soil preparation can improve poor soil.

Adding organic matter (compost, peat moss, manure, sawdust, ground bark) makes clay and sandy soils easier to work with. The soil should be kept at a pH level of 6.0 to 6.5. Lime or gypsum can be added to soils low in calcium.

Soil Improvement

Any type of soil can be improved with soil amendments. Heavy clay or sandy soils can be improved by adding organic material such as compost, manure, or leaf mold. Texture is an important consideration when choosing an amendment. An amendment that is granular and fine grained is important for container mixes. For gardens, a more coarse-grained amendment can improve drainage and aeration. Work amendments into soil by rototilling, raking, or double-digging.

Soil Preparation

The preparation of your soil is just as important as adding fertilizer and soil amendments. Before working the soil, make sure it is moist but not thoroughly wet.

1. Use a shovel, rototiller, metal bow rake, or all of them together to loosen the top 1 to 2 inches of soil. Rake the area to remove weeds and old crop debris. Be sure to dig out roots.
2. Irrigate the plot deeply to encourage the germination of weed seeds.
3. In a week or two, after a substantial number of weeds have germinated, work the area again to kill the weed seedlings. Be sure to break up the clods in the soil, as seeds planted in cloddy soil will germinate poorly and won't live long because the soil dries too quickly.

Bed Preparation

After the soil is prepared, make raised beds about 6 inches high and about 10 inches wide across the top if you are planting one row of strawberries, or 18 inches wide if you are planting two rows. Two rows of plants work well, and you can run a drip line down the middle of the bed between them. Orienting the beds in a north-south direction provides the best sunlight exposure for the plants. Make sure the furrows between beds are sloped enough in the direction of the rows where water drains away during rainy weather. Standing water promotes root and crown diseases. If you are planning to water the strawberries by flooding furrows, make the slope shallow enough so furrows can be filled with water by blocking the ends. Make planter boxes at least 12 inches deep so plants will be rooted entirely in the soil you use to fill the box. Put copper barriers in place around the box as soon as it is filled with soil to keep snails and slugs from crawling in. If you have problems with moles or gophers, place a wire mesh barrier beneath raised beds before you plant.

Time to Plant

Middle to late August generally is the best time to plant strawberries in all locations. Day-neutral cultivars also can be planted in the fall or in February and March. Where winters are mild, short-day cultivars can be planted in November using green plants--new plants that you dig in October.

When you plant affects fruit production the following year. Short-day cultivars planted in August yield a small crop of fruit in the fall and begin their main fruit production the following spring. You may get better spring fruit production if you remove all the blossoms produced the first fall after planting. Day-neutral cultivars begin fruit production in the fall and continue as long as temperatures are favorable. For both short-day and day-neutral plants, heaviest production is in May and June. Healthy summer plantings yield about 1 quart of berries per plant. Fall plantings yield about 1 pint. Fruit production is usually highest in the first full season after planting and declines afterwards.

Recommended Planting Dates for Strawberries in California
Short-Day Cultivars
Area	Summer plantings	Winter plantings
Central Coast	Aug. 15–Sept. 5	Oct. 15–Nov. 5
Santa Maria Valley	Aug. 15–Sept. 15	Oct. 1–Nov. 30
Oxnard Plain	not grown	Oct. 10–Nov. 10
South Coast	not grown	Oct. 10–Nov. 1
San Joaquin Valley	July 20–Aug. 5	not grown
Day-Neutral Cultivars
Area	Summer plantings	Winter plantings
Central Coast	Sept. 25–Oct. 10	Oct. 25–Nov. 26
Santa Maria Valley	Feb. 15–June 15	Oct. 20–Nov. 30
Oxnard Plain	not grown	Oct. 10–Oct. 25
South Coast	not grown	Oct. 10–Oct. 25

Planting

Strawberry plants can be obtained from local nurseries. Replace your plantings with new plants from a nursery every 2 to 3 years.

You can start new plants from your existing strawberries by letting runners set daughter plants into clean soil in late summer. Be sure to start daughter plants only from healthy mother plants and remove all parts of the mother plants after the daughters are started. Dig up these new plants in October, shake the soil from their roots, remove all but two healthy leaves, and place them in thin plastic sandwich bags. Hold them in a refrigerator for 10 to 15 days, then plant them into clean, prepared beds.

When planting, make sure to spread the roots out before firming the soil around the plant. Keep the growing point above the soil line. Space plants about 12 inches apart in each row with rows about 12 inches apart in two-row beds, and stagger the plants in the two rows to give them maximum growing room. In single-row beds, space plants about 10 inches apart.

Rotating Plantings

A number of pest problems carry over from one season to the next and gradually worsen over a period of years. It is a good idea to replace plantings with new plants at least every 3 years or whenever plants begin to decline from pest attack. Switch to new planting beds or treat the planting bed between strawberry plantings to reduce pest populations before replanting.

It is best to start with new plants from certified nurseries if you can get them. You can start your own new plants by allowing runners to set plants during the second or third season of the old planting. Set the runners into clean soil. Remove the old plants when the new ones are established.

If rotating with other planting locations in your garden, it is best to avoid following crop plants that are susceptible to Verticillium wilt, such as tomato, potato, eggplant, and cucurbit. Sweet corn is a good garden rotation for strawberries. If you allow a planting bed to lie dormant between strawberry plantings, plant ryegrass to reduce levels of Verticillium and to keep other disease organisms from building up.

Possible Rotation Sequences

1. Remove old strawberry plants in late summer.
2. Plant a winter crop of cauliflower, cabbage, or another crucifer.
3. In spring, spread all crop residue from the crucifer over the planting area, allow it to dry and rototill it in.
4. Solarize the soil in summer.
5. After removing plastic film at end of summer, water the treated area regularly for two months.
6. Plant new strawberries in late fall or late winter.

Variations

As an alternative to steps 2 and 3, plant a winter crop of ryegrass and rototill it in with dried crucifer residue collected from another area of the garden.

As an alternative to steps 5 and 6, follow solarization with ryegrass, rototill in spring, and plant in August.

Watering

Drip irrigation works best for strawberries once plants have formed several leaves. It helps prevent diseases and insect problems. Place a drip line or drip tape between rows of plants if you have two rows planted on each bed or alongside plants of single-row beds. You can place drippers appropriate for the soil type (1 or 2 gallons per hour rate for well-drained sandy loam soil) about 2 inches (5 cm) away from the crown of each plant. Run the drip system twice a week, long enough to wet the planting bed thoroughly.

Furrow irrigation also can be used for raised bed plantings. Make rows no longer than 20 feet (6 meters). Dam the ends of the furrows between planting beds, then fill each furrow half to two-thirds full with water and let it soak into the bed. Repeat furrow irrigation weekly. Be sure to remove the dams at the ends of furrows after the beds have been thoroughly wetted, so water can drain away from the planting beds.

If salt accumulation becomes a problem, use sprinklers to rinse salts from the beds. Sprinkle heavily at least twice during the summer; in the morning so plants can dry off.

Pruning

For best results with your garden strawberries, remove runners to encourage single plants to produce several crowns. During the first year of your strawberry planting, allow a few runners to form daughter plants, which can be used to replace any plants that die. Remove all other runners as they begin to form. Keep them removed during the life of the planting unless you want to start new plantings from them. If growth of day-neutrals is weak after they are planted, cut off the first two flower clusters that form, which increases the vigor of the plants.

Prune off most leaves from short-day plants in the late fall after the first full year of growth. From day-neutrals, remove the older leaves that are turning color. Be sure to remove any leaves that show signs of disease. Collect all prunings and discard them well away from the planting; they can be a source of disease inoculum.

Fertilizing

The first step in any fertilization program is to give the roots of the newly set-out plant ready access to a generous supply of phosphorus to encourage development of a good root system. All commercial fertilizers are labeled by the percentages of nitrogen (N), phosphorus (P), and potassium (K). After planting, nitrogen is more important and should be lightly and frequently applied, for example, every 4 weeks, to maintain healthy, productive plants.

Strawberries are not heavy nutrient feeders. Begin with a starter fertilizer when you plant. At each planting spot, open a hole 6 to 7 inches deep with a trowel, place 1 teaspoon of slow-release fertilizer, ammonium phosphate, or ammonium sulfate in the bottom of the hole, and cover the fertilizer with about 1 inch of soil. Place the plant on top and firm the soil around the plant. Use approximately 2 pounds of 10-20-20 or 4 pounds of 5-10-10 per 100 sq. feet.

Add slow-release fertilizer in February, just before putting on plastic mulch. About 2 inches to the side of each plant, make a hole 3 to 4 inches deep and put 1 heaping teaspoon of the fertilizer in the hole and fill it back with soil. Add fertilizer again in the summer if the plantings are to be carried over another year.

Fertilizing Tips

1. Begin with a starter fertilizer when you plant. Do not use a starter fertilizer if you added ammonium fertilizer to augment soil solarization.
2. Add slow-release fertilizer in February just before putting on plastic mulch. It should be high in ammonium nitrogen.
3. Add fertilizer again in the summer if the plantings are to be carried over another year.

Harvesting

Picking fruit at the correct stage of ripeness greatly reduces postharvest losses. Harvest when fully ripe or when pink to three-fourths colored. Overripe fruit is more easily damaged and decays more quickly after harvest. Leave the calyx and stem on fruit to help prolong its shelf life.

Handle fruit carefully during harvest and discard all overripe fruit and any fruit with signs of decay; decay spreads quickly in flats of harvested fruit. To maintain fruit quality, increase shelf life, and decrease losses to decay, provide shade for fruit held in the garden, protect fruit from warm winds, and remove fruit from the garden within 1 to no more than 2 hours following harvest.