Growing Strawberries in
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strawberries are native to all northern temperate climates and
Local commercial farms use similar methods to produce a very early crop starting in early to mid winter. The early crop commands the highest prices. Nearly all use conventional chemicals. A few farm organically, but organic methods rarely produce a crop before spring.
Strawberry plants require good to excellent drainage and perform best in sandy loam or loamy sand. They will perform in heavier soils if the bed is raised high enough to create better drainage. Local farms raise the soil about 18 inches which also make harvesting easier. Drip irrigation lines are installed for high efficiency and to keep the foliage and fruit dry. From this point conventional farming techniques are quite different.
Conventional soil preparation
To promote an artificially early crop the rows are covered with clear plastic. The clear cover traps the sun’s energy and the soil stays quite warm. To prevent weed seed from germinating and competing with the crop the soil must be fumigated. The irrigation lines distribute fumigation chemicals underneath the plastic and in 5 days all seeds, diseases and bugs are killed. The plastic is then cut between the beds and the fields will be ready to plant 2 weeks later. Without fumigation the strawberry plants couldn’t be planted every year and the use of transparent plastic mulch would be disastrous.
Organic soil preparation
On organic farms, only a fraction of the land is planted with strawberries at a time. Unrelated crops are rotated to avoid a buildup of pest or disease problems in any one location. A crop of legumes (beans, peas, or alfalfa) will increase the soils nitrogen and a crop of broccoli seems to discourage a root disease (Verticillium).
Weeds are a major problem. Weed competition can dramatically lower production. Some organic farms weed constantly, some cover the soil with black plastic, some apply a surface mulch. All options are a significant expense, but higher prices for organic produce usually offsets the cost.
Black plastic prevents about 90% of the weeds, but doesn’t warm the soil as much as a clear plastic mulch.
Installing the Plants
All farms acquire and install bare root plants. These plants come pre-chilled. All strawberry plants need a period of winter chill between 34°F and 55°F to initiate vigorous growth and complete development of flower buds. Too little chill results in poor growth and a plant too weak to produce much. Too much chill results in a plant with super vigor, but delayed production. The farmer must guess how long they should refrigerate the bare root plants to balance the chill that they will naturally receive during winter following installation.
All farms use tractors to punch a deep hole into the bed (through the plastic mulch) at regular intervals. The workers then place each plant with its crown at soil level and firm the soil around the roots to hold it in place. The bed is then watered thoroughly with sprinklers to properly settle the plants. Once established the farms then use the soaker tubing for irrigation.
Local Farms Replant Annually
In order to get the early harvest, local farmers must install prechilled plants every year. Strawberry plants can produce for 3-4 years, but without clear plastic mulch and prechilling, the plants won’t produce until spring.
Farms usually consult with soil labs to provide proper nutrition, however, strawberry plants do fine with levels of nitrogen, phosphorus and potassium that are fairly even. For short term results Osmocote 14-14-14 is fine. For long term results use organic fertilizers.
Berries are ready to pick about 4-5 weeks after blooming commences. It is best to pick off the first stalk of flower buds to allow the plant to build strength before production begins. Workers are sent through each field 2-3 times per week to pick ripe berries. To maximize shelf life the berries are gently picked, not allowed to get wet, and cooled immediately.
Growing Strawberries at Home
A typical strawberry plant can produce fruit for 3-4 years. On young plants remove the first set of flowers so that the plant can gain size and strength before production begins. A single, well-developed plant can grow over 18-inches wide and 10-inches high.
Strawberry plants should be located in sun (1/2 day is minimum) and planted in well-drained soil. Heavy soils should be elevated into substantial mounds or raised beds to improve drainage. Plants are placed 12-18” apart.
Strawberry plants can be purchased any time of the year in containers or as bare root. Bare root plants are more commonly planted during mild weather late fall through spring.
Strawberry plants perform quite well in pots. The berries are hanging over the edge but not touching the ground. This gives them some protection from birds, slugs, snails and pillbugs. You can grow a single, full-size plant in an 8-inch container. Our Laguna Hills Nursery custom potting soils, ACID MIX and TROPICAL POTTING SOIL are superb. Most commercial potting soils will provide mediocre results. Perhaps the best potting soil is construction sand. Our favorite soil in containers is a mixture of sand with ACID MIX.
Strawberry plants require ample moisture at all times. Plants that get severely dry often don’t recover until the following year. Small pots placed in deep saucers filled with water can last a week on a single irrigation. The “moat” that is created will also guard against snails, earwigs and pillbugs.
During summer most plants produce baby plants on long stems called “runners”. These baby plants will grow roots where they touch the soil. These can be removed to increase production of berries or saved to increase the number of plants. The baby plants start production the next year. Do not allow too many plants to grow. Try to keep them a minimum of 6-inches apart on center. Older plants and dead plants can be removed to make room. Results are improved greatly if several handfuls of soil are also removed and replaced.
Strawberry plantings require crop rotation, just like any other crop.
The plants that grow from runners are clones and genetically identical to the parent. Strawberry plants will also grow from seed, however these will be genetically different.
Strawberry varieties can be classified as to when they bear fruit and how they grow.
day) varieties are most common.
They generally have the largest, highest quality berries and are the
most productive. They
also produce the most runners during summer.
Camarosa This is a popular commercial variety with high yield and large to very large firm fruit of good flavor. Mildew may be a problem.
Palomar A new commercial variety for local growers that has excellent flavor. The flesh is firm.
This variety set the standards for flavor and sweetness in
Ventana Similar to Camarosa with slightly larger fruit and slightly better flavor (considered very good).
Everbearing & Day Neutral
These varieties produce continuously, although heaviest in summer and sporadically through fall. Mild coastal conditions promote more constant production. High temperatures inhibit flower production.
San Andreas Similar to
Seascape The fruit are large and attractive with glossy skin and very good flavor. This variety resists many viral diseases and is highly productive.
These small, clump-forming, plants produce small (tiny), highly fragrant berries over a long period during warm weather. These can be grown from seed or divisions.