Cultivation

Strawberry varieties vary remarkably in size, color, flavor, shape, degree of fertility, season of ripening, liability to disease and constitution of plant. Some vary in foliage, and some vary materially in the relative development of their sexual organs. In most cases the flowers appear hermaphroditic in structure, but function as either male or female.

For purposes of commercial production, plants are propagated from runners and generally distributed as either bare root plants or plugs. Cultivation follows one of two models, annual plasticulture or a perennial system of matted rows or mounds. A small amount of strawberries are also produced in greenhouses during the off season.

The bulk of modern commercial production uses the plasticulture system. In this method, raised beds are formed each year and covered with black plastic, which prevents weed growth and erosion, under which is run irrigation tubing. Plants, usually obtained from northern nurseries, are planted through holes punched in this covering. Runners are removed from the plants as they appear, to encourage the plants to put most of their energy into fruit development. At the end of the harvest season, the plastic is removed and the plants are plowed into the ground. Because strawberry plants more than a year or two old begin to decline in productivity and fruit quality, this system of replacing the plants each year allows for improved yields and more dense plantings. However, because it requires a longer growing season to allow for establishment of the plants each year, and because of the increased costs in terms of forming and covering the mounds and purchasing plants each year, it is not always practical in all areas. The other major method is to maintain the same plants from year to year. The runners of established plants should be allowed to root in the soil adjoining the plants, which should, therefore, be kept light and fine, or layered into small pots as for forcing. As soon as a few leaves are produced on each the secondary runners should be stopped. When the plants have become well-rooted they should at once be planted out. They do best in a rather strong loam, and should be kept tolerably moist. The ground should be trenched 50-100 cm deep, and supplied with plenty of manure, a good proportion of which should lie just below the roots, 25-30 cm from the surface. The plants may be put in on an average about 50-60 cm apart.

The plantation should be renewed every second or third year, or less frequently if kept free of runners, if the old leaves are cut away after the fruit has been gathered, and if a good top-dressing of rotten dung or leaf mold is applied. A top-dressing of loam is beneficial if applied before the plants begin to grow in spring, but after that period they should not be disturbed during the summer either at root or at top. If the plants produce a large number of flower-scapes, each should, if fine large fruit is desired, have them reduced to about four of the strongest. The lowest blossoms on the scape will be found to produce the largest, earliest and best fruits. The fruit should not be gathered until it is quite ripe, and then, if possible, it should be quite dry, but not heated by the sun. Those intended for preserving are best taken without the stalk and the calyx.

A mulching of straw manure put between the rows in spring serves to keep the ground moist and the fruit clean, as well as to afford nourishment to the plants. Unless required, the runners are cut off early, in order to promote the swelling of the fruit. The plants are watered during dry weather after the fruit is set, and occasionally until it begins to colour. As soon as the fruit season is over, the runners are again removed, and the ground hoed and raked.


Fragaria × ananassa 'Chandler' , a short day commercial variety grown in California.Strawberries are often grouped according to their flowering habit. Traditionally, this has consisted of a division between "June-bearing" strawberries, which bear their fruit in the early summer and "Ever-bearing" strawberries, which often bear several crops of fruit throughout the season. More recently, research has shown that strawberries actually occur in three basic flowering habits: short day, long day, and day neutral. These refer to the day length sensitivity of the plant and the type of photoperiod which induces flower formation. Day neutral cultivars produce flowers regardless of the photoperiod. Most commercial strawberries are either short day or day neutral.

While rarely if ever done commercially, strawberries may also be propagated by seed, and a few seed propagated cultivars have been developed for home use. Seeds are acquired commercially or saved from fruit ripened early in the summer. They may at once be sown, either in a sheltered border outdoors or in pots, or better in March under glass, when they will produce fruits in June of the same year. The soil should be rich and light, and the seeds very slightly covered by sifting over them some leaf-mould or old decomposed cow dung. When the plants appear and have made five or six leaves, they are transplanted to where they are to remain for bearing. The seeds sown in pots may be helped on by gentle heat, and when the plants are large enough they are pricked out in fine rich soil, and in June transferred to the open ground for bearing.