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 Cultivation.
Most red raspberries (there are also a few with yellow fruit) flower in late spring and the fruits ripen in early to midsummer, depending upon the variety and the weather: such varieties are called standard or summer bearing raspberries. The stems, or canes, are biennial in that they grow vegetatively in their first year, flower and fruit in their second year and then die back to ground level. The root system is perennial and of suckering habit, producing each growing season new replacement canes from adventitious buds on the roots and new buds from old stem bases.
Raspberries Soil and situation Red raspberries grow best on a slightly acid soil of pH 6.0-6.7 that is moisture-retentive but well drained. They can be grown in dry, sandy and limy soils of low fertility, provided plenty of water is given during dry weather and bulky organic manures are liberally applied. Raspberries will not tolerate poor drainage, and even temporary waterlogging can lead to the death of the root system and subsequent death of the canes. In alkaline soils above pH 7.0, iron and manganese deficiencies may occur. The site must be sheltered because strong winds damage the canes and inhibit the movement of pollinating insects. Preferably, they should be planted in full sun, although they grow quite well in partial shade with a minimum of halt a day's sun, provided they are not directly under trees and the soil is not too dry.
Soil preparation
Prepare the ground in late fall or late winter by forking out all weeds, particularly perennials. Then dig a trench along the intended row three spades wide by one spade deep. Cover the bottom of the trench with well-rotted manure or compost to a depth of 3-4 in and fork it into the base so that it is thoroughly mixed with the soil. With double-dug grassland there is no need for this operation because the buried turf takes the place of the organic manure. Finally fill in the trench and fork in a balanced fertilizer such as 10-10-10 at the rate of 3 oz per square yard.
Raspberries Planting and spacing
If possible the rows should run north-south so that one row does not shade another too much. In early spring, plant the canes 18 in apart in the rows. If more than one row is planted, space the rows 6ft apart, or 5 ft apart if using the single fence system. Spread the roots out well and plant them about 3 in deep; deep planting inhibits new canes (suckers). After planting, cut down the canes to a bud about 9-12 in above the ground. Later, when the new canes appear, cut down the old stump to ground level before it fruits. This means foregoing a crop in the first summer but it ensures good establishment and the production of strong new canes in subsequent years.
Supporting the canes
To prevent the canes from bowing over when heavy with fruit and to keep the fruits clean it is generally advisable to support the canes. The usual method is a post and wire fence for which there are various alternative systems. It is easier to erect the fence before planting, although it may be left until the end of the first summer.
Single fence: vertically trained canes This is the most popular method and consists of single wires stretched horizontally at heights of 21/2, 31/2 and 51/2ft. It requires the least space of the various fencing systems and is ideal for the small garden. The fruiting canes are tied individually to the wires and thus are secure against winter winds. They are exposed to the sun, which enhances the quality of the fruits and reduces the incidence of fungal disease. The system has the disadvantages that the new canes are at risk of being trampled on during picking and of being damaged by strong winds in July unless temporarily supported by string tied to the lower wires. Drive in preserved 71/2 ft posts 18 in into the ground 12-15 ft apart. Use 14 gauge galvanized fence wire. Erect the end posts first and strut them and then drive in the intermediate posts. Finally fix the wires to the posts using straining bolts at one end and staples on the intermediates and at the opposite end. Double fence: parallel wires The double fence is erected in a similar way to the single fence but because the top wires are not as high, the posts are only 61/2 ft tall. Cross bars 21/2 ft long by 2 in across to carry the parallel wires are fixed to the end posts and to the intermediate posts. In exposed situations, double posts should be used instead of cross bars. Parallel wires are spaced 2 ft apart at 3 ft and 5 ft from the ground. Stretch wire as cross ties every 2 ft along the wires to prevent the canes falling down in the row. This method has the advantage of enabling a larger number of canes to be trained in and a greater yield to be obtained from much the same area. Picking the fruits from the center is difficult, however, and there is a higher risk of fungal diseases because of the more crowded conditions. In an exposed garden the untied canes may be damaged on the wires, so the canes should be tied to the wires.
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