Raspberries ripen shortly after strawberries and make an excellent small fruit crop for summer and fall depending on the cultivars selected. Two years are required to establish a raspberry planting, but once established, the planting can remain productive for several years if given good care.
Types and Varieties
Raspberries may be classified by fruit color and/or fruiting habit. They may be red, black, purple, or yellow-fruited types. The red raspberry is first to ripen, followed by the black, purple, and yellow cultivars. Compared with black raspberries, red raspberries tend to be more cold hardy, have larger berries, and have more erect canes. Black raspberries are less cold hardy; have smaller, seedier, and more aromatic berries; and have arching canes. Purple raspberries are hybrids of red and black raspberries and tend to respond in growth habit similar to black raspberries. Most yellow raspberries are similar to red rspberries in growth habit.
Raspberries may also be classified as summerbearing or everbearing. Summerbearing cultivars produce one crop in the early summer, while everbearing cultivars can produce up to two crops a year, one crop being produced in the spring and the secon crop in the fall. Most everbearing raspberries are of the red or yellow type.
Popular Varieties
Summerbearing : Latham produces small red fruit with good color and fair flavor. Moderately productive. Very cold hardy. Mid-season fruit.
Everbearing : Heritage produces medium sized red fruit with good color and flavor, firmness, and freezing quality. High yielding. Late season fruit.
Fall Gold produces a medium sized yellow fruit. The soft fruits have an excellent flavor. Moderate yields. Early season fruiting.
Establishing the Planting
Raspberries will grow and produce on many different types of soil but will be most productive on sandy loam soils well supplied with organic matter and plant nutrients. The soil should be well drained and have a pH between 5.8 and 6.5.
Raspberries should be planted in an open site that receives at least 6 to 8 hours of sunlight. Avoid planting raspberries within 300 feet of any wild blackberry or wild raspberry plants and in areas where tomatoes, potatoes, or eggplants have been grown previously. Early spring planting is preferred over fall planting. Plant as soon as the soil can be properly prepared. The plants can be established either in hedgerows or using the hill system depending on the types of raspberries. Planting too closely results in undesirable competion, while planting too far apart wastes space.
Red or raspberries use either hedgerow or low trellis training system. Space plants 2 feet apart in the rows and 10 feet between rows.
Cultural Practices
The raspberry plants must be kept free of weeds, watered when necessary, fertilized, pruned regularly, kept free of insect and disease pests, and in some cases supported with a trellis.
Mechanical removal of weeds is highly recommended. A mulch of straw, sawdust, or other appropriate material can be very helpful for weed control, and soil moisture conservation in the raspberry plantings where the soil drains well. If soils are too heavy in texture and retain too much moisture, it may not be good to mulch raspberry plants. Mulching can worsen phytophthora root rot and/or verticillium wilt in raspberries planted in poorly drained soils.
Soil fertility should be maintained by two applications one pound of a 10-10-10 fertilizer or the equivalent per 100 feet of row at 10 and 40 days after planting. For the years after planting, raspberry plants need to be fertilized twice a year. The fertilizer should be broadcast in the row area once in the spring before growth begins in March, and one more time in May. Apply 2 to 3 pounds of a 10-10-10 fertilizer per 100 feet of row in each application.
Pruning
Raspberry canes are of two types, primocanes and floricanes. Primocanes are first year canes while floricanes are second-year fruiting canes.
Summer red raspberries should be pruned twice a year, first in the spring and immediately after harvest. The spring pruning, in late March or early April, consists of removing all weak canes and cutting back tall canes (over 5 feet) to 4.5 to 5 feet. The second pruning consists of the removal of canes that produced fruits, right after harvest.
Everbearing re raspberries such as "Heritage" raspberry can be pruned to produce fruit once a year or twice a year. If you follow the pruning methods used for summer red raspberries, "Heritage" raspberry will produce fruit once in spring and once in fall. Many home gardeners and commercial growers mow or cut all "Heritage" canes to the ground in early spring (March or April) for the sake of simplicity. "Heritage" raspberry pruned this way will produce only one crop starting in early to mid august.
Black and purple raspberries are pruned three times a year: in the spring, summer, and after fruiting. First pruning is done in spring when lateral branches are cut back to 8 to 10 inches in length in mid-March. Second pruning is called tipping or heading of new canes or primocanes. When grown without supports, summer tipping is done when black raspberry canes reach 24 inched in height and when purple types reach 30 inches. Tipping is done by removing the top 2 to 3 inches of new shoots as they develop. Third pruning involves the removal of canes that produced fruits, right after the harvest.
Supporting the Plants
A trellis can help make the crop easier to manage and keep the canes off the ground so that berries are cleaner and easier to pick. A trellis can be constructed with posts at 15 to 20 foot intervals with cross arms to support wires placed 24 to 28 inches apart. The wires should be about 36 inches high for red raspberries and 40 inches high for the black and purple types.