NC State Extension Publications

 

Raspberries can be a delightful and delicious addition to any home garden. The fruit is relatively easy to grow and needs few sprays for pest control. In general, most red raspberry varieties have difficulty in our hot, humid summer climate of the piedmont and coastal plain. And, in the foothills and mountains of western North Carolina, the raspberry plants are especially prone to winter freeze injury due to extremes in winter temperatures. However, with persistence and the right variety, a nice raspberry patch can be established in your backyard.

Variety Selection

Homeowners in the mountains have the greatest selection of varieties to choose from because the cooler summer temperatures are more favorable conditions for raspberries. A list of suggested varieties can be found in Table 1. Varieties listed as everbearing can produce two crops a season. There are several new varieties that are not listed in the table, but are worthy of trail especially in the mountains. A list of cultivars and nurseries can be found on the Blackberry and Raspberry portal.


Table 1. Raspberries for North Carolina.
Variety Season Area* Yield Size Flavor Remarks
Red Varieties
Autumn Bliss Everbearing M High Med-Large Very Good Some disease resistance
Cherokee Everbearing M High Large Good Tolerate fluctuating temperatures
Citadel Mid M High Medium Good Firm fruit
Dormanred Late CP High Large Fair Good for jams
Heritage Everbearing M, P High Medium Very Good Best everbearer
Nordic Everbearing M Medium-High Medium Good Good for freezing
Nova Early M Medium Medium Mild Dark red fruit
Reveille Early M Medium Large Very Good Soft fruit
Ruby Everbearing M Medium-High Very Large Good Requires good drainage
Southland Everbearing CP, P High Large Fair Some disease resistance
Summit Everbearing M Large Small-Medium Good Good for jams
Black Varieties
Allen Early to Mid M Medium Large Good Good adaptation
Bristol Mid M Medium Large Good Disease susceptible
Cumberland Mid M High Large Excellent Firm berry, hardy
* M = Mountains, P = Piedmont, CP= Coastal Plain

Soil Testing and Planting

It is best to test the soil four to six months before planting to allow adequate time to amend the soil based on test results. If the pH is too low, raise it to the level suggested by the soil test with dolomitic lime.

Keep plant roots moist until planting time by either heeling them into the ground temporarily or wrapping them in wet burlap. Do not leave the roots exposed to the drying effects of sun and air.

Prepare a planting hole large enough to allow the roots to spread out naturally. Do not prune the roots except to remove damaged ones. Set plants at the same depth they were planted in the nursery. The crown (the point where the stem and root merge) should be one inch below ground level; tissue culture plants at ground level.

After planting, tamp the soil firmly to remove air pockets around the roots. Water all new plantings well, immediately after planting.

Fertilization, Irrigation, Cultivation, and Mulching

Before planting, spade or till into the bed 1 pound of 10-10-10 fertilizer per 100 square feet of soil. Cultivate by hand and hoe between rows to a depth of 1 to 2 inches to prevent suckers from taking hold. Mulch with lawn clippings, pine straw, or pine bark.

Fertilize just after new growth starts in the spring (May) with a 10-10-10 commercial mix at a rate of 5 pounds per 100 feet of row. Repeat in July with another 2 to 3 pounds per 100 feet of row if vigor is low. In subsequent years, apply 8 pounds per 100 feet of row in March and repeat in May. Spread the fertilizer uniformly in a foot-wide band over the row, or sidedress with one-half the recommended amount of fertilizer on each side of the row.

Training and Pruning

Red raspberries tend to sucker and spread. As most of their fruit production is concentrated in the top one-third of new shoot growth, it is not advisable to prune them into a hedgerow as you would with blackberries. Instead, they should be trellised.

Thin fruiting canes in late winter or early spring before they start to grow. Remove all weak canes and thin the strong canes so they are 4-6 inches apart over the width of the row; narrow rows if necessary to 15-18 inches wide.

Remove fruiting canes at the end of harvest. Do it soon after harvest, to help control diseases. Make cuts close to the ground, also thin new shoots at this time, leaving 3 or 4 of the sturdiest canes per ft of row. If you use a single wire or one wire above the other type trellis, or stakes, tie the canes loosely to the support structure after summer pruning.

Dormanred red raspberries have to be trellised. The trailing primocanes should be tied to a stake or trellis after the second year canes have produced their crop, so the soil can be cultivated or mulched. Train Dormanred to a vertical trellis with a narrow wall of foliage. Space posts 20 feet apart and attach wires at a 5-foot height (Figure 1). This trellis system is suitable for most other red raspberry types as it will ease harvest and increase yields.

Heritage and other everbearing types may be annually pruned by simply mowing or cutting off all canes at or slightly below the soil surface late each fall. The following spring, new shoots (primocanes) will begin to grow. These canes will produce fruit on the tops in late summer through early fall. To delay the crop, the first flush of primocanes can be pruned to the ground when they reach a height of 12 inches or topped when they are approximately 30 inches.

For everbearing varieties, use a crossbar or horizontal trellising system. Two-ft crossarms are attached to the posts at a height of about 4 feet, and two wires are secured at the ends of the arms (Figure 2). The new canes will grow between and be supported by the wires with a minimum of tying. Remove first-season blooms to help plants get established and increase vegetative growth. Do not attempt to produce a crop the first season.

To get a second crop from everbearing varieties, do not prune the canes after they have fruited at their tips. They will produce a crop lower on these canes the following year, before the fruit from the newly emerged canes ripen. Once the canes have produced two crops prune them to the ground. Use a trellis system as described for Dormanred if you choose to allow these varieties to fruit twice a year.

Black raspberries do not need to be trellised at all. They are treated much the same as erect blackberries. Summer prune by pinching back in June when new shoots reach 18 to 24 inches. It is sometimes necessary to do this a number of times, as not all shoots will be tall enough for pinching on the same date. Terminal (end) growth stops when shoots are pinched back, but the three to five buds below the pinched area develop vigorous lateral growth. This allows the canes to become self-supporting.

After harvest, remove canes that have just fruited. In winter before growth starts, cut back side branches, leaving two to six buds (8 to 12 inches long) per cane. Remove very small canes (Figure 3).

Illustration of a red raspberry trellis

Figure 1. Red raspberry trellis for Dormanred variety. Wires are set at 5 feet above the ground. Treated posts are spaced 20 feet apart and set at least 24 inches into the ground.

Illustration of raspberries growing untrellised and on crossbar

Figure 2. Everbearing raspberries may be allowed to grow untrellised (A), but crossbar trellising (B) is recommended. Set crossbars to space the wires 18 to 24 inches apart and about 4 feet above the ground.

Illustration of black raspberry plant before and after dormancy

Figure 3. Black raspberry plant (A) before and (B) after dormant season pruning.

Harvesting

Harvest twice a week when fully ripe. Ripe berries will easily separate from the plant. Pick in the morning when the air is cool and berries are firm.

Weed Control, Cultivation, and Mulching

Keep plants in rows free of weeds by hand weeding, hoeing and cultivation or with a mulch. Raspberries may be grown under clean cultivation, sod or permanent mulch. The author prefers the mulch. The average homeowner has many organic residues around the home such as lawn clippings, leaves, or shredded vegetation. A raspberry planting is an ideal place to use these materials.

If you grow raspberries under clean cultivation, the area between rows is cultivated to a depth of 1 to 2 inches at intervals of 2 weeks from early spring to end of harvest. This controls weeds and red raspberry suckers in the row. If you use sod culture, mow the area between one row like a lawn throughout the summer to control growth of weeds, grasses and suckers. Where a permanent mulch is used, mow at timely intervals to control raspberry suckers between the rows.

Highest yields will likely be obtained with permanent mulch. Clean cultivation is next highest yield, and sod usually results in the lowest yield, but is easy to maintain for a homeowner.

Winter Protection

In colder regions of the state it is quite likely that the canes and buds of Dormanred will be winter injured if left up in the air in an exposed condition. In late fall untie canes from the trellis wires or stakes and lay them on the ground before the ground freezes to protect them from winter injury. Covering the canes with mulch should not be necessary

Watering

Plants need about 1 inch of water a week from bloom time to end of harvest. Plants should also be watered during prolonged dry periods after harvest as well. When watering, add enough water to wet the soil to a depth of 6 to 8 inches.

Use in the Landscape

Raspberries can make effective hedges or boundaries. Their canes are green red or purple and they have white flowers in the spring and summer. Most varieties sucker profusely and will need to be contained by cultivation or mowing.

Nutrition

Raspberries contain a significant level of vitamin C and are a rich source of soluble fiber. Raspberries contain ellagic acid which has been found to have anticarcinogen effects in laboratory animals.

Diseases and Insects

Many insects and diseases damage raspberries. You can avoid many pest problems by:

  1. Planting only quality nursery stock.
  2. Keeping plants well spaced with a narrow wall of foliage well exposed to light.
  3. Removing diseased or sick plants and all canes that have fruited, either burning them or removing them.
  4. Replanting with quality stock every 5 to 7 years.
  5. Removing wild brambles in vicinity of your garden.
  6. Keeping red and black raspberries separated by 700 feet.

Contact your Cooperative Extension center for current recommended spray programs or refer to the North Carolina Agricultural Chemicals Manual.

Author

Extension Specialist (Small Fruits)
Horticultural Science

Publication date: Dec. 31, 1996

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