Raspberries for the Home Garden

Quick Facts...

• Of all bramble fruits, only red and yellow raspberries are recommended for general cultivation in Colorado.
• Red raspberries grow well in most garden soils that are amply supplied with organic matter and adequately drained.
• Plant only true-to-name, disease-free stock.
• Twenty-five feet of row should produce 15 to 20 pounds of raspberries per year.
• Relocate a raspberry planting every eight to 10 years with new, clean stock.

Selected varieties of red and yellow raspberries (Rubus idaeus) may be successfully grown in Colorado at elevations up to 8,500 feet. Colorado's climate is not especially favorable for bramble fruit production, and only red and yellow raspberries are recommended. Black and purple raspberries, as well as blackberries, boysenberries, loganberries and dewberries, require special winter protection and are not recommended for Colorado.

Types

There are two types of red raspberries: summer-bearing and fall-bearing. The standard varieties are biennial summer-bearers that produce canes the first season and bear fruit on short lateral branches of these canes the following summer. Fall-bearing raspberries also produce canes (suckers) from the roots but require no dormant period for fruiting. These canes bear fruit in August and September of the first season. These canes may overwinter and produce a light summer crop, but this is at the expense of a reduced fall crop.

Varieties

Recommended summer-bearing red raspberries include Latham, Boyne, Newburgh, Canby and Titan. Recommended fall-bearing red raspberries include Redwing, August Red, Heritage, Fall Red, Fall Gold (yellow-fruited) and September. Pathfinder and Trailblazer are two hardy varieties but are not yet widely available.

Based on Colorado State University tests, fall-bearing types, particularly Heritage and Redwing, seem best adapted to the Front Range. Both fall-bearing and summer-bearing varieties do well on the Western Slope, but fall-bearing varieties are easier to manage.

Soil Preparation

Red raspberries grow in most garden soils if they have ample organic matter and adequate drainage. For summer-bearing raspberries in good garden soil, apply only a maintenance amount of fertilizer: 4 pounds of ammonium sulfate and 2 pounds of treble superphosphate per 1,000 square feet. However, if the soil has not produced a good garden, have it tested before planting. If soil is not tested, apply 8 pounds of ammonium sulfate and 4 pounds of treble superphosphate, 1 pound of zinc sulfate, 1 pound of iron chelate and 10 bushels of organic matter per 1,000 square feet. Work these in before planting. For fall-bearers, increase the amounts of fertilizer by 50 percent.

Maintain soil fertility with a spring application of 4 pounds of ammonium sulfate and 2 pounds of treble super phosphate per 1,000 square feet. Scatter among the canes and cultivate into the soil.

Apply enough water to maintain a moderate moisture level in the root zone. Withhold water after the first frost to help harden off the plants. A late November watering reduces winter drying.

Planting Raspberries

Red raspberries are commercially propagated by rooted suckers. Plant them in the spring, 2 to 3 feet apart in rows 5 to 10 feet apart, depending on the width of the cultivating equipment. After planting, cut the tops to within 4 to 6 inches of the ground. Be careful planting bare-rooted stock because it is somewhat difficult to establish. Soak bare-root plants in a bucket of water five hours to overnight to help them get established.

After one or two years, suckers fill in the row to form a hedge of canes. Thin the suckers to 6 inches. The hedge row should not be more than 2 feet wide at ground level.

Figure 1: Raspberry trellis with dormant canes secured to wires.

Trellising

Fall-bearing raspberries seldom require trellising; however, summer-bearing varieties may require some kind of support. Stretch a wire on either side of the hedge row, 3 feet above the ground. This wire confines the canes to the hedge row. To make them stand erect, you may have to tie the canes to the wire with soft twine. See Figure 1.

Pruning

Remove the canes of summer-bearing varieties by cutting them off at the ground after they bear fruit. Dispose of these canes -- they often harbor Insects and disease. In the spring, remove the dead, weak and small canes, leaving canes at least 6 inches apart in the hedge row. Remove winter-killed tips of the remaining canes. Mow the canes of fall-bearing varieties to ground level after the fall harvest.

Winter Protection

To obtain a crop of summer-bearing raspberries in most areas of Colorado, protect the canes during the winter. Sometime after November 1, lay the canes down in one direction and hold them in place with a shovelful of soil on their tips. Plow or shovel a shallow furrow along each row and roll the soil over the canes. In early April, use a pitchfork to lift the canes out of the soil. Put the soil used to cover the canes back into the furrow.

The advantage of fall-bearing varieties is that winter covering is not needed -- the canes are mowed off after harvest. However, if a summer crop is desired from these canes, they must be protected as described for summer-bearing raspberries.

Yield

By the third year, a 25-foot hedge row of red raspberries should yield 15 to 20 pounds of fruit per year under optimum conditions. After this, productivity will decline. After eight to 10 years, relocate the bed, starting with new stock.

Disease and Insects

Raspberries are affected by a wide range of diseases and Insects, as are most cultivated plants. You can avoid most of these problems for several years by purchasing only quality, true-to-name, disease-free raspberry varieties.

It is almost inevitable, however, that during hot, dry weather, raspberries along the Front Range will be infested with spider mites. The mites themselves are not obvious, but their presence is indicated by tiny yellow spots on the leaves, which eventually turn brown. Spray the mites, which feed on the underside of the leaves, with one diazinon or malathion according to label directions. Observe the required waiting period between spraying and harvesting, as stated on the label.

Raspberry cane borers have been reported in Colorado. Symptoms of this serious pest include a sudden wilting and drooping of tops of canes. The white larvae of the borer, if left uncontrolled, burrow down through the cane and kill it. Remove infected canes at the first sign of an infestation. To control this insect, apply Sevin (carbaryl) or another insecticide before blossoms open. Follow directions on the label when applying any insecticide.

References

• Lawrence, F. T. Growing Raspberries. Farmer's Bulletin 2165, U.S. Government Printing Office, Washington, D.C. 20402. 1979.
• Shoemaker, T.S. Small Fruit Culture, 5th Edition. AVI Pub. Co. Inc. Westport, Conn. 1977.

Go to top of this page.