AMES, Iowa — Pruning raspberries in spring produces higher yields, by increasing berry size, and helps control disease. Pruning procedures are based on the growth and fruiting characteristics of the plants, according to horticulturists with Iowa State University Extension and Outreach. To have additional plant and garden questions answered, contact the ISU Hortline at 515-294-3108 or email@example.com.
Summer-bearing red raspberry varieties include ‘Latham,’ ‘Boyne,’ ‘Killarney,’ and ‘Newburgh.’ All summer-bearing red raspberries should be pruned in the same manner.
In March or early April, remove all weak, diseased and damaged canes at ground level. Leave the most vigorous canes, those approximately 1/4 inch in diameter when measured 30 inches from the ground. After thinning, remaining canes should be spaced about 6 inches apart.
Also, prune out the tips of the canes that have died due to winter injury. Cut back to live tissue. If the canes have suffered little winter dieback, remove the top one-fourth of the canes. Cane-tip removal or “heading-back” prevents the canes from becoming top heavy and bending under the weight of the crop.
To obtain maximum yields, red raspberries should be confined to a 1- to 2-foot-wide hedgerow. Shoots growing beyond the 1- to 2-foot-wide hedgerow should be dug up and destroyed using a rototiller or spade.
Popular fall-bearing red raspberry varieties include ‘Heritage,’ ‘Redwing,’ ‘Caroline’ and ‘Autumn Bliss.’ Fall-bearing red raspberries naturally produce two crops. One crop is produced in summer on the previous year’s growth. A second crop is produced in late summer or early fall at the tips of the current year’s growth. Fall-bearing red raspberries can be pruned two different ways in March or early April.
One pruning option is to prune out all weak, diseased and damaged canes at ground level. Leave the largest, most vigorous canes. Cut back the tips of the canes that remain. Remove approximately the upper one-third of the canes. This option provides two crops during the year.
The second option is to prune all canes back to the ground in late winter/early spring. This pruning option produces a single crop in late summer or early fall. (The summer crop is eliminated.) While only one crop is produced, total crop yield is actually larger than the two crop system.
Red raspberries sucker profusely from their roots. To prevent the planting from becoming a wide, unmanageable thicket, red raspberries should be confined to a 1- to 2-foot-wide hedgerow. Shoots growing beyond the 1- to 2-foot-wide hedgerow should be destroyed using a rototiller or spade.
In March or early April, remove all small, weak canes, leaving only four or five of the largest, most vigorous canes per clump or plant. Cut back the lateral (side) branches to 12 inches in length.
In March or early April, remove all small, weak canes, leaving only four or five of the largest, most vigorous canes per clump or plant. Cut back the lateral (side) branches to 18 inches in length.