CORVALLIS, Ore. – It’s not too early in the year to begin doing a few simple chores to help raspberries and blackberries stay healthy and bear more fruit.
Bernadine Strik, a berry crops specialist with the Oregon State University Extension Service, suggests pruning raspberries in the late fall or winter. In summer-bearing raspberries, she says, remove dead fruiting canes and then cut the tops off and train new canes that will bear this coming summer.
Cut canes of primocane-fruiting raspberries in early March so they're mere stubs in the ground to get just a late summer crop on the tips of the new canes that will grow this spring. (Most types of raspberry canes grow and produce only leaves the first year, when they are called primocanes, and do not produce fruit until the following year, when they are called floricanes.)
If you want two crops, one in June and one in late summer, remove the dead tops on last year’s canes only. You’ll get a crop on the base of these canes in June and a late-summer crop on the tips of the new canes. No other pruning is necessary. Remove unwanted new canes or suckers that grow up between the rows once spring growth starts in both types of raspberries.
Prune and train most blackberries in either August or February. In trailing blackberries, such as Marion and Boysen, if you haven’t removed the dead fruiting canes and trained the new canes up the trellis yet, then do so in late February. Cut out last year’s dead fruiting canes and train the new canes after most of the risk of winter cold injury has passed, but before the buds start to swell, generally in mid- to late-February.
Blackberries and raspberries benefit from an application of horticultural oil and lime sulfur to combat pests and diseases when they are dormant.
Fertilize all cane berries in the spring. Fall-fruiting raspberries also need another shot of fertilizer at bloom in June.
Don’t forget to irrigate cane berries frequently throughout the fruiting season to insure good fruit size. Raspberries and blackberries need an inch to an inch and a half of water weekly. “If it doesn’t rain that much, you need to provide water,” Strik warned.
Pick fruit when fully ripe to ensure good quality. Over-ripe fruit on the canes promotes fruit rot.
Control weeds. They rob the fruiting canes of water and nutrients.
Be on the lookout for insect pests, especially leaf rollers and spotted wing drosophila. Control if necessary.
More information about growing and pruning cane berries is in two revised OSU Extension Service publications available for no charge online: “Growing Blackberries in Your Home Garden,” EC 1303, and “Growing Raspberries in your Home Garden,” EC 1306.