QWhat is the proper care of raspberry plants in spring and fall? What should be done about new plants that come out around them?
AIt is important to know when to prune raspberry canes to ensure good fruit production and control the plants' spread. Most raspberries produce fruit on canes that are in their second year of growth. The exceptions are fall-bearing or ever-bearing raspberries that can produce fruit in the fall on first-year canes. They also will produce fruit the next summer on two-year-old canes. For all types of raspberries, second-year canes die after producing fruit and should be pruned after harvest.
For summer-bearing raspberries such as Boyne, Nordic and Latham, first-year canes must be thinned. In a foot-wide row, you should leave only five or six main canes in each linear foot. Leave the thickest, healthiest canes and prune all others to the ground. If you didn't thin out the first-year canes last year, you also must thin out what are now the second-year (fruit-bearing) canes. If there is any winter tip damage on second-year canes, you can prune the tips in early spring; otherwise, second-year canes need no pruning.
Fall-bearing raspberries such as Heritage, Redwing, Autumn Bliss and Fallgold can be pruned two ways. The simplest method is to thin the first-year canes as described above, allow them to produce a fall crop of berries their first year, then prune all the canes to the ground after the harvest or in very early spring. If you leave the canes to produce a summer crop the next year, prune back the tips of these now second-year canes in the spring. You should cut them back to just below where fruit was produced the previous fall -- look for the remains of the fruiting clusters. Then cut the canes out after they produce the summer crop.
Red raspberries spread by sending out underground suckers that produce new canes, often many feet from the original plant. Allowing the plants to spread this way will result in a dense, tangled raspberry patch that will be difficult to move through to harvest berries. Ideally, raspberry rows should be limited to about a foot in width. The easiest way to limit the width of the row is to till the soil on the edge of the row in early spring, then once or twice more during the growing season to sever any suckers sneaking out underground. If you don't have a tiller, you can pull or cut back any suckers that come up outside the row. You will have to keep up with regrowth and new suckers through the season.
-- Nancy Rose is a research horticulturist at the Minnesota Landscape Arboretum. She spends her spare time gardening, inside or outside, depending on the weather. Please address gardening questions to her at the Minnesota Landscape Arboretum, P.O. Box 39, Chanhassen MN 55317. She will answer questions in this column only.