Traditional floricane or summer-bearing raspberries produce fruit on wood that grew the previous year. The plants flower in the spring on 2-year-old wood, berries mature in June, then new canes grow for the rest of the summer. Remove canes at the ground after they produce fruit so that they do not form an unproductive, impenetrable thicket. In areas with cold winters young canes often suffer freeze damage during the winter.
Canes on everbearing, or primocane, varieties start growing in early spring and produce a crop of raspberries on new wood at the end of the summer. These same canes will produce a smaller crop the next June if they remain on the plant. Generally, the canes are mowed off after the fruit is harvested because this eliminates freeze damage and allows all of the plant's energy to go into producing a large fall crop.
Black and purple raspberries produce fruit on branches that grow out of the sides of old canes. These side branches produce fruit in their second year. In summer remove fruit-producing canes after harvesting the fruit and cut off new canes 3 to 4 feet above the ground to encourage them to form branches. In late winter, thin the canes, leaving four to six of the strongest canes per foot. Cut back the side branches. Black and purple raspberries are generally less cold hardy than red raspberries.
Space red and yellow raspberries 2 to 3 feet apart in the row. Summer-bearing varieties are often trellised. Everbearing varieties grown in a wide hedgerow will support each other, or you can provide a temporary trellis that can be removed for mowing. Black and purple varieties should be spaced 3 to 4 feet apart to allow room for the side branches. Trellis black raspberries on a low trellis. Purple varieties are sturdier and will support themselves.