Before you start, know your primocanes from your floricanes
Red raspberry plants, after pruning.
Photo/Illustration: Ann Stratton
To prune any plant properly, you need to understand its growth cycle. In the case of red raspberry, the roots and crown are perennial but the canes are biennial (they live for only two years). The first year, they emerge as green primocanes and form fruiting buds. If you have a summer-bearing variety, these buds won’t flower until the following year. If you have an everbearing variety, the buds at the tips of your primocanes will give you a small fall crop, and the buds lower on the canes will remain dormant until next season. As winter nears, primocanes drop their leaves and develop a thin brown bark.
In their second year, the canes are called floricanes. The previous year’s buds grow into fruiting branches and bear a summer crop. As their berries ripen, floricanes begin to senesce. Their leaves turn red or yellow, and they die as winter approaches. A big part of pruning a red raspberry is getting rid of these spent floricanes. To keep your plants from getting unruly during the growing season, cut back any new canes that emerge outside the desired row width of 2 feet; however, don’t touch the new green shoots growing within the prescribed row width. It’s not until late winter that you prune the entire plant.
In fall, resist the temptation to cut out the dying floricanes that fruited that summer. Research conducted at Cornell University indicates that these canes send carbohydrates to the crown and roots well into early winter, helping the plant survive dormancy.