Raspberries have a unique life cycle that often confuses new gardeners because the plant itself is a perennial, but its above-ground growth is biennial. A perennial plant’s roots and crown live for more than two years, often indefinitely, establishing a permanent patch. However, the individual raspberry stems, known as canes, only live for two growing seasons before dying back completely.
Perennial Roots and Biennial Canes
The root system and crown of the raspberry plant remain alive year after year, classifying the plant as a perennial. This underground structure continuously sends up new canes, ensuring the patch remains vigorous and productive. The individual canes, however, follow a strict two-year life cycle, making them biennial.
In the first year, a cane emerges from the ground and is called a primocane. This cane is green, thick, and focused on vegetative growth, storing energy and developing strong buds. Primocanes generally do not produce the main crop of fruit, though some varieties are exceptions.
After surviving the winter, the primocane transitions into its second year and is renamed a floricane. These floricanes are the structures that produce the majority of the raspberry crop, developing fruiting laterals that flower and set fruit. Once the floricane has finished fruiting, it dies back completely, having completed its two-year cycle.
The Importance of Pruning for Continued Growth
Pruning is a biological necessity for maximizing fruit production and maintaining the health of the raspberry patch. Since floricanes die immediately after bearing fruit, they will never produce berries again. Leaving these spent canes in place creates a dense, congested environment that inhibits new growth.
Removing the old, spent floricanes improves air circulation within the patch, which helps prevent fungal diseases. The dead canes are typically gray, woody, or brittle, making them easy to distinguish from the new, vibrant green primocanes. Removing these spent canes also directs the plant’s energy toward the new primocanes, which produce fruit the following year.
Pruning stimulates the growth of new primocanes from the perennial crown, ensuring a continuous cycle of renewal. By cutting the floricanes down to ground level after harvest, the grower is essentially clearing the space for the next generation of canes to grow strong and healthy. This annual removal of dead wood is the simplest way to manage the biennial nature of the canes within the perennial system.
Managing Summer-Bearing and Fall-Bearing Varieties
The timing and method of pruning depend on whether the raspberry is a summer-bearing or a fall-bearing variety. Summer-bearing raspberries, also known as floricane-fruiting varieties, produce their main crop exclusively on second-year wood (floricane). For these types, all spent floricanes should be cut down to the ground immediately after the summer harvest, leaving the new primocanes to overwinter and fruit the next year.
Fall-bearing raspberries, also called primocane-fruiting or everbearing varieties, fruit on both first-year and second-year wood. They produce a crop on the tips of the current year’s primocanes in the late summer or fall. If these canes are left over winter, the lower portion of the cane will produce a second, earlier crop the following summer, after which the entire cane dies.
Single-Crop Method
The single-crop method is the simplest management approach. It involves cutting all canes, both primocanes and floricanes, down to ground level during the late winter or early spring dormancy period. This sacrifices the small summer crop but results in one larger, concentrated harvest in the fall.
Double-Crop Method
Alternatively, the double-crop method involves managing the fall-bearers like summer-bearers. This means removing only the spent floricanes after the summer crop. Growers also prune the tips of the primocanes after the fall crop, which provides two smaller harvests per year.