Raspberries grow on perennial shrubs classified under the Rubus genus, a diverse group within the rose family, Rosaceae. These plants are often called cane fruits because their specialized stems, called canes, emerge from the ground to produce the fruit. Although the overall raspberry plant is perennial, the individual canes follow a two-year life cycle before dying back. Understanding this dual-lifecycle structure is necessary for successful cultivation.
The Structure of the Raspberry Plant
The raspberry plant consists of two distinct parts: the perennial root system and the biennial canes. The underground portion, including the roots and the crown, is long-lived, often remaining productive for 10 to 15 years or more. The perennial crown is the base from which all new growth emerges each season, ensuring the plant’s long-term survival.
The visible, above-ground structures are the stems, known as canes, which are woody and typically covered in small prickles. These canes grow vigorously, reaching heights of 5 to 8 feet depending on the variety and growing conditions. The canes are semi-woody stems that complete their life cycle in two years.
Understanding the Cane Life Cycle
The two-year life of a raspberry cane is divided into two stages: the primocane and the floricane. A primocane is the first-year growth, focused on vegetative development, meaning its primary purpose is to grow tall and accumulate energy. Primocanes are generally green, vigorous, and develop leaves but typically do not produce fruit during this initial season.
After a primocane overwinters, it transitions into its second-year stage, becoming a floricane. Floricanes produce flowers and ultimately bear the fruit, usually in the early to mid-summer. Once the floricane has completed its fruiting cycle, it naturally dies back to the ground. This continuous cycle ensures an established raspberry patch always contains both first-year primocanes and second-year floricanes.
This life cycle classifies raspberry varieties into two main types: summer-bearing and everbearing. Summer-bearing varieties are floricane-fruiting, producing a single, concentrated crop on the second-year canes. Everbearing (or fall-bearing) varieties are primocane-fruiting, producing a crop on the tips of the first-year canes in the late summer or fall. These canes can then produce a second, smaller crop lower down the stem the following summer before dying.
Growth Habit and Necessary Support
Raspberry plants naturally tend to spread and form a thicket due to their vigorous growth habit. Red and yellow raspberries in particular spread outward by producing new canes, called suckers, that emerge from buds along the roots some distance from the parent plant. This allows the plant to form a dense row or “hedgerow” if not managed.
Because raspberry canes are slender and grow tall, they are not structurally strong enough to support a heavy fruit load, especially when wet. Supporting the canes is a necessary practice for most varieties, particularly the taller, summer-fruiting types. Common support methods include using a trellis system, which involves running horizontal wires between sturdy end-posts.
Canes are tied loosely to these wires or placed between parallel wires to keep them upright and organized. Trellising prevents the canes from falling over, which helps increase air circulation to reduce disease risk and makes harvesting significantly easier. Proper support ensures the plant directs its energy toward fruit production rather than growing into an impenetrable thicket.