Blackberries, members of the genus Rubus, are classified as perennials, meaning the base structure persists and regenerates year after year. This persistent base supports numerous individual shoots, or canes, which are biennial, living for only two years before completing their life cycle. This combination allows the entire plant to maintain continuous productivity through the systematic turnover of its above-ground growth.
The Perennial Foundation
The survival and sustained production of the blackberry plant depend on its underground structures, which are the only truly perennial parts. At the soil line, a woody base known as the crown serves as the central point from which new canes emerge each spring. This crown is directly connected to an extensive, fibrous root system that spreads both vertically and horizontally, depending on soil type.
This root system functions primarily as a storage organ, accumulating and holding carbohydrates and nutrients produced by the canes throughout the growing season. The stored energy allows the entire plant to survive winter dormancy and fuels the rapid emergence of new canes and foliage the following spring. Without a healthy, well-developed perennial foundation, the plant would lack the resources necessary to initiate vigorous biennial cane growth and support a substantial fruit load.
The First Year: Primocane Development
The first stage of the cane’s biennial cycle begins with the emergence of a shoot known as the primocane, which rises from buds on the crown or the roots in spring. These canes focus all their energy on vegetative growth during their initial season, often growing rapidly to their full height by late summer. A primocane is characterized by its green color, vigorous stem growth, and the development of large, compound leaves that maximize photosynthesis.
This first-year growth is dedicated to structural establishment and energy accumulation. In floricane-fruiting varieties, the primocane will not produce flowers or fruit in this first season. As temperatures drop in the fall, the cane enters a dormant period, hardening its wood in preparation for the winter chill.
The Second Year: Floricane Fruiting and Decline
Upon breaking dormancy after the winter chill, the first-year primocane transitions into a floricane for its second and final year of life. The floricane does not increase in length but instead develops small side branches, known as fruiting laterals, from the buds along the main stem. These laterals are the structures that bear the flowers, which bloom in late spring and early summer.
Following successful pollination, the flowers develop into aggregate fruits composed of numerous small drupelets, which ripen from green to red, and finally to a dark purple or black color. The fruit can take between 35 to 60 days to develop from full bloom to a ripe, harvestable berry. After harvest, the floricane has fulfilled its purpose in the plant’s reproductive cycle and immediately begins to decline, senescing and dying back to the ground. This systematic death of the floricane clears space and directs the plant’s energy back into the perennial crown to support the growth of new primocanes for the subsequent year.
Natural Propagation Methods
Beyond the annual renewal of canes from the existing crown, the blackberry plant has evolved several effective strategies to propagate. One common method, particularly in erect varieties, is root suckering, where adventitious buds on the shallow, lateral roots develop into new shoots away from the parent plant. If these suckers are allowed to grow, they can form dense thickets and establish new colonies.
Trailing and semi-erect varieties often utilize a process called tip layering, or tip rooting. This occurs when the long, arching primocanes grow until their tips touch the soil, usually in late summer or early fall. The cane tip, once in contact with moist ground, naturally develops roots, forming a new plant that can be severed from the parent cane once established.
Finally, the fruit itself contains seeds. After being consumed by birds or mammals, these seeds can be dispersed over a wide area to germinate and initiate new plants, contributing to the plant’s long-term spread.