How Fast Do Raspberry Plants Multiply?

Raspberry plants (Rubus spp.) are perennial bushes that produce berries on branches called canes. One full year after planting a new crop, each original cane will have a handful of new canes popping up nearby. New raspberry canes form each year starting in the spring. Primocane types of raspberries bear fruit the first year, while floricanes bear fruit in the second year, but they each produce new raspberry canes every year. Raspberries are self-fruiting and therefore only one cultivar is needed for reproduction. Raspberry plants typically produce fruit for more than 15 years.

Primocane-type cultivars produce flowers and fruit in the first year, and an additional fruit crop the second year. These types are also called fall-bearing or ever-bearing because they produce a fruit crop in both early and late summer. Primocanes fruit on the top portion of each cane during the first year. Following the harvest, the top portion dies, but the same cane bears fruit on the lower portion the next year. The dead tops of primocanes should be pruned following harvest in late summer.

Floricane-type cultivars produce only leaves and flowers during the first year, and produce berries during the second year. These varieties are typically called summer-bearing because they produce their fruit crop during June and July only. Canes die during their second year, following berry production. New plantings of floricane types will produce no berries during the first year planted, a small crop during the second, and a fully mature crop during the third year.

Raspberry plants thrive in cool weather climates and can be grown in U.S. Department of Agriculture plant hardiness zones 4 through 9. They grow best in full sun but are tolerant of shade, and prefer a slightly acidic soil pH of between 5.5 and 6.5. Good drainage is essential for a healthy crop of raspberries and waterlogged or heavy clay soils will promote root rot or other moisture-related diseases. Raised beds are the best way to maintain well-draining soil full of organic matter.

Each year, the roots and crown of a plant produce numerous new canes, or suckers. For healthy expansion, choose either a hill or hedgerow system to control density. Hedgerows are space saving and good for cultivars that produce abundant suckers. Hill systems are best for black and purple types of raspberries. Plant new rows with canes spaced 2 feet apart. To use the hill system, allow new canes to grow only within 1 foot of the original, and prune all others in between. For hedgerow systems, allow canes to grow at all points between the original canes, but prune to maintain a row width of 12 inches. Canes from mature plants -- at least 3 years old -- can be dug up and relocated in the garden.