Research conducted in the late 80's at HES Simcoe under the direction of Adam Dale indicated that biennial raspberry production was a viable technique suitable for Ontario growing conditions. In these studies the yields of the biennial treatments were equal to or greater than the annual system over a five year period. Until now there has not been a suitable technique to remove young primocanes so this system has not been widely promoted. Biennial raspberry production differs from annual production in that a portion of your planting is only allowed to fruit every second year. Some growers refer to this as alternate year mowing.
Biennial production takes alternate row mowing one step further.
The biennial system employs the same technique of mowing dormant canes after they finish fruiting. Additional management in the biennial system includes the maintenance of narrow rows during the vegetative year of growth and the use of primocane suppression during the fruiting year. A trellis or support mechanism for the cane is a necessity, not an option. For many years researchers and growers have know that for optimum yield raspberries must be managed with a cane density of approximately 15 canes per metre of row. The reasoning behind this practice is based on the fact that raspberry plants can only intercept so much light.