Sunday, March 18, 2012

Pruning raspberries

This source has a couple of approaches for pruning raspberries.

First, some background:

Raspberries are unique because their roots and crowns are perennial, while their stems or canes are biennial. A raspberry plant may survive and produce fruit for many years. However, individual canes live only two years and then die.  
During the first growing season, the shoots of purple, black, and summer-bearing red raspberries are strictly vegetative (non-fruiting). The following year, these same canes flower, produce fruit, and then die.  
Fall-bearing red raspberries naturally produce two crops. The first crop is produced in late summer or early fall at the tips of the current season’s growth. The following year, a summer crop is produced on the lower portions of these same canes. After the second crop, the canes die. 
Red raspberries produce new canes from buds located at the base of the previous season’s growth and on their roots. Because red raspberries sucker freely, they need to be confined to a 1- to 2-foot-wide hedgerow.  
 Here are the overall instructions:
In March or early April, remove all weak, diseased, and damaged canes at ground level. Leave the most vigorous canes, those approximately ¼ inch in diameter when measured 30 inches from the ground.  
When finished, remaining canes should be spaced about 6 inches apart. Also, prune out the tips of the canes that have died due to winter injury. Cut back to live tissue. Maintain plants in a 1- to 2-foot-wide hedgerow using a rototiller or spade.  
After the last harvest of summer, prune off the old fruiting canes at the soil surface. Remove the pruned material from the garden and destroy it.
However, there are two sub-approaches: one for having two yields annually, and one for one (bigger) yield:

How to prune fall-bearing red raspberries for two crops (basically the same as the above):
In March or early April, remove all weak, diseased, and damaged canes leaving only the most vigorous canes. Also prune out the tips of the canes. The summer crop will be produced on the lateral (side) shoots of the remaining portions of the canes. Maintain the plants in a 1- to 2-foot-wide hedgerow.  
After the summer crop has been harvested, remove the old fruiting canes and destroy them. 

How to prune fall-bearing red raspberries for one crop 
(Total crop yield is typically larger using the one-crop system instead of the two-crop system.) In March or early April, prune all canes back to ground level. This eliminates the summer crop, but the fall crop matures one to two weeks earlier. Maintain the plants in a 1- to 2-foot-wide hedgerow. No summer pruning is necessary.
I'm going to try both approaches; I'll try the "razed earth" approach for the single crop on the South side, and the selective double crop on the North. We'll see ...

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