The Chisago County Master Gardeners continue to take orders for bare root plants; although, we are running low on some popular varieties.
Every year I am asked why we don’t offer black raspberries, and every year I give the same answers. We order in large quantities to offer a good price to our customers and since we have very little demand for black raspberries, the cost would be much higher. I suggest they buy from a local nursery or garden center. Some seed catalogs will carry black raspberries, but make sure the zones in which they grow are in our area.
Gardeners have their favorites, whether it is apples, plums, sweet corn, raspberries, etc. Gardeners who raise black raspberries do so because they love them and they have success with them. I had black raspberries, and I agree they have a great taste, but for me it wasn’t worth the extra work.
If you are planning on starting a black raspberry patch, there are some things to be considered. Most varieties available are for zones 4-9, and since our area is still between 3 and 4, there may be some winterkill.
Black raspberries are more likely to get mosaic and other fungal diseases than red raspberries. This will reduce production and shorten the life span of the patch. The problem with diseases in most raspberries is that there isn’t much one can due except remove the patch and start a new one somewhere else.
The biggest problem I had with black raspberries was in the pruning. I would like to compare the rhizomes on weeds and raspberries. The rhizomes on quack grass and red raspberries spread from beneath the ground like strawberries and black raspberries. They also grow in hills and do not spread like reds. Those who do well raising black raspberries prune them three times each season.
The first pruning comes in early spring where the weak and broken canes are removed. The second pruning is when the plant is between 18 to 24 inches high. This is called tipping where the tip of each new shoot is pinched out. The third pruning is done right after harvest is complete. Remove at ground level and burn or destroy all canes that have borne fruit, as well as the weak spindly canes.
As I said earlier, those who know what they are doing and have patience do great with black raspberries.