How to: Prune Highbush Blueberries

by: Greg Welfing

How and when to prune blueberry bushes are very common questions that come up during the winter months. The answer to the ‘when’ question is the easiest. The best time to prune blueberries is when the plants are fully dormant. In the Fraser Valley this is normally from November through February. Pruning the plants at this time causes the least amount of stress to the plants and should be the only time large scale pruning is done. Pruning right after harvest while the plants are still active can lead to increased winter damage and loss of productivity. Pruning is required to maintain the vigour and productivity of the bush as well as to ensure good fruit size and quality for the following year. If done properly, the practice of pruning can also be a disease management tool and harvest aid.  The ‘how’ to prune blueberries question is a little more difficult to answer, but here are a few guidelines that can assist you while doing your annual pruning:

1. Observe the bush before starting pruning. Visualize how the plant should look after pruning. A mature bush should have 8-10 canes of various ages (1-5 years) left after pruning.
2. Remove any dead or diseased canes. Cankers and Bacterial Blight are two diseases that can be minimized with good pruning practices. 
3. Young wood (1-2 years old) is the most productive. Prune out any canes that are older than 6 years old. These will be the largest and thickest canes with grey wood and peeling bark. 
4. Prune the bush for upright growth. Remove canes that grow laterally out into the aisle.  This allows easier harvesting by machines. 
5. Remove any twiggy growth and excessive growth in the center of the bush. Having a bush that is open in the center allows for better light penetration as well as better air movement. This allows for better spray penetration as well as reduced fungal disease pressure. Having fruit on the outside of the bush also makes for easier hand harvesting.
6. Remove any short stubby growth at the base of the plant. A narrow plant base allows for a narrower gap between catch plates and less fruit loss while machine harvesting.