How and When To Prune Blueberry Bushes
Pruning is necessary to maintain the health of your blueberry bushes. However, you must be careful as pruning can directly effect the fruit production of your plant. Pruning is best done when the bush is dormant, either in the late fall or the early spring. Spring is often the preferred time because you will be able to see which (if any) branches were damaged through the winter and need to be trimmed.
Once you have removed the damaged branches, you will want to remove some of the lower growing branches. You can controll the height by trimming some of the more vigorous upright shoots. You will also want to thin out some of the older weaker canes. After these have been trimmed, you can select some of the smaller, thinner (or spindly) branches.
Keep in mind that berries are grown on canes that are at least 1 year old, so any branches you trim will now produce berries. The more severe the pruning, the less berries you will be able to harvest and the growing season will be shorter. At the same time, you don't want to skip pruning. Although mild pruning will lead to a longer harvest and more berries, they will be smaller.
If damaged and weak branches go unattended, the quality of the berry will deminish and the bush will be more susceptible to issues like insects and disease that can limit your crop.