Healthy blueberry bushes will grow for 10 years or more, and all that continuous growth can mean your bushes get a little out of control. A pruned and well-managed bush will produce more fruit for you and is usually more compact for easier harvesting.
It can be a little nerve-wracking to take a pair of shears to your blueberry bushes, but you are really improving the health of the plants as long as you are careful when you prune.
First of all, it is important to do your pruning at the right time of year. Plants should be still dormant, but not about to enter the harsher winter weather (particularly in northern areas). Late winter or very early spring is the right season for pruning.
You will also want to wait until the plant is thriving and well-established before doing any pruning. It should be at least 3 years old, and if you were planting 3-year old seedlings in the first place then wait an additional year. Even at the age of 4 or 5 years, most bushes will only need a minimal amount of tidying up so you may want to wait a few more years.
The easiest parts to cut away are the dead or broken branches. They can harbor insects or disease, so you should remove them straight away.
Besides that, you need to examine the bush and see which branches are getting older and no longer producing any new berries. Blueberries produce fruit on new growth, so older branches are using up resources but not giving you any berries. Any branches that are about 5 years old can be taken out. These will be thicker and woodier than the new growth. You should always leave at least 6 to 8 strong branches so that the bush can continue growing properly.
Any branches that are low-growing out from the base of the plant can also be removed. Any small or spindly branches within the bush can also be cut away, to help bring more light into the center of the bush.