For backyard blueberry growers, winter means it’s time to break out the pruning shears and folding saw. Pruning blueberries is a task best performed yearly, when the plants are dormant. Closely tied to crop production, plant health, and fruit quality, pruning too aggressively – or not aggressively enough – impacts your blueberry’s performance.
Reasons for pruning blueberries
Pruning blueberries is an essential winter chore for several reasons.
- Proper pruning maintains an open growth habit, which improves air circulation, opens the center of the plant to sunlight, and reduces disease.
- Annual pruning maintains productivity by encouraging the growth of new fruit-producing stems.
- Pruning removes dead or damaged branches.
- Pruning increases fruit quality because the shrub is able to put more energy into producing the fruit, not more leaves.
The goal of good blueberry pruning is to remove enough old growth to encourage the production of new. And to do so without negatively impacting the berry production for the coming season.
When to prune blueberries
As with most other fruit-producing trees and shrubs, blueberry pruning takes place in mid to late winter. It’s easy to see the structure of the plant more clearly then and discern which branches are to be removed. In winter, the old branches look very different from the new in color and texture (see photos below). Plus, dormant-season pruning causes the plant less stress. The bush is not in an active state of growth, and no carbohydrate-producing foliage is being removed.
The regions where blueberries grow well are those with a dormant season of December through early March. Blueberry shrubs are extremely hardy. Some varieties survive down to -35 degrees F. In fact, blueberries need a set number of hours below 45 degrees F (called chill hours) in order for their flower buds to open and produce berries. Without ample cold weather, blueberries do not produce fruit.
Each blueberry type and variety has a slightly different number of required chill hours. Low-chill blueberry varieties require 200-800 chill hours and are best for southern regions. High-chill selections need 800-1000 hours and are ideal for the north. When buying blueberry plants, select a variety that’s suitable to your region.
Pruning blueberries can take place as early as late December. However, I recommend waiting until late February or very early March for this task. You’ll be able to prune off any stems that suffered winter injury or breakage due to heavy snows. Plus, the chance of winter injury has largely passed.
The different types of blueberries and their pruning needs
There are many different types of blueberries, including high-bush, low-bush, rabbit-eye, and lots of assorted hybrids. In the north, ‘half-high’ varieties are among the most popular. They are the result of the hybridization of high-bush and low-bush types, and are a great fit for most backyards. They grow 3 to 4 feet in both height and girth, and bear plenty of fruits. Southern gardeners should opt for ‘Rabbit eye’ blueberries as they are more heat tolerant and need fewer chill hours.
Don’t forget that you’ll need at least two different varieties of blueberries to get fruit. Most varieties require a cross-pollination partner. (Those listed in the article linked here, however, are self fertile.) Blueberries are primarily pollinated by our native bumblebees because the vibrations these large bees generate are required for loosening and transferring the pollen in the bell-shaped flowers of blueberries.
Regardless of which type of blueberries you grow, the task of pruning blueberries is the same.
Tips for pruning blueberries
How to prune blueberries depends on whether the plant is new and relatively young or old and overgrown. Below you’ll find step-by-step blueberry pruning instructions for both situations. However, I’d like to share a few key points about pruning blueberries first.
- Never shear back blueberries and turn them into the shape of a meatball. Their fruiting buds are located in the outermost 2-3 inches of stem growth. Shearing back the plants removes all the flower buds.
- If you don’t properly prune your blueberry bushes, the existing branches will age, but new, fruit-producing branches will not be formed. Older, unpruned blueberry bushes tend to produce more leaves than berries, and any berries that are produced are small and produced only on the outermost stems.
- Be sure to use clean, sharp pruning equipment. To avoid the spread of disease, disinfect all pruning equipment before moving from one bush to another. I use a special spray pruning disinfectant that doesn’t gum up or rust your equipment, but you can also dip your tools in a 10% bleach solution or use Lysol spray.
- Blueberries produce their flowers on old wood, meaning that the buds for each year’s berry crop are formed during the summer and autumn of the previous season. Protect your blueberry bushes from deer in the winter or they may strip all the buds off the stems.
Pruning blueberries step-by-step
Stand back and evaluate your blueberry bushes one at a time. Begin by cutting off any dead or damaged branches. Cut these stems off all the way back to where they join a thicker branch. Do not leave a stump behind as it serves as an entryway for disease. If the entire branch is dead, cut if off back to the ground.
After any damaged stems are removed, cut out any crossed branches, particularly those that rub against each other. After pruning is complete, you want an open structure with no crossed branches. Cut crossed branches off all the way down to the base of the plant.
For young blueberry bushes or those that have been properly pruned in the past: Cut one-third of the remaining branches all the way down to the ground, choosing the oldest and thickest ones for removal. This encourages new, productive canes to emerge from the roots. Yes, that means cut 1 out of every 3 branches clear to the ground to stimulate new stems to emerge from the roots. Do this every winter and you’ll always have excellent blueberry production.
For mature blueberry plants that are unpruned and overgrown: Perform a careful renewal pruning to encourage new stem production by cutting half of branches back all the way down to the ground. Always cut off the oldest, thickest ones. This forces new canes to grow from the roots. When a branch is seven or eight years old, production is greatly reduced. If you don’t remove old branches, the plant fails to generate new, more productive stems.
Over the following two to three years, remove the remainder of the oldest branches a few at a time until only newly produced ones remain. The plant continues to produce a moderate crop while the bush is being slowly rejuvenated. Heavily pruned, overgrown bushes take a few years to rebound, but your efforts pay off in the long run with many years of terrific production after the plants are regularly pruned.
Pruning blueberries is emotional
There’s no doubt that pruning blueberries is an emotionally taxing job. It’s particularly difficult to see all the buds being cutting off. But, don’t feel guilty about removing branches with potential fruit. If your goal is to increase your blueberry’s long-term productivity and grow larger fruits, then pruning properly is a must. Just have some wine on-hand for after the job is complete!
Blueberry pruning is an annual chore. Mark your calendar so you don’t forget!
When spring arrives, here’s how to fertilize pruned blueberry bushes to adjust the soil pH or add an acid-specific organic granular fertilizer, such as HollyTone. Then, mulch the bushes with one to two inches of pine straw, shredded hardwood bark, or shredded leaves. Do not over-mulch. Blueberries have shallow, fibrous root systems that resent thick layers of mulch.
By following these blueberry pruning instructions, you’ll have productive plants for years to come!
For more on growing backyard fruit, check out these articles:
- Organic apple growing using fruit bagging
- Berries in containers: How to grow a small-space fruit garden
- Growing kiwi fruit: It’s easier than you think
- How to grow citrus in pots using 8 simple steps
- 5 mini melons for small gardens and containers
Do you grow blueberries? Which varieties are your favorites?