(News article for June 24, 2019)
As many of you are aware, it’s customary to prune azaleas, if needed, soon after flowering. Azaleas bloom on growth produced in the previous season, so this gives the plant time to put out new growth and for flower buds to form on the new growth, so that the plant will bloom the following year.
A similar approach can be taken with blueberries. Some varieties are finished or almost finished fruiting by now. Our growing season is long enough that we can prune blueberries soon after harvest (by the end of July, as a rule of thumb), and the plants will have time to set flower buds (from which fruit develop) for the next year on shoots that grow after pruning.
While it’s not absolutely necessary to prune blueberry plants every year, reducing their height can make them easier to pick. The amount of new growth that the plants put out after they’re pruned will depend to some extent on their vigor and the fertility of the soil, but as a general guideline, cut them to about one foot lower than the maximum height at which you want to pick berries next year. So, if you don’t want to reach to more than six feet to pick berries, prune them back to five feet tall. If you’re fine with pulling shoots down to reach berries at seven feet from the ground, you can cut them back to six feet.
An added benefit of pruning blueberry plants after harvest is that flower buds on vigorous shoots put out in the summer tend to break later, during the following year, than flower buds on less vigorous growth produced earlier in the season. This means that in years in which we have a late freeze – as we did this year – it’s less likely that flowers on these shoots will be injured by low temperatures.
Besides reducing plant height after harvest for ease of picking, the other major step to pruning mature rabbiteye blueberry plants is to remove one to three of the oldest canes. This can be done after harvest, as well, or during the winter, when plants are dormant. Look for canes that are roughly one inch or more in diameter at the base and cut them close to the ground. The amount of wood cut out each year should be roughly 10 to 20% of the total wood present.
Removing some of the oldest canes each year allows more light into the bush so that fruit isn’t just produced on the outside of the canopy. It also encourages well-established blueberry plants to put out new canes from the base. We want blueberry plants to produce new canes, since older growth tends to become less fruitful over time.
'Alapaha' rabbiteye blueberry. (Photo source: Scott NeSmith, University of Georgia, Bugwood.org)
The LSU AgCenter and the LSU College of Agriculture