LSU AgCenter's Weekly Message

You Can Prune and Fertilize Blueberries After Harvest + Pruning Demo Announcement

In Louisiana, we have a long enough growing season that we can prune blueberry plants shortly after harvest and get regrowth and flower bud development on the new growth. On the other hand, if you wait until wintertime to reduce bush height, you’ll likely be cutting off already-developed flower buds that could have produced fruit.

As a rule of thumb, prune blueberries for height as soon as practical after you finish harvesting and no later than the end of July.

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 on after they’re pruned will depend 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.

Besides reducing plant height for ease of picking, the other major step to pruning mature rabbiteye blueberry plants is to remove one to three of the oldest canes each year. This allows more light into the bush so that fruit isn’t just produced on the outside of the canopy. It also encourages plants to grow new canes from the base. We want blueberry plants to produce new canes, since older growth tends to become less fruitful over time.

You can remove several old canes either after harvest 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.

After harvest is also a good time to make the final fertilizer application of the season. (The first one can be made in the late winter or early spring, around the time the plants start to grow.) For a mature blueberry bush, one option is to use 1 cup 8-8-8 per plant or, if you used a “complete” fertilizer like 8-8-8 or 13-13-13 earlier this year, one-third of a cup of 33-0-0 (urea-ammonium sulfate) or ammonium sulfate. Rates for younger plants should be lower. Spread fertilizer out under and around the canopies.

On Wednesday, July 8, at 9 AM, we’ll have a blueberry pruning demonstration at the Hammond Research Station (21549 Old Covington Hwy., Hammond). If weather doesn’t allow us to be outside, I’ll do a presentation indoors.

Let me know if you have questions.

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Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).