Ferguson: Blueberries are a native treasure

Published 12:56 pm Friday, November 19, 2021

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The southeastern United States is home to a number of native blueberries and blueberry relatives. A walk in the neighborhood where I grew up can yield sightings of Elliott’s blueberry (Vaccinium elliottii, which we called huckleberry), farkleberry (also known as sparkleberry and tree huckleberry, V. arboreum), and the low-growing Darrow’s blueberry (V. darrowii).

The blueberry varieties that have traditionally been planted in the Deep South are rabbiteye blueberries (V. ashei a.k.a. V. virgatum), and with good reason. These plants are forgiving of less-than-ideal soil conditions and can live for many years. Common varieties include “Premier,” “Tifblue,” “Climax,” “Brightwell” and “Powderblue.” A number of newer varieties have been released within the past 30 years, and some of these are currently being evaluated at the Hammond Research Station.

Southern highbush blueberry varieties like “Star” and “Legacy” are crosses between the northern highbush blueberry (V. corymbosum) and species native to the southern U.S., such as V. darrowii. These fruit earlier than rabbiteye varieties and dominate the commercial blueberry industries in states like Georgia, Florida, and North Carolina. However, they’re more finicky about soil conditions than rabbiteye blueberries are. Having an appropriate soil pH and good drainage are critical when growing these. They also tend to be more susceptible to diseases.

Soil for rabbiteye blueberry plants should be well-drained and have a pH between about 4.5 and 5.3. Much of Tangipahoa and Washington parishes have soils with pHs that are naturally in this range, but if you live in an area where soil tends to be less acidic, or if you’ve limed the soil in the past, you may need to adjust it before planting. If soil pH is too acidic (below about pH 4.0), lime may actually be needed to raise pH.

Additions of elemental sulfur (to reduce pH) or lime (to raise pH) should be made several months before planting and based on a soil test report. Adding too much can result in excessively low or high soil pH.

To improve drainage and add organic matter on the site where you want to plant blueberries, you can till in two to four inches of pine bark and mound soil to form a raised bed six to 10 inches high.

While containerized plants can, with enough coddling, be planted at pretty much any time, planting between late fall and early spring allows them to grow some roots before summer heat arrives. Bare root plants should be planted while dormant.

Plant at least two rabbiteye blueberry varieties for cross-pollination and maximum productivity.

If planting in a row, space rabbiteye plants five to six feet apart. If you have multiple rows next to each other, leave about 12 feet between row middles to allow space for picking, mowing, and sunlight penetration.

Remove about one-half of the above-ground part of the plants before or just after planting. If plants flower during their first growing season, remove the blooms so that plants can put their energy into getting established instead of into flowering and fruit production.

After planting, spread mulch to a depth of about four inches around the plants. Mulching helps prevent weed growth and maintain soil moisture, and as mulch decomposes, it adds organic matter to the soil.

Wait until new growth begins, and at least one to two months after planting, to apply any nitrogen-containing fertilizer. At that time, one tablespoon of 13-13-13, 1.2 tablespoons of 10-10-10, or 1.5 tablespoons of 8-8-8 can be spread around each newly planted bush. Wait four to six weeks and then apply 0.75 tablespoon ammonium sulfate (21-0-0), 0.5 tablespoon 33-0-0 (urea-ammonium sulfate), or 0.33 tablespoon of urea. One to two additional applications can be made at least four to six weeks apart, but avoid applying fertilizer after early September. Spread fertilizer out over a circle of about 180-inch diameter instead of concentrating it at the base of the plant. Blueberries are sensitive to over-fertilization.

Let me know if you have questions.

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