11-08

How to Grow Blueberries in Central Florida

Central Florida has a warm, balmy climate with mild winters and sandy soils. While these may not seem ideal for growing blueberries (Vaccinium spp.), some varieties grow successfully in the area. Small adjustments in soil and care can lead to large blueberry yields in Florida's central region.

Low-Chill Considerations
Central Florida only gets between 100 and 300 "chill hours" each winter -- the number of hours below 45 degrees Fahrenheit. Blueberries need a certain number of chill hours to successfully bloom in spring. Two species of blueberries have low-chill cultivars that are adapted to mild winters: rabbiteye (Vaccinium virgatum) and southern highbush (Vaccinium darrowii). Most low-chill cultivars have been tested to grow near Ocala in central Florida or further north, but their southern limits have not been well tested.

Which Cultivars Work
"Emerald" highbush blueberry (Vaccinium darrowii "Emerald"), notes University of Florida, is the cultivar grown most often in the state. This early-ripening, high-yield bush produces a high quality berry from mid-April through mid-May and grows in U.S. Department of Agriculture plant hardiness zones 7 through 10. Rabbiteye cultivars generally need less maintenance, are more drought-tolerant and are more resistant to root root than highbush varieties. They must be cross-pollinated, which means you need at least two or three plants to produce fruit. "Brightwell" (Vaccinium virgatum "Brightwell") is a medium-sized blueberry that blooms between May and June. An excellent partner bush that flowers around the same time is "Austin" (Vaccinium virgatum "Austin") which has medium to large berries. Both grow in USDA zones 6 through 9.

Proper Location
Florida's soil is generally low in organic material and tends to be sandy, which means you need to amend the soil to keep blueberries happy. Incorporate an organic material, like peat moss or compost, into the top 8 inches of soil. An average 10- by 10-foot garden needs 8 cubic feet of compost spread over it and tilled in. Blueberries do best with a soil pH between 4.0 and 5.5. Pine mulch can help lower pH after planting. Place a 4-inch layer of pine needles or bark chip mulch in a 3- to 4-foot circle around each plant, keeping the mulch a few inches away from the blueberry stems.

Growing the Berries
Blueberry bushes can be quite large when mature. While highbush berry bushes tend to be smaller, a rabbiteye can grow up to 15 feet tall and 10 feet wide. Use a 7- by 7-foot area for planting rabbiteyes and a 4- by 4-foot area for highbush blueberries. If you wish to grow them as a clustered hedgerow, you may take this down to 3 feet for highbush and 5 feet for rabbiteye. Plant blueberries in full sun in soil that drains well through 18 inches deep. If the area has drainage problems, build a raised bed for the blueberries.

Pruning for Health
Pruning keeps your blueberry bushes healthy and productive, as berries grow best on young canes. When the plants are 4 years old or more, remove about one-fourth of the oldest canes every summer after harvest. This will also help to reduce the size of the canopy, keeping the berries easy to pick. To prevent the spread of diseases, soak your pruning shears in a solution of 1 part bleach to 3 parts water for five minutes. Rinse them with clean water and air dry them before and after each use.

Fertilizer Needs
Too much fertilizer can kill blueberries, so do several light applications each year. After planting, give plants 1 ounce per plant of 12-4-8 fertilizer with 2 percent magnesium, sometimes called a "blueberry specialty." Spread it in a 2-foot circle around the plant's center. In the second year, use 2 ounces per plant and spread into a 3-foot circle. From the third year onward, use 3 ounces of fertilizer in a 4-foot circle. Water the fertilizer in well after applying it. Repeat the process in April, June, August and October each year.