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Blueberry flowers and fruit form on stems that grew the previous summer.
Photo by S. Cory Tanner
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Pruning the oldest and tallest stems from a blueberry bush makes room for young fruiting stems. Cut old stems close to the soil surface to allow new fruiting stems—identified by their reddish-brown bark—to grow.
Photo by S. Cory Tanner
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Cutting back strong vertical shoots encourages branching and increased fruit production.
Photo by S. Cory Tanner
Blueberries are popular backyard bushes for good reasons: They are easy to grow, bear nutritious fruit, have few pest problems and make attractive landscape plants.
Give them proper conditions at planting, and your blueberry bushes will produce well for many years with relatively little care. In fact, an early spring fertilization every year and light pruning once or twice a year are the biggest chores.
Understanding how blueberry bushes produce fruit will help you master their fertilization and pruning needs. They fruit on 1-year-old shoots—stems that were produced the previous spring and summer. Sturdy shoots that grow 6 to 12 inches in the spring will produce the best fruit the following year, so you want to manage your plants to produce vigorous shoots each year while not pushing excessive growth.
Fertilizing your plants is a double-edged sword. It encourages new growth, which is good, but overfertilization will result in excessive growth and decreased fruit production. If you haven’t done so in several years, take a soil sample from around your blueberry planting and submit it to a Clemson Extension office. This is your best way to determine how much fertilizer is needed.
Generally, blueberry plants more than 3 years old will need about one-half cup of a complete fertilizer, such as 10-10-10, each year. Spread this dose within a 3-foot circle around each plant in March, just as new growth begins to emerge. Your plants should produce 6 to 12 inches of new stem growth by June, but if they don’t, side-dress the plants with one-half cup of calcium nitrate or similar fertilizer. Do not fertilize after July 1.
Pruning seems like a daunting task, but it really isn’t. If your blueberry plants are less than 5 years old, they will require very little pruning. In late winter, just remove any broken or dead stems and weak, lower growth. Stems in the lower half of the shrubs may be shaded by the foliage above, leading them to become twiggy and less productive.
It can also be helpful to selectively remove one or two of the oldest stems in the center of the plant. This allows more light into the center and encourages production of new shoots. Finally, cut back any excessively long and limber shoots during the early summer and right after harvest. This will encourage branching and multiply the productivity of those shoots the following year.
Older blueberry bushes can grow larger than you might like and become less productive. For rabbiteye varieties (the most common type grown in South Carolina), this happens after the plants are about 5 years old. Judicious pruning is just what these plants need.
It’s easy to spot the oldest stems on your overgrown blueberry plants— they are the least productive and the tallest. These are the stems you want to remove. You can remove up to one-third of these in any one year without damaging your plants. If you’ve kept up with pruning each year or have plants that are only 5 or 6 years old, you may need to remove only one or two stems. Sturdy loppers will remove these stems all the way back to the ground or to a side stem that emerges a few inches from the soil line. Late January to early March is your best window for this work.
Keep up with these simple tasks, and you’ll have a bounty of blueberries for summer pies and breakfast cereals.
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S. Cory Tanner is an area horticulture agent and Master Gardener coordinator for Clemson Extension based in Greenville County. Contact him by e-mail here.