The blueberry is a small fruit that is very popular, but can be challenging and frustrating for some home gardeners.
Blueberries require acidic soils with high organic matter content. They can be injured by late-spring and early fall frosts and also midwinter temperatures below negative 20 degrees Fahrenheit. Blueberry plants are also expensive -- 2- or 3-year-old plants can cost over $7 per plant.
Blossom removal is recommended for the first 2 years after planting in order for the plants to channel energy into shoot and root development. Hence, there is no crop for the first two years.
The yield tends to be low during the third year after planting, averaging about one-half pound per plant and reaching a peak of 5 pounds per plant in bushes that are more than 6 years old after planting.
Home gardeners need to select the correct varieties, the best location, amend the soil to the proper pH level, plant at the right spacing and depth, and care for blueberries until the berries are ready for harvesting.
Variety selection: Choose varieties that are adapted to your region and intended for use there. Blueberries are self-fruitful (pollen from the same cultivar can pollinate flowers of same cultivar to form fruits), but planting two or more varieties that ripen at different times can extend the harvest season.
Location: Plant blueberries on a site where they can get full sun; that is, at least 6 hours of direct sunlight in a day. Plant blueberries away from tall trees and shrubs.
Soils: Blueberries require well-drained soil with acidic pH and do well in sandy soils with high organic matter content. Test the soil and adjust pH to the 4.5-5.2 range. If the pH is below 4.0, incorporate finely ground dolomitic limestone based on soil test results (about 5 to 10 pounds per 100 square feet). If the soil pH is above 5.2, add elemental sulfur to lower the pH, and about 1 to 2 pounds of elemental sulfur is needed to lower the pH by 1 unit (such as from pH of 5.5 to 4.5). If the pH of established planting is slightly over 5.2, continued use of ammonium sulfate will eventually reduce it. Plant cover crops or add organic matter by incorporating peat, bark mulch or straw in the soil before planting.
Planting: Purchase 2- or 3-year-old seedlings that are healthy and disease free. Plant in early spring as soon as the ground can be worked. Plant 4 to 6 feet apart within the row and plant closer on less fertile soils. The rows should be spaced 10 to 12 feet apart. Plant 1 to 2 inches deeper than they were grown in the nursery. Pat the soil firmly around the base of the plant and water immediately after planting.
Watering: Blueberries have fibrous root systems, and they are shallow rooted. Irrigate during dry weather using overhead or drip irrigation. Soak the soil to ensure that the roots within the 12- to 16-inch depth are watered.
Mulching: Use organic mulches such as sawdust, bark, wood chips, straw or leaves. Spread the mulch 6 to 8 inches thick around the base of the bushes to control weeds and conserve moisture. The nitrogen fertilizer requirements in mulched plantings may be two to three times higher so the amounts applied need to be adjusted.
Fertilizing: One week after planting, apply 1 ounce of a magnesium-containing fertilizer such as 20-0-10+5 (N-P-K-Mg) in a band within 12 to 18 inches from the base of the plant. In established plantings, apply ammonium sulfate every year just
before growth resumes in early spring to supply nitrogen based on the age of the planting. The ammonium sulfate requirements will be met as follows: 3 ounces for 2-year-old planting, 8 ounces for 4-year-old planting, and 12 ounces for a planting 8 or more years old.
Weed control: Control perennial weeds before planting. Control weeds that emerge during the first year after planting by cultivation. Avoid root injury by cultivating no deeper than 1 to 2 inches as blueberries are shallow rooted. Put mulch around the base of the plants to control weeds. Herbicides can be used for weed control, but remember to read directions on the label before purchasing or applying any pesticide.
Pruning: Blueberry bushes are best pruned when dormant in early spring. Young bushes require less pruning during the first 3 years. Prune young bushes by removing damaged branches and spindly growth around the base of the plants. Mature bushes are pruned annually.
Pollination: Although blueberries are self-fruitful, higher production has been reported where two or more different varieties are planted in the same patch. Blueberries require bees for pollination. Cold weather or rainy or windy conditions can slow bee activity and may lead to poor fruit set. Do not spray insecticides when plants are in full bloom.
Harvesting: Protect mature fruits from birds by covering with nets. Blueberries may require two to four pickings as the fruits ripen over several weeks. Pick only fully ripe berries. Hand pick by gently rolling the berries between your thumb and forefinger. Place fruit gently into pint containers, cover the containers and refrigerate at 55 degrees F.
