Raised beds help blueberry plants produce more fruit. Blueberry bushes, which develop in U.S. Department of Agriculture plant hardiness zones 3 to 9, have shallow roots which spread about 3 to 4 feet wide. The plants require well-draining, slightly acidic soil and direct sunlight to come up with strong fruiting canes. Bed sizes may vary, depending on the cultivar, but they should be at least 8 to 12 inches high and from 2 to 5 feet wide.
Soil
Blueberry bushes grow to several heights and, depending on the cultivar, need with pH of 4.5 to 5.5. Peat and muck soils are acceptable, notes University of California Cooperative Extension, but when the pH falls below 4.0, add some dolomitic limestone. If the pH is above 5.5, add elemental sulfur, aluminum sulfate or peat moss to acidify the soil. Make alterations into the ground in the raised bed a year before planting.
Size and Growth
Three main species of blueberry, with hundreds of cultivars, rise in Mediterranean neighborhoods and across the United States: High-bush (Vaccinium corymbosum), perennials which reach from 5 to 9 feet tall and 4 ft wide; Low-bush (V. angustifolium), growing up to 18 inches high; and rabbit-eye (V. ashei), that grows 3 to 6 feet high. Blueberry bushes have superficial, thin roots which develop in layers of soil. Since they don’t have root hairs to absorb water and nutrients, the crops are sensitive to environmental problems. Raised beds allow plant roots to spread and absorb moisture without drowning in water.
Raised Beds, Spacing and Construction
Soil beds of 8 to 12 inches high and 2 to 5 feet wide work well for many blueberry bushes. Ideally, mounds must be set about eight feet apart to permit root propagating and above-ground upkeep. The place and the amount of blueberry shrubs planted determines particular space requirements. Temporary beds made of compacted dirt mounds, with internal pockets of loose, tilled soil are not structurally contained. Though these temporary beds are easier and less expensive to build, they might crumble, erode or fall during the growing season. Instead, build raised beds using treated lumber, plastic, rubber, concrete blocks, bricks or stones. They hold the mounds in place, control sediment and continue indefinitely.
Planting
Plant dormant, 2-year-old, container-grown or bare-root blueberry plants in the ground in fall, winter or early spring to allow them to become recognized for the next growing season. Recommended planting times vary by climate and cultivar. Space the blueberries four to five feet apart. Placing the plants too deep into the ground slightly can smother origins, advises Oregon State University Extension, so put them just 3/4 inch deeper than their original containers. Firm the soil around them to eliminate air pockets. Water and prune the blueberries when you first plant them, but don’t add fertilizers. Blueberry bushes might take a year or more before they are ready to create fruit.
Bed Maintenance
Raised soil mounds heats up and dry out quickly, which may be a problem in the summertime heat. Employ an organic mulch to protect the soil from evaporation and help control weeds. Hay, straw and wood chips keep the soil cool while holding in water — mulch also keeps soil from absorbing too much water. Blueberry bushes require only moderate amounts of fertilizer so using a 10-10-10 mixture about four weeks after planting is typically enough. Pruning the plant and removing dead and diseased limbs promotes new stem growth and fruiting canes.