24 March 2008
Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580 fax: 434.872.4578
Many home gardeners in Virginia have been successful with highbush blueberry plantings. Although they may be grown in any area where native blueberries, azaleas, mountain laurel, or rhododendrons do well, they have a better flavor when grown where nights are cool during the ripening season. They are very exacting in soil and moisture requirements, but require little protection from insect and disease pests.
To provide adequate cross-pollination and to increase chances for a good crop of fruit, two or more varieties of blueberries should be planted. Blueberries should be planted where they have full sunlight most of the day and are far enough from the roots of trees to avoid competition for moisture and nutrients. They are shallow-rooted plants and must either be irrigated, heavily mulched, or planted in a soil with a high water table. Adequate drainage must be provided, however, because they cannot tolerate saturated soils.
They grow best in porous, moist, sandy soils high in organic matter with a pH range of 4.2 to 5.5. Have the soil tested, and if it is not acid enough for blueberries, work such materials as peat moss, oak leaves, pine needles, or sulfur into the area where the plants are to be set. This should be done six months to a year before planting. To acidify sandy soils, sulfur is recommended at the rate of 3/4 pound per 100 square feet for each full point the soil tests above pH 4.5. On heavier soils use 1 1/2 to 2 pounds. Once proper acidity is established, it can be maintained through the annual use of an acid fertilizer, such as ammonium sulfate or cottonseed meal.
Vigorous, 2-year-old plants about 15 inches high are recommended for planting. Set in early spring about three or four weeks before the average date of the last frost. Blueberries are usually planted every 4 feet in rows 6 feet apart.
Give the roots plenty of room. Where the plants are to be set, dig the holes wider than and as deep as necessary to accommodate the root systems. It is not necessary to incorporate organic matter or other soil amendments into the backfill soil. Trim off diseased and damaged portions of the top and roots, and set the plants at the same depth that they grew in the nursery. Spread the roots out, and carefully firm the soil over them. Water the plants thoroughly after planting.
Mulching is the preferred soil management practice in a blueberry planting. The entire area around and between the plants should be mulched. Hardwood or softwood bark applied to a depth of 3 or 5 inches is recommended. Renewed annually, this heavy mulch retains moisture, keeps the soil cool, and adds needed organic matter.
No fertilizer should be applied at planting time, and usually none is needed during the first growing season. On weak soils, however, the application of 2 ounces of ammonium sulfate around each plant about the first of June is beneficial.
Ammonium sulfate, at the rate of 2 ounces per plant, should be spread in a circle around each plant about 6 to 8 inches from its base just before the buds begin to swell the second spring. Increase the amount each succeeding spring by 1 ounce until each mature bush is receiving a total of 8 ounces annually. Cottonseed meal has proven to be an excellent fertilizer for blueberries and is used by many home gardeners. It supplies the needed nutrients and helps maintain an acid soil. Use it at the rate of 1/2 pound per plant. The rate should be doubled when the plants come into bearing.
Until the end of the third growing season, pruning consists mainly of the removal of low spreading canes and dead and broken branches. As the bushes come into bearing, regular annual pruning will be necessary. This may be done any time from leaf fall until growth begins in the spring. Select six to eight of the most vigorous, upright growing canes for fruiting wood and remove all others.
After about five or six years, the canes begin to lose vigor and fruit production is reduced. At the dormant pruning, remove the older canes of declining vigor and replace with strong, vigorous new shoots that grew from the base of the bush the previous season. Keep the number of fruiting canes to six or eight, and remove the rest. Head back excessive terminal growth to a convenient berry-picking height.
Birds are by far the greatest pests in a blueberry planting. Covering the bushes with wire cages, plastic netting, or tobacco cloth is perhaps the best method of control. Aluminum pie tins have been used successfully. They are suspended by a string or wire above the bushes in such a manner that they twist and turn in the breeze and keep the birds away.
Some varieties of blueberries will bear the second year after planting. Full production is reached in about six years with a yield of 4 to 6 quarts per plant, depending on vigor and the amount of pruning.
Blueberries hang on the bushes well and are not as perishable as blackberries or raspberries. Picking is usually necessary only once every five to seven days. Blueberries will keep for several weeks in cold storage.
For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.