How To Grow Blueberry Bushes

Choosing Cultivars

Blueberry cultivars (varieties) widely vary between the U.S.D.A.’s agricultural hardiness zones. It is imperative that you choose a variety that not only is rated for your zone, but one that will produce the quality of blueberries that you desire. Berries Unlimited offers a wide variety of blueberry cultivar varieties for the U.S.D.A. agriculture hardiness zones 3 thru 10. If you are unsure of your hardiness zone, or just need help choosing which of the many fine varieties available to you, our staff will be more than happy to assist you in making the right choice.

Site/Soil

Blueberry bushes grow best in a sunny location, but will tolerate partial shade. Blueberries like any loose, well-drained soil, but prefer marginal, sandy, loam. They require acidic soil conditions. A pH reading of 5.0 is optimal, but any degree between 4.0 and 6.0 is acceptable. Soils not within the range of pH acceptability for blueberry bushes must be amended. Sulfur compounds such as elemental sulfur, or iron sulfate can be used to achieve this. On heavy clay soils, it is suggested that plants be grown on raised beds, 4 feet wide by 9 inches high for better water drainage. Raised beds are not recommended for production on sandy or loamy soils.

Planting

Berries Unlimited, recommends planting blueberry bushes 4 feet in the center, with a 36-inch buffer on each side of the plant to allow for mulching. An additional buffer can be added as required, to allow for access by equipment and/or human traffic. Planting holes should be dug wide enough to accommodate all the roots, and deep enough so that you can cover the uppermost roots with 3 to 4 inches of soil. Adding peat moss will aid in water retention, and increase the water holding capability of the hair root structure. Proper planting depth of blueberry bushes is critical. Plants should be roughly at the same level that they were in the container.

Mulching

Mulch will significantly increase blueberry bush growth and yield. Decomposing mulch not only helps improve soil structure, but also aids in the nutrient uptake of a blueberry bushes root system. Mulching maintains uniform soil moisture, reduces soil temperature, and controls the weeds. Berries Unlimited highly recommends using pine mulch, shavings or sawdust. When applying mulch, always keep the mulch a few inches away from the base of the bush. Better to leave 1-1.5 (depending on the size of the base of the plant) at the foot of " No mulch" area and try to keep this way at least until the plants are rooted in properly. Mulch four inches deep and twenty-four to thirty-six inches around blueberry bushes. Add additional mulch as needed.

Please, do not use cedar mulch or any colored mulch, do not apply any mulch until the plants are established! Keep 2 ft circle mulch free for a while.

Weed Control

Prevent weed growth around blueberry crowns by mulching, cultivating, or applying herbicides labeled specifically for use on blueberries. Do not cultivate more than two inches deep within rows, since most blueberry roots are in the top six inches of soil. To reduce root injury due to cultivation, a mulch within the rows is highly recommended to keep weeds down.

Pruning

A good-sized, healthy canopy is needed to support the growth of fruit. Pruning encourages production of large, high-quality fruit, and encourages earlier blooming. Fruit is produced on one-year-old wood. The largest berries are produced on the most vigorous wood, so a good supply of strong, one-year-old wood is desirable. When pruning, shape the bush by removing dead and diseased wood. Pruning new bushes is recommended to increase " production area" of the plants. Shape of the top of the bush should resemble an umbrella.  You can easily prune plants in about 2 weeks after picking the last berry. Find the tallest wooden branch, measure about 8 inches of the green part of the branch and prune the whole plant flat on this level. Prune the bushes annually. You can stop pruning after your plants are over 7-8 y.o.. Then, you can prune just dead or damaged branches. If the summer pruning was not done then prune very carefully while they are dormant, and before the buds swell. Please, do not prune wooden parts of the branches. Proper pruning should be done to maintain an adequate number of vigorous main stems, to prevent overbearing, and to stimulate new shoot growth.

Excessive pruning should be avoided because it greatly reduces the crop for that year. Keep the bush fairly open by cutting out any weak, old stems that no longer produce strong young wood at ground level. Keep four to six of the vigorous older stems and one to two strong new shoots per mature bush. The new shoots will eventually replace the older stems. Plants tend to overproduce. Often, if all the flowers are left to develop into berries, berries will be small and late ripening and plants will have little new growth. To avoid this, remove most of the thin, weak branches that have many flower clusters and few leaves. This type of pruning can be delayed until the extent of flowering can be determined. It is imperative to have a good balance between berry production and growth of vigorous new shoots to ensure proper yield of fruit.

Fertilization

Fertilizer application is often necessary to provide optimum level and balance of nutrients for blueberry bush growth. Poor vigor and leaf discoloration often indicate lack of fertilizer. Base initial fertilizer uses on the soil analysis. For established bushes, leaf analysis, soil analysis, and observation of plant vigor indicate fertilizer needs. Generally, one application in the spring of an acid-producing fertilizer each year will be sufficient. Do not fertilize after the blooming period, late fertilizing will encourage late growth in the fall, which in turn can cause winter injury. Nitrogen usually gives blueberries the greatest growth response. Nitrogen fertilizer requirements increase as the bushes grow older and yields increase. The nitrogen part in fertilizer should be in the ammonium form (ammonium sulfate). Please, use it VERY carefully. Better less than too much! Fertilizer containing nitrogen only in the nitrate form increases soil pH and should be avoided. Fertilizer formulated for acid-loving plants works well, such as an azalea fertilizer. Do not apply excessive amounts of fertilizer. Distribute fertilizer evenly within the root zone and avoid concentrating fertilizer near the crown of the plant.

Watering/Irrigation

Blueberry bushes require frequent watering since the root systems are shallow, usually less than 18 inches deep. Soil moisture content should not be allowed to become excessively dry. Reddened foliage, wilting, browning leaf margins, thin, weak shoots, early defoliation, and decreased fruit set are often symptoms of inadequate moisture. Water the blueberry bush frequently enough to keep the soil moist but not saturated. Blueberry bushes need at least 1 to 2 inches of water per week, do not apply water after early September unless soil is very dry. A rain gauge with a two-inch or greater diameter should be set up in the blueberry fields to track daily precipitation amounts. Blueberry bushes may be effectively irrigated by either sprinkler or drip irrigation systems. Drip systems deliver water under low pressure through small emitters. In this method, water is applied only within the rooting area. Since only the row area is wetted, foliage remains dry during irrigation, and weed development between rows is reduced. Mulching will help reduce the frequency of watering.

Pollination

Bees pollinate blueberry bushes. In many instances, wild bees will be present in sufficient numbers to pollinate the flowers. Bumblebees are more effective pollinators than honey bees. Some blueberry bushes do not absolutely require two different cultivars for cross pollination purposes. However, cross pollination with at least 2 different cultivars results in larger berries, higher yields, and earlier ripening. Alternate cultivars every 4 rows or every fifth bush.

Harvesting

Healthy, vigorous bushes usually ripen most fruit in two weeks or less. Plant more than one cultivar to extend the harvest season (recommended). The blueberry fruit turns blue before it is fully ripe. The acid level continues to fall for three to seven days after the fruit turns blue. The underside of the berry (the pedicel end) will turn from pink to full blue when it is fully ripe. Growers usually allow 20 to 30 percent of the crop to ripen before beginning harvest to avoid picking too much unripe fruit. Pickers should harvest only fully blue fruit. The berries do not ripen evenly on the cluster, so it is important to recognize and pick only the fully ripe berries. Pick only when dry, and keep handling to a minimum to preserve the whitish, waxy surface bloom of the berry which protects it from fruit molds. Cool blueberries promptly and store between 32 degrees and 40 degrees Fahrenheit.