Dominic A Marini
Regional Fruit & Vegetable Specialist
Extension Region (Retired)
Cultivaled blueberry bushes in the home gardens are desirable from two standpoints - they provide variety in the diet and provide attractive fall foliage and winter twig colors in the landscape. Not all soils are suitable for blueberries, but with proper management, they will grow on most soils.
The notion that cultivated blueberries do not have as good flavor as wild berries is a fallacy, the reason being that most cultivated berries are harvested before they are completely ripe in order to get them before the birds do. Some varieties are not fully ripe until two weeks after the berries turn blue.
Birds: The number one problem for the blueberry grower is birds. Do not even consider blueberries unless you are prepared to protect them. Noisemakers, scarecrows and other frightening devices are useless. At present, the only succesfulful means of protecting the crop is to completely enclose the planting to exclude the birds. The most practical method is a framework of posts and either furring strips or wire covered by chicken wire or plastic netting.
Soils: The blueberry is a shallow-rooted plant. Therefore, it requires a soil that has good moisture-holding capacity but is also well drained. Blueberries do not like wet feet. Even when growing in swampy areas, blueberries are always found on hummocks with their roots close to but not in, the water. A good supply of organic matter improves the water-holding capacity of a dry, sandy soil and the drainage and aeration of a heavy, wet soil.
Commercial plantings are not recommended for sandy or gravelly soils. However, it is possible for the home gardener to grow a few bushes in soch a soil provided that a generous supply of organic maner is incorporated into the soil when the bushes are set, the bushes are well-mulched, and irrigation is applied during dry periods.
Blueberries thrive in acid soils. A pH range of 4.5 to 5.0 is ideal, but the higher the organic matter content of the soil, the wider the pH range that will be tolerated.
Varieties: In Massachusetts, early varieties are ripe the first week in July, while late varieties bear into October. Therefore, it is advisable to plant several varieties, not only for a continuous supply throughout the season, but also for cross pollination to insure maximum production. Some varieties, such as Berkeley, are ripe as soon as they turn blue, while others, such as Coville, must remain on the bush for up to two weeks after turning blue before they are ripe.
Varieties recommended for Massachusetts include: Bluejay, Duke, Patriot and Spartan - early; Berkely, Bluecrop, Blueray and Nelson - mid season; and Coville, Herbert, Jersey and Lateblue - late.
Planting: Two-year old bushes, 12 to 18 inches tall, are recommended. Bushes this size are easy to handle, readily become established, make rapid growth and start to bear within a year or two. Any blossom, developing on newly set plant, should be removed to allow maximum growth, A few berries may be produced the following year with production increasing each year thereafler until mature size is reached at about 6 years when a bush may produce 7 to 8 quarts.
Plants should be set as early in spring as possible. Dig a hole twice as wide and twice as deep as the roots of the plant. Prepare a planting mixture of 2 parts loam and one part oak leaf mold, peat moss, aged sawdust, or compost, and place a layer of this mixture in the bottom of the hole.
Set the bush, with its roots spread out, at a depth of one inch more than it grew in the nursery and pack the hole tightly with soil.
Bushes are commonly spaced 5 feet apart in the row, with 8 feet between rows, Some growers prefer wider spacings of up to 12 by 18 feet.
Culture: There are three soil management system, used for growing blueberries - sod culture, clean culture, and mulch culture.
Sod culture is the simplest system. The grass is mowed in the aisles between the rows and around tbe bushes. However, the sod competes with the bushes for moisture and nutrients.
Clean cultivation is the usual method in large, commercial plantings in New Jersey, but is little used in Massachusetts. Frequent cultivations are necessary to keep weeds under control. With the increasing use of chemical weed killer, fewer, cultivations are needed to control weed growth.
Few plants respond to mulch as well a, blueberries. A good mulch conserves moisture by preventing evaporation from the soil surface and is particularly beneficial on light sandy soils. It also suppresses weed growth and releases nutrients to the plants as it decomposes. Sawdust, woodchips, ground bark or peat moss are excellent materials for mulching blueberries. A layer 3 to 4 inches thick is desirable and should be replenished every few years to replace that which is lost through decomposition. Where mulching materials are scarce, a combination of mnlch around the bushes and sod or clean cultivation in the aisles may be used.
Fertilizing: Since blueberry bushes bear fruit on the previous season's growth, they must be fertilized generously to promote vigorous annual growth.
Newly set bushes should not be fertilized until the start of new growth about one month after setting. Then apply 1/2 ounce of a 10-10-10 fertilizer in a band around the plant 6 to 12 inches from the crown.
The following year, apply one ounce per busb at bloom, and increase the rate by one ounce each year thereafter to a maximum of 8 ounces for mature bushes. These rates are guidelines and may be increased or decreased depending on the growth of the bushes. Other fertilizers may be substituted such as 5-10-10, or sulfate of ammonia, provided that the same amount of nitrogen is applied.
Pruning: This is one of the most important, least understood, and most neglected aspects of blueberry culture. Blueberries tend to overbear and when this happens year after year, new growth is suppressed, bushes lose vigor and become unproductive. In extreme cases berries remain small and fail to ripen. On the other hand, pruning stimulates growth and increased productivity.
In pruning, strive to achieve a balance between fruit and new growth. First, cut out dead, broken, short, weak, spindly shoots, On mature bushes, remove about 1/3 of the oldest shoots each year to make room for new, vigorous ones to produce the crop.
Varieties differ in their growth habits. Some produce new shoots from the crown profusely and can be pruned more severely, while others produce new shoots sparingly and must be pruned more judiciously.
For maximum fruit size, cut back fruiting shoots, leaving 4 or 5 fruit buds per shoot.
Pruning should be done in late winter or early spring before new growth begins. Any pruning is better than no pruning; any cut is a good cut. It is impossible to harm a bush by pruning. In fact, a bush can be cut to the ground and a new bush will arise from the crown.