This popular insect-resistant shrub, growing six to ten feet high, bears plenty of fine-tasting fruit and adds beauty to the home when used as an informal hedge.
The cultivated blueberry is still close enough to its wild ancestors to be appreciative only of natural, organic fertilizers. They like humus and soft, woodsy soil so much that it is almost a question of growing them organically or not growing them at all.
In nature the blueberry plant displays its blossoms and tasty fruit in the seldom-frequented spots of forest and wilderness whose soil is covered with a rich blanket of decaying vegetation. It grows wild among the redwoods of California, on forest hillsides in New England and on the broad crests of the Appalachian ridges.
Soil should be of a pH from 5 to 5.6, which is quite acid. A liberal amount of peaty material is needed; a mulch of peat is fine. If additional acid is needed, use peat or compost made without lime to give the right acidity. The peat should be dug into the earth, and well intermixed with it.
Despite the need for moisture, blueberries require good drainage. Water should not stand on the surface. If you need to keep the water condition right, dig an open ditch or install tile drains. Cool, moist, acid conditions are needed in the soil for the best growth of roots to support the plants.
Upon arrival of plants (rooted shrubs) for setting out, it is urgent that the roots be protected from drying. Cover them at once with soil or burlap—if unpacked. Do not expose the roots to the drying effects of sun or wind. Put the plants in a cool moist cellar or in the shade till set. Dig the hole large enough to receive roots without bending or cramping them. When the subsoil is very hard, break it up at the bottom of the hole, using a pick or crowbar if necessary. Set the plants slightly deeper than they stood in the nursery and spread all roots out naturally. Place good surface soil next to the roots and work it in with the hands. When the hole is half-filled, tamp the soil firmly. Fill the hole and tamp the soil harder. Leave loose soil on top or cover with mulch. Leave a saucer like depression at the top to catch water. If manure is used, it should be well rotted and worked into and mixed with the soil. Manure can be used on top for mulch. Never put fresh or un-rotted manure next to the roots. It may heat or dry out and hurt the roots.
Careful planting is important and should never be hastily done. In all cases, pack the soil firmly about the roots and use moist soil for the purpose. Young plants, usually eight to 15 inches high, should be planted in early spring or late fall. Space them about five feet apart, with the rows about seven feet apart. Ten- to 15-year-old bushes usually yield about 14 quarts of berries.
Blueberries are not self-pollinating, so more than one variety should be planted. Since each of the common varieties has slightly different characteristics, it is good home-garden practice to plant a selection of different types. They ripen at different times and vary slightly in flavor.
For good pollination, encourage and protect bees wherever possible.
Preferred varieties in the two chief areas of high bush blueberry production are as follows:
Michigan-Early: Earliblue; Midseason: Blue Ray, Bluecrop; Late: Jersey, Coville.
New Jersey-Early: Earliblue, Blue Ray, Ivanhoe; Midseason: Bluecrop, Berkeley; Late: Herbert, Darrow.
Some of the older varieties like Concord, Rancocas, Weymouth, and Stanley do well in the northern and middle Atlantic states, because they usually produce smaller berries than the varieties listed above.
In the wild, blueberry plans are pruned by the “burning over” process on the managed areas; the old stems are burnt out. But in the garden the pruning shears need to be used after four or five years from set. Varieties vary greatly in growing habits. Some of the more open and flat-topped ones like Cabot, Herbert and Pioneer need very little pruning. The upright and close-growing varieties (Weymouth, Rubel and Rancocas), on the other hand, need considerable opening to prevent them from becoming too thick and bushy. A little attention to the natural degree of openness will suggest what thinning-out to do—if any is needed. It is well to compare and contrast different modes of growth before starting the pruning.
There are two types of growth to cut out in pruning—the very slender stems which may not bear much, and the oldest and largest that have borne several years and may not bear much more, except at the tips. It is well to keep the clumps fairly open to avoid crowding and shading. More than one foot asunder for all stems is too open; less than four inches is too close.
Blueberry Planting Problems
It is important to suppress all weeds. This is best done by the liberal application of acid mulches each year—peat and oak leaves are better than sawdust or pine needles. Compost is helpful. Woodland soil is often suitable for the plants.
Insect damage to blueberries is confined primarily to the blueberry fruit fly, whose eggs hatch into maggots inside the ripening berry, and the cherry fruit worm, a small red worm whose damage is usually confined to large commercial plantings. Best control of the fruit is rotenone dust, 25 pounds to the acre. It is applied five times between June and the end of harvest. Shallow cultivation also helps by imposing larvae to predator ants and birds.
The most troublesome blueberry disease is mummy berry, which causes berries to rot and fall off. Control by collecting old mummies off the ground or turning them under when cultivating.