Tickling the shrubs for the blue jewels of summer

Gardeners looking to tickle their taste buds as well as their eyes and noses, should consider planting blueberries.

The easiest of all fruits for North American gardens, blueberries are our only native fruit to become a cash crop. The modern hybrids grown commercially for their larger berries are only a few steps removed from the wild species still found in much of the country, and there are varieties for just about every climate and region.

Northern gardeners mostly use varieties of highbush blueberry (Vaccinium corymbosum), 4 to 7 feet tall, and lowbush blueberry (Vaccinium angustifolium), 1 to 2 feet tall. For Southern climates, rabbiteye (Vaccinium ashei) - 8 to 20 feet tall - is the preferred species.

Blueberries' only real demand is acidic soil. Otherwise, they're about as relaxed and easy-care as plants can get.

Blueberry bushes are also very attractive. Their leaves are small, green ovals that can be used to make tea. I rave over them, but most people find them understated.

In spring, plants have clusters of tiny white bell-shaped flowers like those of Pieris japonica (to which blueberry is related). They have blazing red foliage in fall, and graceful, reddish-brown branches (on some varieties, they're brilliant scarlet) in winter.

But they're in their glory in summer, when the berries ripen from green to purplish to dusky blue. A bush loaded with blueberries is a beautiful sight, says Alan Haig, owner of the Home Orchard Company in New York State and an instructor at the New York Botanical Garden.

Mr. Haig is serious about getting plenty of produce from his bushes. The only real pest these sturdy plants have is songbirds, which adore blueberries as much as people do and are more diligent about picking them.

Most gardeners attempt to foil the birds by casually tossing some net over their bushes and maybe tying it down. I do nothing at all to my bushes and claim I planted them to attract birds to my city yard.

"But net," says Haig, "only slows the birds down." It doesn't completely deter them. He has built a PVC shelter around his bushes, which he drapes the net over.

Blueberries for North and South

Haig plants a wide variety of highbush cultivars that fruit all through the season, from the early varieties - Duke, with extra-large berries, Patriot, and Bluejay - to the latest, Elliot, which fruits in September in the Northeast.

Midseason varieties include Bluecrop, a vigorous grower with good fall color that bears for a long season; Berkeley, an attractive, fast-growing plant whose berries have excellent taste; and Darrow, which bears the most delicious fruit of all, says Haig, but yields fewer berries and is a more finicky plant.

An old favorite, Jersey, which has berries of only average taste and minimal fall foliage color, is perhaps the most widely grown, Haig believes, because it's a reliably heavy cropper.

The best choice for gardeners in the South is rabbiteye blueberries, since they are native to that region. Also used in some areas of California, rabbiteyes bloom earlier than the highbush varieties and require at least half a day of sun for best performance. Recommended cultivars include Briteblue, good for home gardeners because the berries last a long time on the plant, and the later-bearing, widely planted Tifblue.

"The best thing about having your own blueberries," says Haig, "is that you can leave them on the bushes a long time, until they get really sweet." The berries on both Northern and Southern plants aren't fully ripe until a few days after they turn blue, he says. If you tickle a cluster, the ripe ones will come off in your hand without pulling.

Blueberries, particularly the two Northern species, require acidic soil. The pH should ideally be 4.5 to 5.5; if yours is higher (more alkaline), it's best to prepare a bed by mixing sulfur into the soil at least four weeks before planting. Mix in peat moss, also, to provide organic matter, which helps the plants tolerate less acid soils.

Blueberry care

Blueberries accept all moisture levels from wet to dry, provided the soil is well-drained.

They produce the most fruit in full sun. Plants will remain healthy in considerable amounts of shade, but will produce fewer berries.

Peat moss alone will acidify soil only temporarily; aluminum sulfate (the same chemical used to turn hydrangea flowers blue) is a better acidifier, Haig says.

Because blueberries have shallow, fibrous roots, they benefit from mulch to keep the soil from drying out.

It's best to plant at least two different varieties. Rabbiteyes in particular do better with at least three shrubs of two different cultivars. Cross-pollination between the different varieties increases berry yield and size.

Unlike blackberries and currants, which are ramblers, blueberries do well in containers; they don't need to roam.

Consider blueberries as a versatile addition to your landscape, rather than just a fruit.

Blueberries are handsome enough to use as specimen plants, are happy in containers, look great in a naturalistic planting, and make a hedge that provides food and fabulous fall color, which is more than you'll get from a privet.

(c) Copyright 2001. The Christian Science Monitor