Just About Any Home Garden Can Produce Blueberries

by G. J. Galletta and A. D. Draper.

Gene J. Galletta and Arlen D. Draper are Small Fruit Breeders at the Fruit Laboratory, Agricultural Research Service, Beltsville, Md.

Nearly everyone knows how great blueberries are in pies, muffins, pancakes, or as a fruit topping for break- fast cereals. However, most people have not experienced the delightful flavor and texture or subtle and delicate aromas of improved hybrid blueberries at the plump and proper stage of ripeness right from the bush.

Just about anyone in the continental United States should be able to grow prime blueberry plants in the backyard, or as a hedge along the property border.

Blueberries and other perennial fruit plants are often regarded as difficult to grow. But attention to a few facts about blueberries, and timely observance of a few practices, should result in excellent bush growth and fruit yields.

Blueberries vary in nature. Some are vine-like with creeping branches and some spread by underground rhizomes (prostrate stems). Plants may vary in height from two to eight feet. Plant shapes range from semi-upright to upright free-standing. Fruit is borne on perennial stout stems called canes.

Most cultivated blueberries are hybrids between two or more of the taller growing species and are referred to as "highbush blueberries." In the Southern United States it is also possible to grow selected hybrids of the very tall-growing blueberry species known as the "rabbiteye" or Southern highbush blueberry.

Blueberries have a mass of delicate and fibrous roots with no root hairs. The root system is confined to the upper foot of soil, usually the upper 8 to 10 inches. The root system is not a strong competitor, consequently blueberries thrive on open porous soils with a high water table and good drainage.

Like most other plants of the Heath family heather, azalea, cranberry, and rhododendron blueberries grow best in acid soils (pH 3.5 to 5.0, with 4.5 about optimum).

Many acid soils are light and sandy. Nutrients and water are generally held on the organic matter fraction of such soils. Consequently, heavier garden soils such as clay loams would need a fair amount of organic matter added to the blueberry planting area to increase the acidity, porosity, drainage and tilth of the soil.

Important aspects of blueberry culture are an acid soil requirement and a need for full sunlight for best flower bud development. For these reasons, never plant blueberries in an area which has been limed in the last 2 to 5 years, or near trees which shade the bushes, rob them of moisture, or prevent free air movement around the plants.

Free Air Need

Free air movement is especially important in the spring when early morning frosts can kill the flower buds. For this reason avoid low-lying planting sites with poor air drainage and increased frost hazards.

Highbush blueberries should be spaced 4 to 5 feet apart in rows 8 to 10 feet apart. Rabbiteye blueberries should be planted 5 to 6 feet apart in rows 10 to 12 feet apart. For hedgerows, highbush can be planted as close as 2 feet apart and rabbiteye 3 feet apart, but pruning must be more severe to provide the leaves and stems with adequate light.

Most highbush varieties will set fruit with their own pollen. For best fruit set, however, plant at least three varieties in any one location. Cross-pollination tends to produce larger fruits with more seeds which ripen faster and more uniformly than those which have been self-pollinated. Having several varieties in a proper ripening sequence yields fruit over a longer period.

At least two varieties of rabbiteye types must be planted together, since these varieties will not set fruit with their own pollen. The early rabbiteye varieties ripen 4 to 6 weeks after the early highbush varieties in eastern North Carolina.

Generally, highbush blueberries should be planted in areas having 160 or more frost-free days, with 800 to 1,200 hours below 45 F in the winter, and minimum winter temperatures of not less than 20 .

Rabbiteye varieties differ, but generally need 400 to 600 hours of winter chilling (below 45 F). It is not known how many frost-free days are required but the rabbiteye will grow between 30 to 37 parallels of latitude in acid soils at locations having mild winters.

Varietal choices for planting vary from region to region. The following are the better choices resulting from experience in separated test sites. New varieties are marked "trial" or "try".

Regional Varieties

Regional varietal choices for planting:

(1) North Florida, Gulf Coast, Lower Southwest, and extreme Southern California (San Diego and south)

Highbush try the new Flordablue and Sharpblue.

Rabbiteye Woodard, Bluegem, and possibly Tifblue; try the new Climax and Bluebelle.

2. Coastal Plain of Georgia, South Carolina (South of Charleston), Louisiana, Mississippi, Alabama, East Texas, Southern California (Los Angeles and south)

Highbush try Flordablue and Sharpblue.

Rabbiteye Tifblue, Woodard, Southland, Delite, Briteblue, Climax, Bluebelle, Garden Blue.

3. Mountain and Upper Piedmont of region 2 Highbush Morrow, Croatan, Harrison, Murphy, Bluetta, Patriot, Blue-crop, Berkeley, and Lateblue.

Rabbiteye same as region 2.

4. Richmond, Va., south to Piedmont and Coastal Plain Carolinas, Tennessee, lower Ohio Volley, east and south Arkansas, lower Southwest and mid-California Highbush Morrow, Croatan, Harrison, Murphy. Try Bluecrop and Patriot except in coastal plain areas.

Rabbiteye Tifblue, Woodard, Homebell, Southland, Garden Blue, Menditoo; try Climax and Bluebelle.

5. Middle Atlantic States, Midwest, Ozark highlands, mountain areas of region 4, northern California, Oregon, Washington Highbush (in ripening sequence) Bluetta, Collins, Patriot, Bluecrop, Blueray, Berkeley, Darrow, Lateblue, Elliott; (also older clones like Ivanhoe, Pemberton, Burlington and Dixi are good home garden types. Additionally, Herbert and Elizabeth have high dessert quality).

6. New England and cooler areas of Great Lakes States Highbush Bluetta, Collins, Patriot, Bluecrop, Blueray, Meader, Berkeley, and Northland.

Many poorly drained soils, especially in the South, are infested with a root-rotting fungus called Phytophthora cinnamomi. Almost all high-bush blueberry varieties are susceptible to damage by this fungus. An exception is the new resistant variety from the U.S. Department of Agriculture and the Maine Agricultural Experiment Station, named Patriot.

Most rabbiteye varieties are tolerant to the root-rotting fungus. It is also possible to buy plants of high-bush varieties grafted on suitable invigorating rabbiteye rootstocks like Garden Blue or Tifblue. Normally such plants are grafted to order, are more expensive, and need to be pruned differently than own-rooted plants.

Transplants

For most successful transplanting, order certified or State-inspected 2 year-old nursery plants in the 12- to 24-inch sizes. Three-year-old plants of up to 36 inches in height also transplant well. Plants older than 3 years or less than 2 years may die from water stress during the first growing season.

Before or shortly after transplanting, prune the plants to 3 or 4 strong shoots well spaced around the crown (stem base). Prune back each of the remaining shoots to remove the plump, rounded fruit buds. Cut to just above a vegetative bud (narrow and pointed bud), located preferably toward the outside of the stem.

In setting or planting, dig a hole 12 to 18 inches deep and 18 inches wide.

If your soil has a good organic matter content and the proper acidity (pH 3.5 to 5.0), thoroughly mix the soil taken from the hole and replace it along with the plant, setting the plants 1 to 2 inches deeper than they grew in the nursery. After planting, firmly press the soil around the plant with your feet, and water the area thoroughly.

Mulch the blueberry plants for at least 18 inches around the plants in all directions with 4 to 6 inches of well-rotted sawdust, peat moss, pine bark, pine straw, leaf mold, etc. Grass can be permitted to make a sod for walkways at the edge of the mulch if it is mowed during the growing season.

If you have a mineral soil low in organic matter, mix 1 cubic foot (2 to 3 shovels) of peat moss, rotted sawdust, or screened pine bark with the soil removed from the planting hole. Make sure the organic soil mixture is placed below, around and above the roots.

Sulphur can be used to make soil more acid. Add 1 pound per 100 square feet for sandy soils and 3 to 4 pounds per 100 square feet for loam soils, and work the sulphur into the soil before planting.

In areas with mild winters, you can either plant blueberries in the fall or you can plant fully dormant plants in the spring as early as the ground can be worked.

If blueberries are unmulched, cultivate them with a tined rake, fork, or hoe no deeper than 2 inches so as not to damage roots near the soil surface. Primary reasons for tilling the soil are to improve aeration and control weeds. Around mulched plants, either pull weeds by hand or gently hoe them out. Replenish the mulch at the rate of 2 inches per year.