By Nancy Hawkins
UCCE Master Gardener
Let’s talk blueberries. I planted six one-gallon size plants about a year ago with big expectations. No blueberries yet. So, I decided to do some research to find out why.
Blueberries belong to the family Ericaceae, which includes azaleas and rhododendrons. Most gardeners will recognize this plant family as one that does best in acidic soil (pH of 4.5-5.5). Traditionally, blueberries have been grown most successfully in the northern U.S. where a high number of chilling hours are available. However, in recent years, much work has been done to produce varieties of plants that will tolerate the low amount of chilling hours common in many parts of California.
There are many varieties of blueberries available to us in the Central Valley. One might want to select varieties that ripen at different times to extend the harvest season, feature large fruit (best for fresh-eating and desserts) or small fruit (best for baking in muffins and cooking in pancakes). Bushes with brilliant fall colors or different growth habits offer the gardener many choices to use throughout the landscape. Most local nurseries make it a point to carry low-chill cultivars that have been tested in our area and do well here with our warmer winters and hotter summers. When Bravo Lake Botanical Garden in Woodlake hosted a Berry Tasting Event for the public in 2014, I tasted several while staffing a Master Gardener booth at the event, and came up with a list of the varieties that I liked the best.
Here are my favorites, listed in order of ripening:
- Early Blue has medium-sized, loose clustered, light blueberries with sweet flavor. They are vigorous, erect, productive but very susceptible to root rot.
- Misty has medium-large berries of excellent quality.
- Southmoon is early-bearing and Reveille produces large, dark, sweet berries later in the season.
- O’Neal was one of the first blueberries introduced into California for home gardeners, and is still a good choice for quality fruit.
- Sharpblue, Star, Emerald and Jewel are other recommended varieties.
Blueberries need a sunny location and grow best in sandy, well-drained soils that are kept moist throughout the growing season. Contrary to popular belief, blueberries do not do well in saturated or poorly drained soils, or in the shade. Soil conditions must be modified when planting blueberries to lower the pH to 4.5 – 5.5 and to improve drainage. If the pH is above 5.5, acidify the soil before planting by mixing in 4-8 pounds of soil sulfur or 6-12 pounds of aluminum sulfate per 100 square feet of soil. Another option is to incorporate 4 to 6” of peat moss in the top 6 to 8” of soil. Adding humus and organic matter will improve drainage and will also favor the growth of blueberry roots.
Blueberries should be planted in raised beds and can be planted as close as 2½ feet apart to form solid hedgerows or spaced up to 6 feet apart and grown as individual specimens. If planted in rows, allow at least 6 feet between rows. Blueberries can also be grown in large pots, where it may be easier to maintain a low pH and acid soil. If you grow them in pots, make a potting mix comprised of 1⁄3 pathway bark (½” size), 1⁄3 coarse peat moss, 1⁄3 leaf mold or forest humus based potting soil. After mixing the ingredients, add 2 Tablespoons of soil sulfur.
To plant blueberries, gently remove the plant from the grower’s pot and lightly roughen up the outside surface of the root ball. Set the top soil line of the plant about 1-2 inches higher than the existing ground to allow for settling and the application of mulch. Mound the soil up along the sides of exposed root mass. Firm soil around roots and water well. Blueberries do best with 2 to 4” of mulch over the roots to conserve moisture, prevent weeds and add organic matter. Mulch can consist of bark, pine needles, acid compost, or sawdust. All will work well.
It will take at least three years for a blueberry plant to become established and healthy. (That’s my problem! My plants are only one year old!) Remove all blossoms as they appear in the first two years. Prune off any diseased and damaged wood during the first dormant season. After their second year, blueberries should be pruned annually. Blueberry plants have a naturally bushy form, but limit the number of branches to the age of the plant, up to a maximum of 6 to 8 branches for old bushes. Yearly, remove 1-2 branches so that no branch is over 4-6 years old. Prune out suckers and weak wood, especially from the top of the plant.
Blueberries like acid fertilizers such as Rhododendron/Azalea/Camellia formulations. For newly planted stock, use 2 tablespoons per plant of 10-20-10 (or similar fertilizer), in late spring or once plants are established. In subsequent years, apply 3-5 tablespoons per plant in early spring and again in late spring, and always water after fertilizing.
Now I know I need to wait a few more years for my plants to be productive. In the meantime, I will water, fertilize, prune, and dream of fresh blueberries on ice cream.
The UCCE Master Gardeners will be available to answer your gardening questions each Saturday at the Visalia Farmer’s Market in the Sears parking lot from 8 to 11 a.m.