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Small Farm Program Research
Extended Season Fresh Market Blueberry ProductionA New Alternative Crop for California
Mark Gaskell, Ph.D.
A blueberry field day was held in mid-November 1998 at the farm of Jennifer and Chuck Lenet near Cayucos and the farm of Marilyn Scoggins near Morro Bay. The Central Coast Chapter of California Rare Fruit Growers sponsored the field day. Author Mark Gaskell, farm advisor with UC Cooperative Extension, summarized results from the trials to date. Chuck, Jennifer, and Marilyn shared their experiences thus far with pushing blueberries into new production environments.
Visitors had a chance to become familiar with blueberry cultivation requirements and to sample the harvest of beautiful November blueberries. Several cultivars were producing in mid-November including Gulf Coast, Cape Fear, Sharpblue and Georgia Gem. And differences in fruit ripeness at the two sites indicated a relationship between pruning time and fruit set and ripening. The most promising results to date are from the group of low chill Southern Highbush blueberry cultivars. The cultivars tested thus far that show great promise include Sharpblue, Georgia Gem, Gulf Coast, Cape Fear, Marimba, and Misty. The cultivars O'Neal, Ozark Blue, and Sierra are also being evaluated, but it is too early to identify the long-term advantages and disadvantages of each cultivar.
These blueberry cultivars include larger plant types such as Sharpblue, Marimba, and Georgia Gem, which can be planted on spacing of 36 inches to 48 inches between plants in a row. Smaller statured plant types such as Misty, Cape Fear, and Gulf Coast may be spaced as closely as 30 inches between plants. Many of the Southern Highbush cultivars appear to require very little if any chill. In mild coastal areas of California, these cultivars exhibit frequent flowering and fruiting cycles. Flowering may be managed in large part by pruning. Once pruned, plants pass through a period of vegetative growth during which new canes are initiated. Following the flush of new vegetative growth, flowering begins and fruit set and ripening are determined primarily by temperature.
Successful blueberry cultivation in many parts of California requires special soil and land preparation. Blueberries grow best in an acid soil environment (below pH 5) and many California soils range from pH 6.5 to 7.5. The soil pH should be amended with applications of peat in the initial planting hole and elemental sulfur or other forms of sulfur in the surrounding soil. The amount of sulfur to apply will vary with pH and soil type. The pH change in heavier textured soils is slower than sandy soils and it is important to anticipate the needs of newly established plants when preparing the soil. A rapid reaction results from application of sulfuric acid or urea sulfuric acid materials.
Blueberries have very superficial root systems and are intolerant of drought or poorly drained soils. For best results, establish the planting on raised beds, incorporating finely ground wood waste. The wood waste may be incorporated with fertilizer and sulfur prior to planting. A surface mulch of wood chips should then be applied around the newly established plants to retain moisture and control weeds. Subsequent annual applications of mulch is advisable and additional smaller amounts of sulfur may also be required. New plantings of blueberries should be kept from producing flowers or fruit for the first three years to allow the plants to develop an adequate plant structure. These trials are only in the fourth year and blueberries remain productive for 15 to 30 years. Much remains to be learned about optimum management of blueberries in these new growing conditions.
Fresh market blueberries are popular and can be a profitable crop during much of the year. One of the most promising aspects of blueberry production in mild coastal areas of California is the prospect of producing fruit for off-season harvest. Traditionally, blueberries for U.S. markets are supplied by offshore production from late September until May. Careful management of cultural practices will enable California growers to expand this promising new crop into new production areas and new market windows. For more information, contact Mark Gaskell, farm advisor, UC Cooperative Extension, 624 West Foster Rd., Santa Maria, CA 93455; (805) 934-6240; e-mail mlgaskell@ucdavis.edu.
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