Blueberries a tasty garden addition

Blueberries can be grown in various Hawaii climates. Southern highbush blueberries have flowered and fruited at as low as the 250-foot elevation, even without a companion plant for cross-pollination, and they are relatively easy and very rewarding plants.

Southern highbush blueberry is a complex hybrid of the Vaccinium species. It differs from the northern highbush mainly in that it doesn’t need as cold a temperature before it will flower. Blueberries, native to North America, Southeast Asia and Central and South America, actually belong to the same genus as our native ohelo plants. Because they can trace some of their lineage to the tropics, they offer an opportunity for fruit production even in Hawaii’s warm climate.

Question: What kind of blueberries should I grow?

Answer: The University of Hawaii College of Tropical Agriculture and Human Resources is testing various southern highbush varieties, including emerald, jewel, sharpblue, misty, sunshine blue, Biloxi and sapphire. Most of these varieties have successfully flowered and fruited at low elevations. Contact your local master gardener or extension agent to find the right variety for your area — Hawaii’s unique microclimates can have advantages for growing blueberries.

Q: Do they require full sun? How much fertilizer do I add?

A: Blueberries grow best in full sun but will tolerate partial shade. The plants have fibrous shallow roots with no main taproot. Their ideal soil is acidic (pH 4.0-5.0), high in organic matter and well drained. Raised beds will help with any drainage problems associated with heavy soils.

For home gardens, plant four inches apart in every direction to give them room to grow. Maintaining a constant water supply is important. A general fertilizer recommendation is to apply one ounce of a 1:1:1 (13-13-13) fertilizer spread evenly over a 2-foot diameter and repeat this application every other month, depending on the size and maturity of your plant.

Q: Can I grow blueberries in containers?

A: For the lanai or small-space gardener, blueberries grow well in containers. We use a mix of equal measures of peat to perlite to provide a low pH and well-drained media. Daily watering is highly recommended, as peat tends to be difficult to re-wet once it dries. A 2- to 3-year-old plant will probably need to be repotted into a 5- or 7-gallon container to reduce the chances of top-heaviness and tipping. Pruning to remove whips and/or training to foster large cane development is also recommended. Flowering usually occurs on the upper parts of the current growth.

Q: Do I have to spend a lot of time with pest problems?

A: The main pests you are likely to encounter will be birds, mice, blueberry rust disease and Chinese rose beetles. Bird netting or protective shelters will fend off birds and mice. Blueberry rust is a disease caused by a fungal pathogen. Growing plants under cover and in a well-ventilated area appears to greatly reduce the severity of this disease. Plants originally infected with rust have shown no symptoms once they were removed from the field to a greenhouse. Unfortunately, there are no known varieties of blueberries that are resistant to this disease.

Chinese rose beetles are strong fliers and feed on leaves during the evening. Various strategies such as repellents and barriers have been successful in minimizing leaf damage; ask at your local garden-supply store for rose-beetle repellents.

Q: Why are blueberries so popular?

A: Blueberries are an ideal snack because they’re tasty and have positive health effects linked to their high content of phytochemicals, or plant-derived chemicals. These can be broken down into flavonoid and nonflavonoid compounds, but evidence suggests the greatest health effects are obtained by eating the whole berry instead of any single component. So, why not grow your own?

This article is based on an upcoming publication by Randall Hamasaki, Stuart Nakamoto and Andrew Kawabata, researchers with the University of Hawaii College of Tropical Agriculture and Human Resources. For information on the Master Gardener program, visit www.ctahr.hawaii.edu/uhmg.