Growers in the Mid-Atlantic, Appalachian, Southern areas of the East and Midwest, and Pacific areas where winter temperatures do not generally fall below minus -10°F could consider planting a class of blueberries that many growers have not tried — Southern highbush. These hybrids, with genetics from both Northern highbush and native Southern rabbiteye, are untried by most growers in these regions.
Although there are many varieties of Southern highbush, including an abundance of recent introductions over the Southeast and warmer areas of the Midwest, most are winter-hardy only in warmer climates south of our Mid-Atlantic and Appalachian areas.
Consider Chilling Requirements
Lower-chill varieties require fewer chilling hours to maintain dormancy, so plants will resume growth too early in the spring in our region, where buds and blooms are more likely to be lost to freezes and early spring frosts. Growers in our region need to carefully select only those high-chill varieties of Southern highbush that can withstand our colder winters and remain dormant through late winter and early spring.
Nurseries that offer at least four varieties of higher-chill Southern highbush plants are rare, such as Boston Mountain Nurseries in Arkansas. DeGrandchamp’s Nursery in Michigan offers a couple of these varieties, but remember, nurseries offer what growers want, and as more growers try these varieties, more will likely become available based on market demand.
Two varieties should be interplanted for optimum pollination, and the Southern highbush type is pollination-compatible with Northern highbush varieties if you wish to try just one Southern highbush variety.
As our summers get hotter and often drier, these hybrids will provide more tolerance to heat and drought compared to Northern highbush varieties. Also, they withstand plant stress between drip irrigations when busy growers are pushed to keep on a more frequent irrigation schedule in hot, dry weather.
My commercial growing observations here have been with the ‘Ozark Blue’ Southern highbush variety until now. For the past 18 years we have noted that it blooms a bit later than many Northern highbush varieties and has an extended bloom and harvest season with large, tasty berries. I consider it the standard against which to judge other Southern highbush high-chill varieties.
My Own Variety Trial
In my retirement, my plantings now are limited to home garden plots. In November, I planted of four of these winter-hardy hybrids needing at least 600-800 chilling hours below 45°F — ‘Legacy,’ ‘Sweetheart,’ ‘Pamlico,’ and ‘Ozark Blue.’
The ‘Legacy’ variety was bred by the New Jersey Agricultural Research Station and Rutgers University back in 1993. Ripening in that area is in mid-season, close behind ‘Bluecrop,’ a Northern highbush. Berries are medium-large, very high flavor, and hold well on the plants. Plants are upright, vigorous, and provide consistently high yields. ‘Legacy’ also shows resistance to mummy berry and anthracnose.
‘Sweetheart’ is a newer high-chill Southern highbush variety released by USDA in 2010, with early ripening fruit similar to the ‘Patriot’ variety, and just behind ‘Duke.’ Berries are large and high-flavored. Plants are vigorous and fast-growing, and may re-bloom in late summer to produce a second very small crop in some years; it is considered self-pollinating.
‘Pamlico’ is also an early season ripening Southern highbush variety, introduced by North Carolina State University’s Dr. Jim Ballington and colleagues in 2003 at the Castle Hayne Horticultural Research Station. Fruit is considered medium-sized with good flavor and firmness, suitable for hand or machine harvest. Plants are vigorous and resistant to blueberry stem blight.
‘Ozark Blue’ was developed and released in 1996 by Arkansas fruit breeders Drs. John Clark and Jim Moore in cooperation with Dr. Arlen Draper at USDA-Beltsville, MD. ‘Ozark Blue’ was developed and tested in a climate and latitude similar to our region. Observing this variety through all sorts of weather and seasons, with no two consecutive seasons ever alike, I have been very favorably impressed with ‘Ozark Blue.’ With its hardiness, plant vigor, growth rate, upright and fast plant growth early into production, along with its larger berries of intense flavor, it deserves planting by more growers!
‘Ozark Blue’ has provided us with consistent yields even in years when other varieties have been damaged by late frosts and/or freezes. It ripens just after ‘Bluecrop’ in mid-season, and it picks for several weeks. ‘Ozark Blue’ can bring joy to pick-your-own customers and growers, as well as those producing for local markets and fresh market packers.
I look forward to being able to compare these high-chill Southern highbush varieties side-by-side!