NC State Extension Publications

General

The Southern region of the United States encompasses a range of climates, due to elevations that start at sea level and reach 3,000 feet. This wide range of climates enables growers to produce raspberries in the cooler regions and blackberries in the warmer regions from June through October. Consult Tables 2 and 3 to determine the best cultivars for your farm and marketing strategy.

Sites that are elevated above the surrounding terrain offer some natural protection from radiation frosts and disease. Frosts and fogs tend to settle in lower areas first. Planting on top of a hill in a windy area may be undesirable due to the possibility of plant and fruit damage from desiccation and cane breakage. A gentle, uniform slope may be most desirable for fruit crops. Steep slopes (in excess of 12 to 15 degrees) present challenges in establishing and maintaining the planting and can be hazardous when operating equipment on them. Soils on south-facing slopes tend to be hotter, dryer, thinner, and have a lower organic matter content than those on north to northeastern-facing slopes. The potential for winter injury and frost damage tends to be higher on south-facing slopes as well. While fruit may ripen earlier on a south-facing slope, the potential for crop loss is higher. Crops on slopes with an eastern aspect dry off quicker in mornings due to earlier sunlight exposure. Northern facing slopes will produce fruit later in the season and fruit will be less likely to be injured by spring frosts (Figure 6).

Both blackberries and raspberries grow best with full sun and a well-drained soil. The most suitable soils are high in organic matter (2 percent) and have a pH of 6.0 to 6.5. Sandy loam or loam soils are best. Blackberries and raspberries can be grown in sandy soils if a good irrigation system is used. In general, their root systems do not tolerate wet soils. Avoid clayey, poorly drained soils in locations with high water tables or in areas prone to flooding. Use of raised beds can, in part, compensate for a periodically wet site.

Raspberries are susceptible to the verticillium pathogen, and sites with a history of the disease should be avoided. However, verticillium is not a major soil pathogen in the southern United States. Likewise, phytophthora root rot is a common problem for raspberries in other regions. Due to limited production of this crop in the region, phytophthora is not a major concern at this time. However, in western North Carolina, the P. cinnamomi species is a major cause of disease in Fraser Fir trees. Although P. cinnamomi is not known to infect Rubus, it is a highly virulent disease and could become a problem in areas that are infested.

Avoid sites where strong hot summer winds or cold winter winds prevail. Hot summer winds can dry the fruit, cause sunscald, and increase plants’ water needs. In addition, fruit size and plant growth will be compromised. Cold winter winds can cause winter injury, which often results in cane breakage, cane dieback, or both. Windbreaks can be used to reduce air movement if you suspect it may damage your crop. Keep in mind, however, that good air circulation minimizes disease problems.

New caneberry plantings should be isolated as much as possible from wild raspberry and blackberry plants, which harbor diseases and insects that can devastate your crop. New plantings should be at least 100 to 200 yards from wild caneberries. Additional site recommendations related to insects and diseases can be found in the Southeast Regional Caneberries Integrated Management Guide, located on the Southern Region Small Fruits Consortium’s IPM/Production Guides webpage.

Blackberry Raspberry
Blackberries grow best in warm, temperate regions and are generally considered less hardy than raspberries. The plants flower from March in southern Georgia to May in the mountains, and bloom over a long period. Because blackberries flower late, damage to flowers from spring frosts and freezes is seldom a problem in the piedmont and coastal plain. In the mountain areas where the winters are more severe, the use of hardy cultivars and planting of blackberries on hillsides above frost pockets will help to avoid damage to the canes from the cold. In general, blackberries are recommended for areas where winter temperatures stay above 10°F. Raspberry plants perform best where the growing season is long and summer temperatures are mild. They also grow best where winters are uniformly cool and long enough to satisfy their chilling requirement. These conditions are not typical of most areas in the southern United States. With careful selection of cultivars, however, coupled with good cultural practices, they can be grown successfully despite the odds. The best growing conditions in the southern United States exist in the high elevations of the Appalachian Mountains. The summer temperatures are not too hot, and the winter temperatures do not fluctuate as much as in the lower elevations.

Figure 6.

Figure 6. This diagram shows the expected conditions that can be found with sites facing principal directions.

Row Orientation

Wherever possible, orient rows north to south. Fruits and foliage will receive more uniform sunlight exposure throughout the day with this orientation than with other row directions, and problems with sunscald, which often occurs on the south side of east-west oriented rows, will be lessened. However, taking into account that the desired floor management system for caneberry plantings consists of a 4-foot wide clean strip in the row plus a closely mowed sod strip between rows, rows on sloping ground should be oriented perpendicular to the direction of the slope. This orientation allows for better erosion control, simpler irrigation designs, and greater precision in pesticide applications than working up and down hills. In the piedmont and mountain regions, fescue is an excellent choice for a perennial ground cover between rows. Planting on a contour, while desirable in other circumstances, presents special problems for constructing and maintaining trellises. Instead, consider planting straight rows, stopping the row when the slope within it becomes too great and restarting the row in a slightly different direction. Leaving a gap between the ends of the trellises allows for air drainage out of the field and provides turning room within the planting.

Authors:

Extension Specialist (Small Fruits)
Horticultural Science
Professor
University of Arkansas
Professor
University of Tennessee

Publication date: Oct. 30, 2015
Last updated: Aug. 23, 2017
AG-697

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