How to Grow Blackberries

Pick the right type for your region

Blackberries are sorted three ways. Growth habit can be erect, semi-erect or trailing. Canes are thorny or thornless. Fruiting is either floricane or primocane. Floricane types fruit on second-year canes in early summer. Primocane types, also sold as everbearing, also fruit on the tips of first-year canes in late summer and fall.

Blackberries handle heat better than raspberries, which is why they grow across most of the South. Their weak point is winter cold. University of Tennessee Extension puts them at hardy to only about 0 to -10°F and says thornless types may be less hardy still. NC State notes that its recommended list struggles wherever temperatures fall below 10°F. Chill needs also matter. Cultivars range from about 200 to 900 chill hours, and Tennessee warns that low-chill cultivars (under 400 hours) bloom early and risk frost damage in colder, higher sites.

Cultivars extension services recommend:

• North Carolina and the Southeast (NC State): ‘Natchez’ (early), ‘Ouachita’ and ‘Osage’ (mid), Sweet-Ark ‘Caddo’ and ‘Ponca’ (early), and ‘Von’ (mid to late). NC State suggests treating ‘Prime-Ark Freedom’ and ‘Prime-Ark Traveler’ as single summer crops because their fall crop is unreliable there.
• Mississippi (MSU): ‘Ouachita’, ‘Natchez’, ‘Osage’, ‘Kiowa’, ‘Caddo’, ‘Ponca’ and ‘Sweetie Pie’, a USDA release that tolerates heat well and resists rosette.
• Maryland and the Mid-Atlantic (UMD): ‘Eclipse’, ‘Galaxy’, ‘Twilight’, ‘Natchez’, ‘Ouachita’ and the Sweet-Ark and Prime-Ark series, plus trailing ‘Triple Crown’, ‘Chester’ and ‘Hull’.
• Florida (UF/IFAS): ‘Osage’, ‘Ouachita’, ‘Ponca’, ‘Kiowa’ and the Prime-Ark series for North and North Central Florida. ‘Prime-Ark Freedom’ is the one to try in South Florida.
• Texas (Texas A&M): ‘Natchez’ was named a Texas Superstar after statewide trials.
• North central Arizona (University of Arizona): ‘Navaho’ and ‘Choctaw’, erect ‘Brazos’ and ‘Roseborough’, semi-erect ‘Black Satin’ and trailing ‘Olallie’. Arizona says blackberries do best above 2,500 feet.

Hot summers cut short the fall crop on primocane types. Mississippi State says they are not suitable for fall fruit there because of heat during flowering, and NC State says double cropping works best in the western, cooler part of that state.

Site and soil

Choose full sun, 6 to 8 hours or more, with soil that drains well. Blackberry roots do not tolerate wet soil, so build raised beds if water stands after rain. NC State recommends a pH of 5.5 to 6.5 and Mississippi State 6.0 to 6.5. Prepare the bed a year ahead, as NC State advises, by killing perennial weeds and working in organic matter.

Where you plant also affects disease. Keep new plants at least 300 feet from wild brambles, a potential source of disease (University of Maryland). Mississippi State notes that removing wild blackberries helps control rosette. Tennessee advises against sites that recently grew strawberries, potatoes, tomatoes, peppers or eggplant because of soilborne wilt. Buy certified disease-free plants and do not dig up a neighbor’s suckers, which can bring viruses with them (UC IPM).

Planting

Planting time depends on your winter. NC State plants in early spring, several weeks before the last frost. Mississippi State uses late February to early March, Texas A&M mid-January to early February, and UF/IFAS February to April in Florida. UC IPM gives mid-January to March for California. Tissue-culture plants sold in pots may not be hardened to frost, so Maryland advises setting them out after your last frost. Check the dates for your zone above.

1. Space erect and semi-erect plants 3 to 4 feet apart (NC State) and trailing types 6 to 8 feet apart. Allow about 8 feet between rows (Maryland).
2. Keep bare roots moist, spread them in a wide hole, and set the plant about 2 inches deeper than the crown.
3. Cut the tops back to about 6 inches and water well.
4. Hold off on fertilizer for three to four weeks. UF/IFAS cautions that excess fertilizer can burn leaves or even kill plants.

Trellising and training

Put up the trellis in the first year. NC State uses two wires, at 3 and 5 feet. Fan erect and semi-erect canes across the wires as they grow. Weave trailing types back and forth along the wires and do not tip them.

On erect types, pinch the tips of new canes in summer to make them branch. Maryland and Mississippi State tip at 3 to 4 feet, NC State once canes reach the top wire, and Arizona at 3 feet. Vigorous plants may need topping two to four times a season. In winter, shorten the side branches to about 12 to 18 inches. Keep three or four strong new canes per plant. NC State thins to four to eight canes per square yard of row in winter.

Pruning after harvest

Each cane lives two years and dies after it fruits. As soon as harvest ends, cut the old fruiting canes at ground level and remove them from the garden so they don’t harbor disease. Leave no stubs. Then keep tying in the new canes, because they carry next year’s crop.

Primocane types give you two options. To get two crops, prune them like floricane types. For a single late crop, mow every cane to the ground each winter.

Water and fertilizer

Give about 1 inch of water a week during the growing season. NC State estimates about 2 gallons per plant per day while fruit is sizing. Drip irrigation and a mulch of pine straw or wood chips save water and keep weeds down. Arizona advises against overhead sprinklers that wet the foliage.

NC State feeds established plants with 10-10-10 in March, well before bloom, and again after harvest, at about 5 pounds per 100 feet of row. That is roughly 3 to 4 ounces per plant.

Harvest

Blackberries are ripe when the shine fades to a dull black. They pull off easily, and the white core comes with the berry. Shiny black berries are less sweet but keep longer in the refrigerator. Pick every few days, in the cool of the morning, and refrigerate right away. Each cultivar bears for about two to four weeks. In Mississippi and Florida the main crop ripens in May and June.

Common problems

• Rosette (double blossom): a fungal disease that limits blackberries in the Southeast. Thornless cultivars have some tolerance, and removing nearby wild blackberries helps.
• Orange rust: infected plants stay infected. Start with clean stock and propagate only from healthy plants. NC State’s ‘Von’ does not get orange rust (Tennessee).
• Spotted-wing drosophila: small larvae inside ripe berries. Pick often and chill the fruit quickly.
• Cane borers: prune out wilted canes during the season.
• White drupelets: sunscald in hot, bright, dry weather. Lightly affected berries are still fine to eat.