How To Grow And Care For Blackberries

In the South, blackberries hold an honored place not just on our tables but also in our memories. For many of us, one taste of a blackberry cobbler instantly brings back thoughts of childhood summers spent picking berries. Blackberries are some of the first fruits of the season. White flowers in spring are followed by clusters of fruit that turn from green to red to purple before ripening to black.

Blackberries include several species, a collection of wild fruit brambles that scramble along the ground or create tall thickets in the wild. Cultivated blackberries are usually erect or trellised and have larger, sweeter, and less seedy fruit. There are even varieties without thorns so that you can gather berries without covering yourself in scratches. Find a sunny corner in your backyard and plant one of these delicious cultivars for a summertime treat.

Blackberry Care

Blackberries like a sunny spot with well-drained, fertile soil. Plant in fall or winter, spacing them 3 to 4 feet apart. Mulch with pine straw or shredded pine bark to conserve moisture and discourage weeds. Prune old canes right after fruiting to encourage new canes and discourage diseases. Buy plants at a local nursery, or order from your favorite online retailer.

Light

Cultivated blackberries require full sun for good flowering and fruiting. Many types of blackberries tolerate partial sun as well, but this usually results in fewer and slower-ripening berries. Try to provide at least six hours of direct sunlight a day.

Soil

Blackberries require slightly acidic, well-drained, organically rich soil in order to thrive. The plants do best in loam or sandy loam soil. Loosen the soil to a foot deep and add compost or aged manure to improve drainage if needed. Raise the soil level higher if poor drainage is a problem.

Water

Though they are drought-tolerant plants, blackberries will produce the best fruit if they receive 1-2 inches of water a week while berries are present. Water deeply a couple of times a week when plants are first getting established and during hot, dry weather. Mulch around the plants to conserve moisture. Watering is rarely necessary in winter or while the plant isn't fruiting.

Temperature And Humidity

Most blackberries can be grown in USDA Plant Hardiness Zones 5-9. There are cultivars bred to survive harsher winters and others that will fruit in warmer climates. Blackberry plants require chill hours in winter in order to set fruit—they must spend some amount of time below 45ºF. How much depends on the type you grow. If you live in the Coastal South, look for blackberries that are recommended for Zone 9. Blackberry plants will shrug off the summer heat, but harvested fruit should be refrigerated immediately so it will last.

Fertilizer

Many home gardeners find that a thick layer of mulch provides all the fertilizer their blackberries need. Add a couple of inches each year as the mulch breaks down and enriches the soil. If you do choose to fertilize, wait until the second year. Use a balanced 10-10-10 fertilizer in late spring and apply 1/4 pound, or about 1/2 cup, of fertilizer in a foot-wide circle around each plant.

Types Of Blackberries

University of Arkansas horticulturists have developed new, improved selections of blackberries over the decades. More recent releases are thornless and have better disease resistance. These blackberries are self-pollinating, so you can choose to plant just one of these cultivars:

• 'Kiowa' is an older thorny variety that requires just 200 chill hours, making it a good choice for the Coastal South. The fruit is very large, but plants are susceptible to rosette disease.
• 'Ouachita' is an erect thornless blackberry with large fruit that requires lower chill hours than many. 'Ouachita' is resistant to rosette disease.
  
• 'Osage' is another thornless blackberry with fewer chill hours required. The medium-sized fruit ripens slightly earlier and is noted for its sweet flavor.
• 'Arapaho' has medium-sized fruit and is the earliest ripening erect thornless variety. The yields are lower, but it is resistant to orange rust and rosette diseases.
• 'Natchez' is a semierect thornless blackberry that is best grown on a trellis or fence. The early ripening, elongated fruit has excellent flavor. 'Natchez' has strong disease resistance.
• 'Navaho' is an erect, thornless blackberry with very sweet, medium-sized fruit and requires more chill hours. The yield is lower, but it has a long ripening season. 'Navaho' is tolerant of rosette but susceptible to orange rust.
• 'Apache' is an erect thornless blackberry with higher chill hours. It has the largest fruit and highest yield of the Arkansas thornless blackberries. 'Apache' is resistant to orange rust and rosette.
• The newer 'Prime-Ark' series of blackberries stand out for their ability to produce fruit on "primocanes," or the soft, green canes in their first year of growth.
• 'Chester' is a cold-hardy, semi-erect, thornless blackberry that came from breeding programs in Illinois, Ohio, and Maryland. The medium-sized fruit is ready for picking in late summer.

Pruning

Most blackberry plants produce primocanes that sprout one year, produce fruit the next year as "floricanes," and then die back. Dead floricanes should be cut to the ground each winter. In summer, you can cut the tip of each new green primocane once it reaches about three feet tall. This will encourage the plant to produce lateral branches and grow bushier. If you choose not to prune your floricanes, use a trellis to support the tall, lanky growth.

Propagating Blackberries

Cultivars that are not patented can be propagated in the home garden. The easiest and fastest way to propagate blackberries is by transplanting the suckers that sprout up from the roots. This is preferable to trying to grow blackberries from seed, which requires months of cold treatment and often does not produce a plant with the same characteristics or fruit. To propagate your suckers, gently clear away the soil to find the roots. Use a sharp knife or pruners to cut the sucker from where it is attached to the mother plant, keeping as much of the sucker's root system intact as possible. Replant the sucker at the same depth in a new location. Water deeply, keeping the soil moist while the plant is getting established.

Common Pests & Plant Diseases

Choose resistant cultivars to avoid two of the most significant fungal diseases that afflict blackberries: orange rust, which appears as bright orange pustules on the leaves and prevents blooming, and rosette or double blossom disease, which distorts flowers and branches and prevents fruiting. Plants with orange rust must be burned or disposed of in the trash. Rosette can be controlled with heavy pruning of diseased stems in early spring followed by repeated spraying with fungicide from bud break until flower petals fall.

Keeping wild brambles off your property can also help reduce the incidence of disease. They could harbor any of the following:

• Anthracnose: This fungus causes small, bulls-eye spots on canes and leaves; spray young canes and budding blossoms with fungicide; remove floricanes immediately after harvest and dispose of them in the trash
• Botrytis fruit rot and cane blight: fungus causes white lesions on cane and shrivels up flowers; spores appear on fruit; avoid fertilizing and overhead watering; spray with fungicide
• Cane and leaf rust: small yellow pustules appear on underside of leaves; remove diseased canes immediately after harvest; spray with fungicide at bud break
• Crown gall: bacteria causes large, brown, tumor-like growths to appear on canes; remove and destroy affected plants and avoid replanting in the same spot
• Phytophthora root rot: Canes may die rapidly or slowly yellow, wilt, and die; remove and destroy affected plants; treat surrounding plants with fungicide
• Septoria leaf spot: small, light lesions with brown margins appear on leaves; may require repeated sprays with fungicide

Blackberry plants can also be attacked by a number of insect pests, but the only serious one is the blackberry crown borer. The adult moth has black and yellow bands and looks much like a yellow jacket. The off-white larvae pupate in the crown of the plant. Look for wilting or dying canes, sawdust at the base of canes, and tunnels in canes. Dig out affected canes and roots in the fall and burn them or throw them in the trash. Spray plants with an insecticide containing permethrin or rotenone in the fall before larvae overwinter in the crowns, and again in spring when the larvae become active.

Another borer, the red necked cane borer, is a small metallic black beetle with a reddish neck. The larvae tunnel into canes, causing brown galls on the stems an inch or two long. Simply remove and dispose of infested canes during the winter.

Other insects cause less damage but can transmit disease to your plants. To keep their numbers from getting out of control, you can pick off large insects and dispose of them in soapy water, spray off aphids and spider mites with a strong stream of water, or use insecticidal soap while the plant is not flowering.

How To Get Blackberries To Bloom

If your blackberries are not blooming, look for signs of disease as described above and treat any problems. Remember that most blackberry canes bloom in their second year of growth, so you may not see any flowers in the first year you planted. If your plants are in a shady spot, transplant them to where they will receive at least six hours of sunlight a day.

Common Problems With Blackberries

Sometimes blackberries yield little fruit, destroying any plans you had for homemade blackberry jelly. While disappointing, this can usually be remedied by taking better care of your plants. Clear away any weeds that are competing with your plants and put down a thick layer of mulch. First spread a layer of organic material such as compost if your soil has poor fertility. Prune away any weak and spindly canes. Water the plants during hot, dry weather. And finally, bird netting will save more of your berries from birds and squirrels.