Blackberries, like raspberries, are a very easy berry to grow. Once this native berry is ripe, get ready for an abundant harvest, picking every couple of days! Here’s how to grow and harvest blackberries in your backyard.
Basically, there are three types of blackberries:
Erect thorny blackberries
Erect thornless blackberries
Trailing thornless blackberries
Erect blackberries are bushes that support themselves, while the trailing blackberries have long canes that must be trellised for support.
All blackberries are perennials; the roots survive year after year. However, the top of the plant above the soil is what we call biennial. This means that the canes grow vegetatively for a year, bear fruit the next year, and then die. However, every year the plant sends up new canes to replace those that died! For a great fruit harvest and to avoid a messy plant, pruning is important. (Learn about proper pruning techniques below.)
Make sure you plant your blackberries far away from wild blackberries, which may carry (plant) diseases that could weaken your own plants.
How to Plant Blackberries
For semi-erect cultivars, space plants 5 to 6 feet apart. Space erect cultivars 3 feet apart. Space trailing varieties 5 to 8 feet apart. Space rows about 8 feet apart.
Plant shallowly: about one inch deeper than they were grown in the nursery.
How to Care for Blackberries
Mulchingis important throughout the season to conserve moisture and suffocate weeds. Keep a thick layer of mulch surrounding plants at all times.
Blackberries require plenty of moisture, especially when growing and ripening. Ensure plants receive one inch of water per week and more in hot temperatures.
Blackberries benefit from fertilizing in early spring with an all-purpose fertilizer such as 10-10-10, or a 16-16-8.
Trellis Trailing Blackberries
As mentioned above, trailing blackberries need a trellis or support. Explore a two-wire system, running a top wire at five to six feet with a second line 18 inches below the top wire. After the first year, there will be fruiting floricanes along the wires. Train the new primocanes into a narrow row below the fruiting canes. Directing all canes in one direction may make it simpler.
We have provided detailed pruning information below, but do not be scared. The main idea is to simply remove the old canes that already bore fruit and let new ones take their place.
Trailing blackberries: After the fruit harvest period, the old fruiting (floricanes) are removed to the ground. However, unless there is a lot of disease, it’s best to delay removing the old fruiting canes until they have died back considerably. This allows the dying canes to move nutrients back into the crown and roots. After you remove the old fruiting canes, you may train the primocanes up on the wires. Work with one or two canes at a time in a spiral around the trellis wires. Canes from adjacent plants may overlap a little. No pruning of primocanes is necessary.
In areas with low winter temperatures, it’s fine to leave the primocanes on the ground for the winter, where they could be mulched for winter protection. In the spring, after the danger of extreme cold has passed, train the old primocanes (now considered floricanes) up on the wires. Avoid working with the canes in cold weather, as they are more prone to breaking.
Erect blackberries produce stiff, shorter canes that come from the crown and from root suckering (often forming a hedgerow).
Erect blackberries benefit from summer pruning. Remove the top one to two inches of new primocanes when they are four feet tall. This causes the canes to branch, increasing next year’s yields. Plants will require several pruning sessions to tip each cane as it reaches the four-foot height. Primocanes (suckers) that grow outside the hedgerow should be regularly removed.
In the winter, remove the dead floricanes (old fruiting canes) from the hedgerow. Also, shorten the lateral branches to about 1½ to 2½ feet.
If you have primocane-fruiting erect blackberries, which are harvested in late summer/early autumn, cut all canes to the ground in the late winter (after the fall crop). In the summer, when the primocanes are 3½ feet tall, remove the top 6 inches. The primocanes will branch, thereby producing larger yields in the fall.
If you have semi-erect blackberries, they are easier to manage on a Double T Trellis. Install four-foot cross arms at the top of a six-foot post. Install a three-foot cross arm about two feet below the top line. String high-tensile wire down the rows, connecting to the cross arms.
Semi-erect berries need to be pruned in the summer. When the primocanes are five feet tall, remove the top two inches to encourage branching. Several pruning sessions will be required as canes reach the appropriate height. In the winter, remove the dead floricanes (old fruiting canes). Spread the primocanes (new floricanes) out along the trellis. Canes do not need to be shortened. However, they can be if they are difficult to train.
Here are some favorite blackberry varieties to investigate, but be sure to ask about varieties that fit your growing zone.
Erect Thornless: ‘Navaho,’ ‘Arapaho’
Erect Thorny: ‘Cherokee,’ ‘Brazos,’ ‘Shawnee,’ and ‘Cheyenne’
Semi-erect Thornless: ‘Black Satin’
How to Harvest Blackberries
Pick only berries that are fully black. Mature berries are plump yet firm, a deep black color, and pull freely from the plant without a yank. Berries do not ripen after being picked.
Once blackberries start to ripen, they must be picked often—every couple of days.
When picking, keep the central plug within the fruit (unlike raspberries).
Harvest during the cooler parts of the day. Once picked, place berries in the shade and refrigerate as soon as possible.
How to Store Blackberries
Blackberries are highly perishable and will only last a few days once harvested, even with refrigeration.
Although fresh fruit is always best, blackberries can be stored by canning, preserving, or freezing. Techniques used for freezing blueberries can also be used on blackberries.
Wit and Wisdom
Blackberries, raspberries, and strawberries are very high in ellagic acid, which is an antioxidant that acts as a scavenger, helping to make potential cancer-causing chemicals inactive. Ellagic acid reduces the genetic damage caused by carcinogens like tobacco smoke and air pollution. Blackberries also contain other antioxidants that can help lower cholesterol and ward off cardiovascular disease.
If your plant is suffering from the blackberry disease known as Raspberry Bushy Dwarf virus, the leaves will have some bright yellow on them, and the leaves of the fruiting vines may have a bleached look in the summer. The disease known as Blackberry Calico will cause faint yellow blotches on the leaves of the plant.