Homegrown fruit always beats market fruit for freshness and taste, but not everyone has the space to grow a fruit tree or a melon vine. For that reason, berries are the gateway fruit for many gardeners, and none are easier to grow in the home garden than the blackberry. As native North American fruiting shrubs that can typically be harvested from June to August, blackberries are primed to grow in your yard with little extra maintenance. All you need to grow summer blackberries for your pies, jams, and smoothies is a spot with full sun and a good supply of soil amendments such as compost or leaf mold.
Blackberries are sold as dormant bare roots or as potted plants. They are best planted when the canes are dormant—generally in early spring. If you have the patience to grow blackberries from seed, plant them in the ground in the fall. Planted from seeds, blackberry canes generally will begin producing meaningful quantities of fruit in their second full year of growth.
|Botanical Name||Rubus Fruticosus|
|Sun Exposure||Full sun|
|Soil Type||Rich, well-drained loam|
|Soil pH||Slightly acidic to neutral (5.5 to 7.0)|
|Native Area||North America, especially the Pacific Northwest|
|Toxicity||All parts are non-toxic|
How to Plant Blackberries
As members of the Rosaceae family, the cultivation of blackberries resembles that of rose bushes. Fortunately, blackberries are closer to wild roses in their ease of care than they are to a hybrid tea rose. Blackberries will tolerate many growing conditions, but the harvest of a struggling blackberry plant will be disappointing compared to the harvest of a pampered plant. Plenty of sunshine, regular irrigation, and rich loamy soil will give plants the energy and nutrients they need to yield sweet, jumbo blackberries.
Plants should be spaced 5 to 6 feet apart; if planting in rows, space the rows 5 to 8 feet apart. If necessary, amend the soil before planting so it is rich, well-drained, and slightly acidic. Blackberries should be planted relatively shallow—about 1 inch deeper than they were growing in the nursery pot.
Trailing varieties of blackberries should have a trellis or other form of support to secure the canes.
Sites with full sun are best for productive blackberry bushes. Some afternoon shade is tolerated, especially in areas with hot summers.
Careful site selection will ensure a long life for your blackberries, which usually live for about a decade with proper care. The ideal soil is slightly acidic with good drainage; these plants do not do well in clay soil. An elevated site or raised beds will not only help drainage but will also prevent late spring frosts from damaging flower buds. Remove all weeds that might draw nutrients or water away from your blackberries, as their shallow roots are susceptible to this competition.
Keep a good layer of mulch over the root zone at all times. This will feed the plants, conserve water moisture, and keep weeds down.
Blackberries need moderate amounts of water, around 1 inch per week provided either by rainfall or from ground-level irrigation. Blackberries do not fare well in wet soils.
Temperature and Humidity
Blackberries require a period of cold dormancy to germinate, but because of their shallow root systems, they don't do well in areas where temperatures go below zero degrees routinely. Zones 5 to 8 provide the best environment for blackberries. Cold winter temperatures combined with wet spring soils may lead to plant death. The reverse environment of hot, dry winds is also unfavorable for blackberry growing and may result in stunted, seedy fruits.
Fertilize your blackberries in the spring when plants are emerging from dormancy, using a balanced 10-10-10 formula. Fertilize plants again in the fall with an application of manure and compost, which will also suppress weeds and improve soil tilth.
Blackberries are usually categorized according to their growth habit:
- Erect thorny blackberries grow upright and don't require support for the canes. They have very sharp spines on the canes—sharp enough to tear clothing.
- Erect thornless blackberries are similar, but have canes without the prickly thorns. They, too, require no trellis supports.
- Trailing thornless blackberries have sprawling canes that require a trellis or system of wires to hold them up above the ground.
'Shawnee' is resistant to cold, and has self-supporting thorny canes. 'Natchez' is thornless and erect, and will form a hedgerow as it spreads by suckers. Semi-erect thornless varieties like 'Chester' and 'Triple Crown' grow as a clump, and benefit from a trellis. Varieties like 'Prime-Ark Traveler' produce fruit on new and old canes throughout the season.
Blackberries vs. Raspberries
Both blackberries and raspberries belong to the Rubus genus. Blackberry and raspberry plants look very similar—both featuring thorny canes and compound leaves with toothed edges in groups of three or five. One key difference between the fruits of blackberries and raspberries is the way the fruits are formed. The tiny globes of the fruits, called drupelets, are attached to a white core in blackberries. Raspberries, including black raspberries, form drupelets with a hollow core.
Because they are highly perishable, it's important to follow the development of your ripening blackberries carefully. Immature blackberries start out green, then transition to red before maturing to a deep, glossy black. Blackberries do not continue to ripen after harvest, so pick the berries only after they have turned completely black. Berries last about seven days in the refrigerator after harvest.
Blackberry roots are perennial but the canes are biennial. This means that second-year canes that have produced their fruit need to be trimmed away after harvesting.
For an established shrub, new canes that haven't yet fruited should be tip-pruned to about 3 feet in summer. This will cause the new canes to branch out, maximizing the fruit produced. Once these canes produce fruit, they should be removed to the ground immediately after the fruit harvest.
In early spring before new growth has started, remove any canes damaged by winter, and thin out the remaining canes to the four or five strongest canes.
It's easy to propagate blackberry plants from stem cuttings. Cut a 4-inch piece from the end of the stem in late spring when temperatures are mild and rainfall is plenty. Plant it in the soil, and keep it moist. Roots will form in two to four weeks. These newly started plants can be planted in the fall, or you can keep them in a sheltered location and plant them the following spring.
Common Pests and Diseases
Blackberries are prone to anthracnose, stem blight, and crown gall. Prevent disease by purchasing disease-free plant stock from reputable nurseries, and planting your blackberries away from areas with wild brambles, which may carry these diseases.
Insect pests include stink bugs and raspberry crown borers. Keeping your plants healthy and vigorous will make them less attractive to insect attack.
Blackberries are sometimes afflicted by viral diseases. Raspberry bushy dwarf virus and blackberry calico virus both cause bright yellow splotches to appear on leaves. Affected plants will need to be removed and destroyed.
How to Grow Blackberries in Pots
When growing blackberries in containers, choose a compact cultivar like Baby Cakes that does not need pruning. Choose large containers that hold at least five gallons of soil to prevent drying out.