Blackberries
Rubra fruticosus and Rubra subg. Rubrus. ROSACEAE.
Planting, Growing, and Harvesting Blackberries
You’ll find everything you need to know to plant and grow blackberry in the accompanying table’s tabs:
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- How many blackberries to plant
- Growing conditions for blackberries
- When to plant blackberries
- How to plant blackberries
- Watering, fertilizing, and pruning blackberries
- Companion plantings for blackberries
- How to harvest, store, and use blackberries
Growing Blackberries
Blackberries are cool-season perennials. Most have trailing, canelike vines to 8 ft. (2.4 m), with invasive root runners, and bear cup-shaped berries in shades of red and black.
Besides trailing vines, other varieties include erect and semi-erect plants. All have both thorn-bearing and thornless cultivars. Thornless varieties tend to yield fewer berries.
There are wild and domesticated cultivars, hybrids, and cultivars. These include the most popular blackberry varieties, boysenberry, loganberry, marionberry, and ollalieberry. Choose cultivars known to be successful in your region.
Blackberry Plant and Care Guide
How Much to Plant
Allow 4–6 plants per household member. For jams or jellies, allow 12–16 plants, yielding 4–5 qts. (4.4–5.5 l).
How to Plant Seed
To grow blackberry starts from seed, allow berries to mature fully on canes, pick, and set aside in a warm, dry place to dry. Extract seeds only after pulp completely dries.
Sow seed shallowly in sterile sandy loam soil mixture. Keep moist. The seed will germinate in 12–14 days.
Transplant to rearing containers or to garden soil when seedlings reach 5 in. (25 cm) tall. Seedlings require at least three seasons before they begin to bear fruit.
How to Plant
Cold-Winter Climates: Set out bare-root divisions in partial shade in early spring when soil warms to 35–55°F (2–13°C).
Mild-Winter Climates: In early spring or autumn.
Erect Varieties: Set out bare-root divisions in a trench 6 in. (15 cm) deep, 30 in. (75 cm) apart, in rows 10 ft. (3 m) apart.
Trailing Varieties: Set out bare-root divisions 1 ft. (30 cm) deep, 5–8 ft. (1.5–2.4 m) apart, in rows 10 ft. (3 m) apart.
Blackberries may become invasive; install root-guard barriers, at least 18 in. (45 cm) deep, to prevent roots from spreading beyond the bed, as well as trellises or support wires, 6–8 ft. (1.8–2.4 m) tall.
Cover roots with 1 in. (25 mm) of soil until they sprout, then gradually backfill as new canes grow until the trench is filled.
Best Conditions for Growth
Growing temperature: 55–80°F (13–27°C). Plant Hardiness Zone tolerance vary by variety (Typically: erect: zones 3–9; trailing: 4–10). Best in mild climates with maximum of 5 hours of direct sun daily.
Soil Type and Fertility
Moist, well-drained soil. Fertility: Rich. 5.5–6.8 pH. Prepare soil at least 2 ft. (60 cm) deep.
Proper Care
Moderate. Keep evenly moist until fruit matures; reduce watering thereafter to limit cane growth. Fertilize quarterly with acidic 10–10–10 formula supplemented with garden sulfur. Mulch. Cultivate. Tie trailing varieties onto wire supports. Prune away old canes after fruiting ends, leaving new canes to produce fruit the following season.
Pairing Recommendations
Asparagus and other berry, cane, and vine plants.
Maturity, Picking and Gathering
Late spring and summer of second season, then annually. Pick berries when full colored, sweet, plump, and easily pulled from canes; avoid washing. Regular picking encourages production of new flowers and a longer harvest.
How to Store and Preserve
Fresh in vegetable keeper of refrigerator for 1–2 weeks; frozen whole or as pie fillings, 1 year; preserved as jams or jellies, 3 years.