How to grow Blackberry

Where to plant

Choose a sunny, easy to reach spot with plenty of room, and prepare it a year ahead if you can by clearing perennial weeds. Blackberries need well drained soil, ideally a sandy loam with a pH of 5.5 to 6.5; on poorly drained ground, plant in a raised bed. Avoid sites where wild brambles grow nearby, as they carry diseases.

Erect, thornless Arkansas varieties suit the South, Texas, the Mid-South, the Mid-Atlantic and the southern Midwest. Trailing types such as Marion and Boysen suit the Pacific Northwest and Northern California. Northern gardens need hardy varieties, and the Northern Plains and most of Alaska are too cold. Most varieties need more winter chill than South Florida gets.

Do not plant blackberries in Hawaii, where introduced blackberry has become a serious weed of forests and pastures. In the Pacific Northwest, Himalayan blackberry (Rubus armeniacus) is a noxious weed spread by birds, so grow named, well behaved cultivars and remove wild seedlings.

Choosing a variety

Blackberries are erect, semi trailing or trailing, thorny or thornless, and either floricane fruiting (fruit on second year canes) or primocane fruiting (also fruit on the tips of first year canes in late summer and fall).

How to plant

1. Plant dormant, bare root or potted plants from certified nurseries in late winter or early spring, several weeks before the last frost.
2. Dig a hole wide enough to spread the roots evenly. Set bare root plants about 2 inches (5 cm) below the crown, where the stem meets the roots.
3. Firm the soil, water well, and wait until growth starts before fertilizing.
4. Space erect and semi trailing types 3 to 4 feet (1 to 1.2 m) apart and trailing types 6 to 8 feet (2 to 2.5 m) apart.
5. Put up a trellis with two wires, at about 3 and 5 feet (90 and 150 cm) above the ground.

Watering and feeding

Blackberries need about 1 inch (25 mm) of water a week through the growing season, and NC State suggests about 2 gallons (7.5 liters) per plant a day while the fruit is developing. Mulch with pine straw, wood chips or seed free straw to save water and keep down weeds.

Feed with a complete fertilizer once growth starts in spring and again after harvest, well before fall, following the label rate. In established plantings, the spring feed goes on in early spring, before flowering.

Pruning and care through the year

• As new canes grow in spring, spread them in a fan along the wires. On erect types, cut off the tips once canes reach the top wire to make them branch.
• Trailing types are not tipped. Let them reach the top wire and weave them back and forth between the wires.
• Right after harvest, cut all the canes that fruited down to the ground and remove them; they will not fruit again.
• In winter, shorten the side branches of erect types to 12 to 16 inches (30 to 40 cm) and thin to four to eight canes per square yard.
• For primocane types, either prune as above for two crops, or mow all canes to the ground each winter for a single late summer to fall crop.

Harvesting

Berries are at their sweetest when they turn a dull black. Shiny black berries are less sweet but keep longer in the fridge. Pick every few days; the harvest lasts three weeks or more depending on variety. Expect a small crop the year after planting and a full one the year after that.

Harvest runs from about May in Florida and the Gulf South to July and August in the North and the Pacific Northwest. Refrigerate berries straight away and use them within a few days, or freeze them on trays.