Growing blackberries

For decades, blackberries or brambles were nearly forgotten in Finland. However, the introduction of the early, hardy native to Finland variety ’Sonja’ in the passing millennium revived interest in this prized delicacy.

In an ideal summer, ’Sonja’ begins producing ripe berries in Finland as early as the start of August. Early ripening is a major advantage, since berries that mature under sunny summer skies gain the most sweetness. Autumn rain can leave the berries watery and tasteless. If ripening starts too late, much of the crop may remain unready.

A warm growing spot is crucial for blackberries. Especially in northern regions and with varieties that need a long growing season, it’s best to use every method possible to speed up ripening.

An unheated seasonal greenhouse can help guarantee a harvest, especially for varieties that require a long growing season. Warmth and humidity encourage blackberries to grow even faster, leaving other plants behind. The ’Thornless Evergreen’ variety grows canes that can reach several meters in length, so it’s recommended to lower them in winter and protect them.

Successful overwintering leads to abundant blooming that also pleases pollinators, which busily buzz around the bright white blooms.

Blackberries—successful growing with these tips

Soil

Rich and moisture-retaining.

Growing site

A sunny, wind-sheltered location is ideal. Especially sensitive and late-ripening varieties do best in a warm spot, for example against a wall or in a seasonal greenhouse with a peak of about three meters. Plant blackberries where there is plenty of space for them and their companion plants to thrive.

Support

This is essential. Attach the canes to a trellis or wires. You can also train the plant like clematis by encircling it with reinforcing mesh. Tie the fruiting canes to the support.

Pollination

Blackberries are self-pollinating but benefit from insect pollination. Make sure pollinators can access the blooms.

Propagation

Can be done from root suckers. Collect the shoots in spring before they start growing. Only propagate healthy, productive plants.

Pruning

Blackberry canes are biennial. Remove fruiting canes in autumn and thin out the new ones in spring. If the variety is upright-growing, leave canes spaced about 25 centimeters apart. For a vining variety, you can keep around a dozen fruiting canes.

Protection

Delicate varieties benefit from protection, especially during cold, snowless winters. Spring sun and wind can also dry out the canes. In a warm spot, canes may begin growing in early spring. Cover any plants that have started budding with frost cloth or several layers of row cover if there’s a threat of frost.

Plant diseases and pests

Viral diseases can hamper blackberry growth and lower yields. Voles and rabbits may nibble on the canes, and field voles can do severe damage under winter covers.

Harvest

Pick the berries as they ripen. The darker the berry, the sweeter the taste. Unlike regular raspberries, the receptacle stays inside the berry. Blackberries also freeze well.