Add a tang to summer this year with juicy, flavoursome blackberries.
This prickly customer is easy to grow and, once established, will produce fruit by the bucket load for 15-20 years. But ease of growth and abundance are not their only qualities.
Blackberries are packed full of vitamins and antioxidants for good health.
Wild blackberries have all but disappeared from roadsides and open places where, as kids, we eagerly gathered and feasted on the fresh delights. But wild they are.
By summer's end, wild brambles know no boundary.
They spread everywhere, with the help of birds and animals, and have become a real nuisance, hence councils have made an effort to eradicate them. But they are difficult to eradicate once you have them. According to New Zealand Forest Health Research Collaborative, of the brush weeds, blackberry is second in this country only to gorse, in terms of the volume of herbicide sold for its control.
These days you can buy tamer cultivars that are more compact and have been bred without thorns. A couple of good varieties are "Black Satin" and "Navaho". Black Satin has large, luscious berries. The thornless canes are erect and non-suckering, unlike its wild cousin. It's a fast grower, reaching 1.5-1.8 metres high (the wild blackberry grows more than two metres high) relatively quickly.
Navaho also has erect, thornless stems with a bumper crop of large, sweet fruit in summer. You don't need a lot of space to grow it, because the plant grows upwards, with a self-supporting habit. It's the sweetest of the thornless varieties, although the berries of Black Satin, if left on the vine for a week after ripening to their full colour, will develop a juicy sweetness too.
Navaho is grown by Waimea Nurseries (available in garden centres) and one the staff highly recommend to home gardeners.
Blackberry plants are available in shops now for planting. They thrive in a sunny spot with good air circulation. In humid areas they are prone to powdery mildew and good air circulation will help prevent this.
Blackberries grow best in soils that are high in organic matter, so dig in plenty of compost or aged manure before planting. They like an acidic soil, at its optimum a pH of around 6.0-6.5, although they will grow in a pH range of 5.0-7.0. Add some peat or acidic food to the soil if necessary.
Although the soil should be reasonably moist, it must also be free-draining. Grow your blackberries in raised beds if your soil is clayey or prone to flooding.
When you get your plant home from the garden centre, dig a hole big enough to accommodate the entire root ball. If plants are bare-rooted, position the plant in the hole so the crown (where the roots meet the stem) is about 3-5 centimetres below the soil surface. Backfill with soil to the original soil surface and water well. Potted plants should be planted at the same level as they were in the pot.
About a month after planting, feed your blackberry with a balanced fertiliser, then feed again in summer. Apply ample water during summer to keep the berries nice and plump. Mulching is beneficial to keep the soil evenly moist.
The following winter after planting, cut out the weakest shoots, leaving three sturdy ones behind. These will flower in spring and fruit in summer. New shoots will also develop in spring.
After picking your berries, cut back the fruiting stems to ground level. Blackberries fruit only on two-year-old canes. Once the canes have fruited, they won't fruit again.
Tie the new shoots that began forming in spring to a trellis or support. These will fruit the next season.
You can also leave some of the older canes in place and bend them into a fan shape, where they will form more side branches that will fruit the following year.
You can also tip prune the canes in spring, to encourage the canes to branch out and thus produce more fruit.
If you have a friend or neighbour with a blackberry, you may be lucky enough to secure a cutting. Or take a cutting of your own existing plant. You can propagate blackberries by root and stem cuttings. Root cuttings are taken during winter when the plants are dormant.
Take root cuttings 10-15cm long and about the thickness of a pencil.
On each cutting, on the end nearest the crown, make a straight cut. On the end furthest away from the crown, make an angled cut.
Make up a potting mix containing peat and sand, then insert the straight ends of your cuttings into the mix about five centimetres deep. When they have grown decent roots, you can plant them out in the garden or in a large pot.
You can take leafy stem cuttings the same way – except you take them from the stems in spring or autumn.
When harvesting your blackberries, pick when they're fully ripe.
Blackberries do not continue to ripen after harvesting.
- © Fairfax NZ News