Days to germination: Must overwinter
Days to harvest: Second season after planting
Light requirements: Full sun or some shade
Water requirements: Water during dry spells
Soil: Well-drained, but will tolerate most soils
Though wild blackberries can be found in fairly cool areas of the world, cultivated varieties usually thrive best up to around zone 4 or 5. They may look a lot like raspberries, but blackberries are definitely a different plant.
People tend to think of blackberries as a wild, thorny and untameable fruit. But with a little effort and pruning, you can keep your blackberry plants firmly under control.
Blackberries are sweet enough to be eaten fresh, and they cook up great for sauces, pies or other dessert recipes. They are high in vitamins A and C, as well as other antioxidants.
Starting from Seed
Blackberries are usually started from cuttings or seedlings, rather than from seed. If you do choose to start your plants by seed, you should plant late in the fall because the seeds need the chilling period of winter before they will sprout. Since they need to be outside for the winter, you should plant your seeds out where you want your blackberry patch to be rather than start seeds for transplanting.
For purchased seedlings or blackberry cuttings, you should plan on getting them planted early in the spring once the ground has thawed enough to dig. Space your plants about 3 to 4 feet apart, and give them some extra space to spread out in front and back. Blackberry vines can grow 7 to 10 feet long, if you let them. The vines are going to be thorny, so don’t plant your blackberries along a walkway.
Dig a hole deep enough to accommodate the roots, and add some compost while you’re at it. Don’t choose a low-lying place for your berry plants. They need very well-drained soil and will suffer if their roots are kept water-logged..
Some varieties will vine more than others. Ones that vine will almost certainly need support but more erect ones may not. If you intend to use a trellis for your plants, you should have it in place right when you first plant the seedlings.
Vining blackberry types include Black Satin, Marion and Chester. There are a few thornless types as well. The erect types are more disease and frost resistant, and include types like Cheyenne and Shawnee.
Blackberries will produce fruit on 2-year old branches or canes. Once a branch has produced berries, it won’t produce anymore. So to keep your blackberry bushes productive, you should prune out the canes after they’ve been harvested.
Other than that, you may want to just prune out any extra new canes to keep your bushes a reasonable size. If you allow all the new growth to develop, you will quickly have an enormous hedge of blackberries to deal with.
There are a few new varieties that produce a small harvest on first year canes, and so there may be a point in the future where you can get “everbearing” blackberries just like you can with raspberries. They’re not commercially available just yet.
During the first year, keep your plants watered when the weather is dry but don’t overdo it. They don’t like soggy roots. After the plants are established, you shouldn’t need to water them at all unless there is a really prolonged dry spell. Blackberries are a very low-maintenance plant. Each spring you can give your bushes a feeding with complete fertilizer mix, or an addition of some compost to their soil.
For growing in a container, you should stick to the erect varieties as they are a bit easier to control in a limited space. Even so, you may want some additional support.
Keep the branches pruned, and limit the number of canes you allow to develop each season. One plant per pot, as long as the pot is at least 16 to 20 inches across.
Pests and Diseases
Keeping your ripening berries away from the birds will probably be your biggest challenge with blackberries. A fine net or mesh cover is a good idea if the birds are taking too many berries.
Other than birds, blackberries are a very hardy plant for the garden and will most likely not succumb to any difficulties though there are a few threats to watch for.
Botrytis rot is a fungus that will attack both the leaves and fruit of your blackberry bushes. Black spots can start to show up on the leaves and infected fruit can get gray and visibly moldy. You can help prevent this and other mildews by improving the air flow through the bush. Prune out some of the central canes for better ventilation. Once discovered, you can treat with fungicide.
Blackberry rust is appropriately named, and looks like reddish-brown patches on the leaves. It’s a fungus, and can be treated like any other fungus. Trim off the infected leaves. And like with botrytis, remove a few extra canes to help ventilate your plant more. Rust likes humid conditions.
Harvest and Storage
Depending on the age of your seedlings, you may have fruit the first year. More likely, your first berries will be in the second season. After that, they will continue to produce fruit for up to 20 years. Unless you are growing a thornless blackberry, you should wear gloves when berry picking.
Though it depends on your specific variety, you will have a fruiting season in late summer or early fall.
When you pick blackberries, the small core will come away from the stem and is part of the edible fruit. Don’t judge the ripeness by how easily it comes off the core, because it won’t happen. If you are used to picking raspberries, this may seem odd at first.
Wait until the bright red color has completely given way to the deep purple they are named for. Taste a few berries, and you can quickly tell if they are ready to pick.
Keep your berries in the fridge for up to 5 days. If you want to keep them longer, you can freeze them fresh or after they’ve been cooked.