Blackberry plants are a familiar sight on roadsides and waste ground where they can form impenetrable mounds and barriers of arching thorny stems. In a good year, they can produce huge crops of delicious fruits that look like a large black raspberry and make them popular with us as well as birds and rodents. These wild plants are unruly and thuggish but their best attributes have been bred into a range of garden-worthy varieties that have no thorns but still produce fairly delicious fruit. In our gardens we generally restrain them by training them against a wall or fence or growing them into a tree or over a shed like a climbing rose. The berries are delicious raw or made into jam, high in antioxidants they are a ‘must’ if you have room for a plant or two.
Companions Marigolds to draw predatory insects like ladybugs and hoverflies
Quantity 1 plant per household – more if you have room.
Black Satin thornless variety with large sweet fruit produced between February and March. Grows to about head height. Good for warm areas.
Navaho thornless variety with medium-sized sweet fruits produced from March to April. Good for all parts of the country.
The best time to plant blackberries is from autumn into winter when plants are dormant.
Plant blackberries in a sunny spot but with some shade from afternoon sun. Protect from strong winds. Good for growing countrywide, they can handle winter frosts down to -6 degrees centigrade. They are often trained against trellis or fences.
Blackberries like a rich, free draining soil with lots of organic material in it. Soil should be slightly acidic – so look for lots of organic material as an indicator. If your soil is sandy or slightly sticky then you’ll need to add peat and well-rotted compost at the time of planting and continue to mulch with rich compost as your plants get established. You can always grow a blackberry plant in a raised bed or a container filled with peat and well-rotted organic compost if you have a sticky clay soil.
Plants should be spaced two full strides apart. Soak plants in water before planting them.
Prepare the planting area. Soil should be weed-free and well dug through to at least a full spade’s depth. Add well-rotted compost and peat if necessary and mix with surrounding garden soil. Carefully remove blackberry plant from container by turning it upside down and holding the plant across the base of its stem with a spread hand. Tap the bottom of the container until the plant and its root ball come loose. If it is in a plastic plant bag simply slit it down the side whilst the plant is standing in the planting hole, you can then slip the plastic bag from underneath. Handle plants by the root ball to prevent damage to stems and shallow roots. Place blackberry plant in a hole that is just larger than the container it came in. Back fill around root ball making sure there are no air pockets. Water well and mulch with a finger-thick layer of peat, pine needles, shredded bark or untreated sawdust.
If planting in a container ensure it is large enough. Half barrels look good with blackberries and they are the right size too. Use a rich compost with peat in it and plenty of organic material. Add slow release granules or sheep pellets before planting. When blackberries are grown in containers they should be constantly monitored to ensure soil is moist – particularly in dry weather. Plants are often placed against a wall with trellis on it to which they can be attached or with a metal training pyramid or cylinder standing above the pot.
Keep plants weed free and maintain constant moisture levels – this is especially important during spring and summer when plants are growing and crucial once plants have formed fruit. Always water at the base of plants – avoid splashing foliage as this can spread fungal disease.
Feed: Depending on how well you have composted the ground you might want to give your developing plants an extra boost with some liquid seaweed or worm juice every 6 weeks. If you maintain a nutrient rich layer of mulch around their base this should give them all they need in the first few years as they become established.
Flowering: Blackberries flower in spring, they are self-pollinated but bees can help to improve pollination and increase yields.
Care: Tie stems to training wires or trellis as they grow. Keep plants open and ensure good airflow – especially in warmer areas where humidity can result in fungal diseases like mildew.
Fruit are formed in mid to late summer when they start to ripen. Harvest does not last that long - normally between 4 and 6 weeks. Regular picking keeps fruit ripening. Fruits are ready when they turn from red to a deep, shiny black. They are best left for a few days after they have changed colour before picking. Fruit should come away from the stems easily when they are fully ripe. Taste is, of course, the ultimate test of readiness – blackberries should be sweet. Try to pick on a dry day and don’t wash fruit as this causes them to deteriorate quickly.
Storage: Blackberries keep in the fridge for up to a week as long as they are not piled high in a bowl. To freeze, pop freshly-picked, unwashed berries onto a plate or tray in the freezer. When they are frozen add them to a bag. Repeat this process over a period of time until you have frozen and stored all you want. When they are defrosted they will collapse due to excess moisture and are best used in puddings and jams where they are cooked.
In winter cut back all the canes that have produced fruit to ground level and remove any others that are damaged or spindly and weak. Fresh young canes left on the plant will grow to produce the next season’s crop, pinching out their tips encourages growth of fruit bearing side shoots. Keep plants to about half a dozen stems to prevent overcrowded stems and small fruit.
Blackberries can suffer from a range of pests and disease - some of which are easier to deal with than others. Green vegetable bugs, caterpillars and passion vine hoppers can be tricky customers to regulate in larger plants. Aphids, thrips and scale insects can be treated with Neem oil spray. If grown in the right soil and the right location and kept weed-free plants should be less susceptible to diseases such as mildew. Birds are an issue as soon as fruit start to ripen so protect your plants with mesh.