Blackberry, a fruit-bearing plant similar to raspberries, is popular for the dark, juicy berry it produces throughout the summer months. While the root system of a healthy blackberry plant can live and produce for up to 20 years, the canes of the blackberry plant are biennial. They grow the first year (primocanes) and produce fruit the second year (floricanes) before dying. The roots of your blackberry plant will send up new shoots every growing season. When you plant your blackberries, make sure you get healthy plants from reputable growers to avoid planting diseased plants. Likewise, grow your blackberries in the conditions they prefer.
Grow blackberries in well-drained, fertile, sandy loam soil with full sun exposure. Blackberries prefer warmer climates, but because of late flowering, are not usually damaged by frost.
Grow blackberries in rows running from north to south. This will help with fruit production and will limit sun scald. Space erect tame blackberry plants 2 to 4 feet apart. Trailing blackberry plants should be spaced 4 to 8 feet apart within a row. Rows should be 8 to 10 feet apart. Keep rows between 12 and 18 inches wide, removing any canes which shoot outside of the row.
Train your blackberries to a trellis. Even erect varieties which do not require a trellis will be easier to manage if trained to one. For trailing varieties a trellis is necessary to keep fruit from touching the ground and being damaged. Train your blackberries in their second growing season by tying new shoots loosely to a trellis as soon as they reach 4 to 6 feet.
Pinch off the top inch or two of new canes of erect blackberries as they reach 3 feet to encourage lateral branches to grow. Thin and train the primocanes of erect blackberries in late winter and prune branches back to about 12 inches. Remove floricanes (of erect and trailing blackberries) directly after the harvest.
Do not pinch off the tops or prune the lateral branches of trailing blackberries. Additionally, if you live in a colder climate, leave the primocanes on the ground for the winter, covering them with straw after the first hard frost.
Ensure your blackberries receive at least an inch of water every week during the growing season. Dry spells can seriously limit the size of your berries, however, blackberries will not tolerate having soggy roots for more than a day or two. Apply a mulch to help maintain the moisture in the soil.