Are Blackberries A Good Choice To Grow In Containers?

Blackberries (Rubus spp.) — dark purple, sweet-tart fruits high in vitamins and disease-fighting compounds – are protected by thorny canes that twist into impenetrable brambles when left unattended. While you may be used to seeing them grow wild, or under cultivation in outsized fields, compact, thornless varieties are a good choice for containers, as long as you choose a suitable cultivar and a large enough pot. Blackberries are perennials with biennial canes, or stems, of two types. Primocanes appear in the first year of the plant's growth, floricanes in the second. This information is useful for gardeners planning to grow blackberries in containers because, among the many varieties of blackberries, primocane-fruiting erect cultivars are the best for container growing. Choosing a thornless variety takes some of the pain out of gardening.  

Blackberry plants are generally hardy in USDA zones 4 to 9. You can check the USDA website to find out what growing zone you're in. Depending on the type, the plant may be trailing, semi-trailing, or erect and are thorny or thornless. Some cultivars produce fruit twice a year. Another factor that may influence your decision is the amount of space the container needs. Blackberries, with some slight variation among cultivars, need large pots to accommodate their deep, extensive root systems. If you have room, trailing blackberries can thrive in containers. However, if space is limited, choose an erect, or compact, variety like 'Baby Cakes' (a thornless plant that bears fruit in the fall) or 'Ouachita' (an erect, high-yield cultivar). 

Choose a spot for your blackberry container that gets six or more hours of full sun each day for ample fruit production. When buying the right planter, search for a container that's large enough and deep enough to accommodate the blackberry's roots and has good drainage. Plants grown in containers as large as 20 to 30 gallons will still need pruning so that they don't get too big. Fill the container with commercial potting mix, not garden soil. It's probably not necessary, but you can mix slow-release fertilizer into the potting mix.

Blackberries can be planted from seed, but it will be two or three years before you have fruit to harvest. Instead, purchase an established bush at your nursery. Dig about a 2-inch deep trench in the potting mix, lay the roots of the blackberry plant in the ditch, and cover them with potting mix. Berries need a lot of water, and container plants usually need more because the soil dries out quickly. Don't let the surface of the soil dry out completely between waterings, and watch for wilting – it's a sign the roots need irrigation. Water until liquid flows out of the drainage holes in the pot. Container blackberries need to be pruned for continued health and to control the size of the plant. In summertime, trim the top few inches off the tops of canes, while dead or diseased canes should be pruned when the plant is dormant.