If you love the taste of blackberries but don't have the space required to grow them in your home landscape, container gardening may be the answer to your problem. Growing blackberries in a pot is simple, and the rich green foliage can make a lovely addition to your container garden. Sun-loving perennials, potted blackberries grow best when positioned in a full-sun location that receives between six and eight hours of sunlight per day.
Select and prepare a large planting container that can comfortably accommodate the roots of your blackberry plant; usually a 24-inch by 18-inch pot will suffice. Look for a pot that has at least four 1/4-inch drainage holes in the bottom; drill additional drainage holes, if necessary. Measure the bottom of your pot with a measuring tape and cut a wire mesh screen to those dimensions. Place the wire mesh screen in the bottom of the pot. Cover the wire mesh screen with a 2-inch layer of landscaping gravel to prevent the growing medium from being washed away with each watering.
Blend together equal parts peat moss, coarse builder's sand and perlite to create a rich, well-draining growing medium for your blackberries. Add enough of the growing medium to the bottom of the pot to allow your blackberries to be planted at the same level they were planted in their nursery container.
Hold your blackberry plant in the centre of your prepared pot. Add enough of the growing medium to the pot to fill it to the desired level. Use your hands to firm down the surface of the soil around your plant.
Water your blackberries after planting to thoroughly moisten the growing medium. Stop watering when water begins to drip from the drainage holes. Continue to water your blackberries several times a week, or as often as necessary to keep the growing medium consistently moist.
Wait to fertilise your potted blackberries until they produce new growth. Use a fertiliser that has been specially formulated for container gardening. Apply the fertiliser according to the package directions for best results.
Prune your potted blackberry plant in the late summer or early fall to promote vigorous growth in the next growing season. Use sharpened and sterilised pruning shears to cut all but the four strongest blackberry canes down to the surface of the growing medium.
Provide berry plants with a trellis or other support to prevent them from sprawling on the ground. Blackberries can grow in clay, metal, plastic or wood planting containers. When choosing a pot for your blackberries, keep in mind that metal and plastic containers tend to conserve moisture better than pots made of clay or wood. Build a grow box, to fit the exact space available, to establish a berry patch -- and produce many more berries.
Even in ideal growing conditions, container-grown blackberry plants may not produce as many blackberries as their garden-grown counterparts.