Blackberry Bush FAQs

What Is Their Growth Habit?

• Blackberry bushes have either trailing or upright growing habits. Erect blackberry bushes send up stiff canes that eventually arch as they grow and that do not require supports. Trailing blackberries send out long canes that crawl on the ground and must be supported to attain an upright position. Upright blackberry bushes are more cold hardy than the trailing varieties, but trailing varieties might survive winter with a heavy layer of mulch.

What Are Blackberry Bush Canes?

• Blackberry bushes, which are sun-loving perennial plants, have two types of canes. First-year canes are called primocanes, and they do not produce berries. Floricanes are in their second year of growth, and they produce berries, then die back, making way for the next primocanes to become floricanes the following year.

Do All Blackberry Bushes Need a Trellis?

• All blackberry bushes should be trellised, advises Oregon State University Cooperative Extension, because this will make caring for the plants and harvesting the berries easier. A homemade trellis of wire stretched between two posts works well if you have many plants, but if you have only a few, each plant can be trained up a stake that has been driven into the ground.

How Should I Prune Blackberries?

• Primocanes on erect blackberries should be thinned during winter so that only three or four strong canes, each with some foot-long lateral branches, remain on each plant, according to Oregon State University Cooperative Extension. In a thick hedgerow of plants, only one strong cane per 5 inches should remain. Erect blackberries also need some summer pruning. You will need to cut 2 inches from their primocanes, once they become 3 feet tall.

  Trailing blackberries should not be pruned at all during the growing season, but after harvest, you must prune off their floricanes, leaving only 6 to 12 of the strongest primocanes for next season. In cold climates, the canes must be left on the ground, rather than trained up a stake or wire, and mulched. Short or broken lateral branches need to be pruned off. The 18 inches nearest the bottom of the cane should also be free of any lateral branches.

Can I Propogate Blackberry Bushes?

• Blackberry bushes can be propagated by four methods: leafy stem cuttings, root cuttings, suckering and tip layering. The University of Florida Extension service recommends putting 4 to 6-inch cuttings in a peat and sand mixture to root and putting 1/2-inch diameter root cuttings directly into the ground. You can do the same with suckers that you have cut from the mother plant, and you can do tip layering by bending a young cane to the ground and covering it with at least 3 inches of soil, where eventually a new plant will sprout.

How Should I Water and Fertilize Them?

• Blackberry bushes benefit from either manure or 10-20-20 fertilizer. Commercial fertilizer is best applied in early spring when new growth is starting. Manure must be applied in late fall or early winter to benefit spring growth. Applying manure too early promotes late growth, which can result in winter damage. Thin canes or light green leaves mean that the plant needs more nitrogen.

  Blackberries also need about 1 inch of water a week from mid-June until harvest is over. If the weather is very hot and windy, like other plants, blackberry bushes dry out quickly and will need extra water.