University of Illinois Extension
Pruning Blackberries for Productivity
 

[February 11, 2019]   As a child, my grandparents would send me to the unmanaged portions of their property to pick blackberries with my sisters. Most of the time we brought enough back for grandma to make a pie, and probably just as much sun sweetened fruits in our bellies.

For backyard garden blackberries, active management of these brambles will boast more produce. Suggested blackberry cultivars for central Illinois 'Chester' (thornless), and 'Illini Hardy' (thorny), a very cold hardy cultivar, which produces great tasting fruit but has millions of thorns. "Everthornless" is a thornless variety developed at University of Illinois, but is actually suited for the Pacific North West's mild winters.

Blackberries are perennial crops but the shoots, or canes, that grow are individually biennial. That means that each individual cane will only live for two years.

In early spring, plant new plants 4 to 6 feet apart in a hedgerow when the soil is not wet. Plant hedgerows 10 to 12 feet apart for Illinois semi-erect varieties. Avoid planting in soil that recently had nightshades such as tomatoes, potatoes or eggplant.

Most plants purchased online will come bare root, and should be soaked in water at least 30 minutes before planting. Plants bought from nurseries or greenhouses may come potted up and will not require soaking if properly cared for prior to planting. To plant, dig a hole one and a half times larger than root system and fan the roots out. Water immediately and at least every two to three weeks after planting. Remove the tips of laterals, and snip the main stem back to 4 inches from the ground to force new growth.

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The first year of growth, the canes are called "primocanes" and do not produce flowers or fruit. In the second year of growth, the canes are called "floricanes" and they produce flowers and fruits, and can be preoductive for up to 20 years. If you let blackberries and raspberries grow without pruning or cutting back, there would be a mixture of primocanes and floricanes present at any given time, which can lessen productivity and harbor disease and pests.

In early March, remove any broken, dead or diseased canes first. Canes should be cut as close to the ground as possible. Prune to only four to five large floricanes canes spaced to about four inches apart. The remaining canes should be cut back to four to five feet tall and lateral branches should be cut back to a foot. Thornless blackberries need to have all laterals removed within 24 inches of soil.

Spring- Mulch shredded bark up to three inches thick prevent weeds and conserve moisture. Apply fertilizer a month after planting.

Fall- Mulch with shredded leaves or straw up to three inches thick to protect roots and prevent heaving. Keep mulch away from roots.

[News Source: Kelly Allsup, Extension Educator, Horticulture
Terri Miller
University of Illinois
County Extension Unit #16 Director]