URBANA, Ill. —- As a child, Kelly Allsup’s grandparents would send her sisters and her to the wilds of their property to pick enough blackberries for a pie. Years later, the University of Illinois Extension horticulture educator recalled the blackberry bushes as gangly, thorny and under-yielding. “Although this was a tactic to get us out of the house, if those wild berries had been pruned in late winter we might have brought back enough for 10 pies,” said Allsup, who now makes her living, in part, advising others how to grow berry bushes. 

To achieve maximum yield from a bush, Allsup advises pruning backyard brambles in February or March when plants are still dormant. This forces the plants to branch out, creating more wood upon which berries can flourish. And while everbearing plants need to be trimmed in late winter, erect brambles need pruning in summer, as well. To make pruning less intimidating, the extension educator recommends identifying the cultivar-- or plant variety-- in order to make a plant-specific plan before bringing out the loppers.

“For example, on a semi-erect blackberry ‘Chester Thornless,’ remove floricanes and diseased canes until there are only six to eight of the strongest primocanes left. On these branches, cut back the tip of the stem to 5 feet. The primocanes will have lateral branches that should be pruned to 18 to 24 inches long. If pruning a thorned variety, wear gloves and long sleeves,” Allsup advised. 

Floricanes are older, overwintered canes-- also known as bramble stems-- that produce flowers and fruit and can be productive for up to 20 years, she explained. These dark red stems are covered in a white bloom, which rubs off and is used by the plant as a sunscreen.

“Without pruning or cutting back canes, the bush produces less fruit and can harbor disease and pests,” Allsup noted. “Old fruiting structures on the plant indicate that the cane is a floricane that should be removed.”

In a paper published by the U of I Extension in late January, Winter Pruning Boosts Blackberry and Raspberry Harvests, Allsup offered specific advice for pruning or mowing brambles and canes:

Everbearing and Biennial Canes: Most brambles produce on biennial canes, but some are everbearing, which means they can bear fruit until the fall. If the primocanes that bore fruit in the fall are left to overwinter, they will fruit again, lower on the cane, in late spring and then die. By mowing down all the canes in late winter, there will be a more abundant fall harvest.

Erect and Semi-erect: Erect brambles, common in both raspberries and blackberries, produce stiff, upright canes that need summer and winter pruning. They tend not to need a trellising system. Semi-erect brambles produce thick, arching canes that benefit from winter pruning. If not supported by trellises, these varieties will bend over to trail along the ground and begin to root, limiting fruit production.

Root Suckers and Hills: Root-suckering brambles create a hedgerow and spread by root suckers. They are thinned by cutting canes to the ground, leaving 6 inches between canes and removing any canes outside of the row. Some brambles retain their individual plant form in a “hill.” To prune, remove last year’s floricanes and tip back the primocanes. 

In addition, Allsup advises that new plants should be pruned to the ground when planted in early spring. Roots should be soaked in water for 30 minutes before planting, unless they were purchased potted. Plant new brambles four to 6 feet apart in dry soil, with hedgerows placed 10 to 12 feet apart for Illinois semi-erect varieties, Allsup said. 

Allsup has recently posted a summary of how to grow raspberries and blackberries in Illinois. It can be accessed at: www.extension.illinois.edu/blogs/2021-01-29-growing-strawberries-and-blueberries.

The Illinois Extension also offers cultivar recommendations for Illinois, viewable at www.web.extension.illinois.edu/fruit/. 

There are 199 farms in Illinois that produce blackberries and dewberries, according to the 2017 Census of Agriculture, on just 151 acres. Within the Farm World readership area, Kentucky has the most farms-- 487-- with land in blackberries and dewberries totaling 268 acres. In descending order of producers, Ohio is next with 404 growers on 310 acres. Indiana has 234 producers on 175 acres, while Michigan’s 200 growers produce them on 152 acres of land; Illinois is last in total producers and acreage for blackberries and dewberries.

In “all” varieties of raspberries, Michigan leads the Farm World readership area with 518 producers and 532 acres. Second is Ohio, with 487 farmers producing raspberries on 343 acres. Indiana, with 160 farms and 77 acres, is third, followed by Kentucky (144-40) and Illinois (134-77). 

When considering production of all berries, Michigan is the most prolific state in the region with 1,566 producers on 25,006 acres. In total, there were 33,919 U.S. farms growing berries on 302,199 acres according to the 2017 census.

While raspberries have traditionally been grown in northern regions, blackberries are more suited to warmer climates. During the growing season, raspberries are known to perform best at temperatures between 70-75 F, while blackberries prefer a slightly warmer environment.

Those who wish to interface with thousands of growers of blackberries and raspberries can register for the North American Raspberry and Blackberry Conference, to be held virtually Feb. 22-25. The group also maintains a Facebook community that is open to all. To learn more visit www.raspberryblackberry.com.