Two of the most popular shrubby fruit plants in North America are raspberries and blackberries. Both species are from the Rubus genus. And both are known as bramble fruits, which grow in dense, shrubby masses that can be almost impenetrable once they are fully mature. Despite the fact that it is difficult (and sometimes painful), pruning these plants is essential. Left unpruned, they will grow into massive plants with lower fruit production and higher susceptibility to disease. So if you want to continue to enjoy their delicious fruit and keep them from overtaking your garden, it's necessary to learn the proper ways to prune raspberry and blackberry bushes.
When to Prune Raspberries and Blackberries
Raspberries are generally pruned at two times of the year: in late winter or early spring and during the summer growing season for maintenance.
Blackberries are also pruned at two times of the year: in the early spring when they are "tip-pruned" and in the late summer for a general cleanup.
Equipment / Tools
- Heavy gloves and eye protection
- Stepladder (optional)
- Support fencing or stakes
Pruning Summer-Bearing Raspberries
Summer-bearing (floricane) raspberries will provide one large harvest, usually in late summer or early fall. These raspberries bear fruit on 2-year-old canes, the ones that sprouted the previous season. Summer-bearing raspberries can be further categorized as early season, mid-season, and late-season in terms of when they bear fruit. The harvest period lasts about four to five weeks.
Cut All Canes Near Ground Level
In late winter or early spring, prune all canes (or stems) that bore fruit the previous year. They won't fruit again. These canes will have grayish, peeling bark. Cut them off near ground level using loppers or bypass pruners.
Remove Outside Canes
Cut back the canes that are growing outside of a 12- to 18-inch row footprint of the plant. Raspberries are much easier to tend and harvest if they are kept confined in well-defined rows. Don't worry about pruning too much. Raspberries are very hardy and can bounce back from aggressive pruning.
Remove Unsightly Canes
Remove any spindly or very short canes.
Thin the Rest
Thinning the rest of the canes will allow for about 4 or 5 of the healthiest, tallest, and fattest canes left per foot along the entire length of the row.
Tie the Canes
Tie the canes to fencing or stakes for support
Prune Unwanted Canes
During the summer, prune any dead, broken, or diseased canes that you spot. Also, remove any canes that sprout up outside the designated row area.
Pruning Everbearing Raspberries
Everbearing (primocane) raspberries aren't really everbearing. But they generally have two harvests per season: one in mid- to late summer and one in fall. The fall crop will probably be a bit lighter and is produced on canes that developed during the current season. Many everbearing raspberries bear so late in the fall that they are not practical for gardeners in short-season climates. If you want everbearing raspberries to produce two crops each year, prune them as you would summer-bearing raspberries. But if you want to force a single larger crop in the fall, use the following procedure.
Prune the Whole Bush
Prune back the entire raspberry bush to ground level in early spring.
Thin the Canes
As the canes grow back in the summer, thin them to about 6 inches apart. Keep the sturdiest canes, and remove suckers outside your designated row footprint. This technique will give you a larger fall harvest. Plus, it's helpful if you also have summer-bearing raspberry bushes and you want staggered harvests.
Prune Unwanted Canes
Throughout the summer, prune any dead, broken, or diseased canes, as well as any canes that sprout up outside the row footprint.
Pruning blackberries is quite similar to pruning raspberries. Blackberries don't grow as enthusiastically as raspberries, but they also will yield better with regular pruning. As with raspberries, they're prone to diseases that can spread rapidly if the plants aren't maintained.
Prune Fruit-Bearing Canes
In the fall, prune all canes that bore fruit shortly after harvesting your blackberries. Dispose of the clippings, as dead canes can spread disease.
Thin the Canes
In the early spring, thin the canes to about 5 to 7 per plant.
Prune Side Branches
Also in the spring, prune back side branches on the remaining canes to about a foot long, containing roughly 12 buds. This "tip-pruning" will encourage the plant to branch out, leading to more fruit.
Tie the Pruned Canes
Tie the pruned canes to support fencing or stakes.
Inspect the Plants
In the summer, routinely inspect your plants and remove any dead, diseased, or broken canes.
Raspberry and Blackberry Pruning Tips
Both raspberries and blackberries have serious thorns, so wear thick gloves and long sleeves when pruning. However, there are some modern blackberry varieties that are virtually thornless, making pruning a lot less hazardous.
Also, always use clean, sharp tools. Canes that are crushed rather than cleanly severed can provide an avenue for insects and disease-causing pathogens to enter the plant.
The goal when pruning these fruit bushes is to ensure that light and air can get to the inside parts of the plants. To facilitate pruning, contain the plants in a row. Keep the base of the bushes within a 12- to 18-inch footprint by pruning any suckers that poke up outside that boundary. The tops of the bushes will arch nicely, providing plenty of fruit.
For new raspberry plants, prune back the canes to 4 to 5 feet tall during the first few years of growth. This will ensure that the bush gets plenty of light, which is essential to fruit production. It also makes harvesting easier if you keep the canes at a reasonable height.
With young blackberry plants, prune the tips of all new canes to encourage side shoots. This is where the next season's blackberries will grow.
Growing Raspberries in the Home Garden. University of Minnesota Extension Website