How To Prune Blackberries

Learning how to prune blackberries is the single most important skill for growing a productive patch. It might seem intimidating at first, but it’s a simple process that leads to healthier plants and much bigger harvests. This guide will walk you through everything you need to know, from the basic why’s to the specific cuts.

Pruning does three key things. It removes old, diseased canes to improve plant health. It encourages new growth, which is where your fruit will form. And it keeps your patch manageable, preventing it from becoming a painful, thorny jungle. With a good pair of gloves and sharp pruners, you’re ready to start.

Before you make your first cut, you need to identify what type of blackberry you have. The pruning timing and method depends on whether your berries are summer-bearing or primocane-fruiting.

Identifying Your Blackberry Type

Most traditional varieties are summer-bearing (floricane-fruiting). These produce fruit on canes that grew the previous year. You’ll have two types of canes at once: last year’s (which are fruiting) and this year’s new growth (which will fruit next year).

Primocane-fruiting varieties, like some ‘Prime’ series, are different. They can produce fruit on the current season’s new canes in the fall. This gives you more pruning flexibility, as you can cut them all down if you want a single fall crop.

Essential Pruning Tools

You don’t need fancy equipment, but you do need the right tools for the job and for your safety.

Bypass Hand Pruners: For clean cuts on canes up to about 1/2 inch thick.
Loppers: For thicker, older canes. Their long handles give you more leverage.
Sturdy Gloves: Thorn-resistant gloves are a must, even for “thornless” varieties, as the tips can still be prickly.
Long Sleeves and Pants: Protect your skin from scratches.

Always make sure your tools are sharp and clean. A dull blade crushes the cane, inviting disease. Wipe blades with rubbing alcohol between plants to prevent spreading any problems.

When to Prune Blackberries

Timing is crucial. For summer-bearing blackberries, you actually prune twice a year.

Late Winter / Early Spring (Dormant Season): This is your main structural prune. You thin and shape the canes before new growth starts.
Summer (After Harvest): As soon as you’ve picked all the berries from a cane, you remove it at the base. This is called “caning out.” It makes room for the new canes and reduces disease.

For primocane-fruiting types, you can choose. If you want just a fall crop, mow or cut all canes to the ground in late winter. For two crops (a small summer one and a larger fall one), you remove only the top portion of the canes that fruited in the fall after they’re done.

Step-by-Step: Pruning Summer-Bearing Blackberries

Follow these steps during the dormant season (late winter).

Remove Dead and Diseased Canes: First, cut out any canes that are obviously dead, damaged, or show signs of disease. Look for canes that are gray, brittle, or have cracked bark.
Remove Old “Fruited” Canes: If you didn’t do it in summer, cut all the canes that produced fruit last year right down to the soil line. They are usually darker brown and more woody than new canes.
Thin the New Canes: Now look at the remaining new canes (called primocanes). They are usually greener and more flexible. Select the 4 to 6 strongest, healthiest canes per plant or per linear foot of row. Cut the rest out at the base.
Shorten Lateral Branches: On the canes you kept, look for side branches (laterals). Prune these back to about 12 to 18 inches long. This is where the fruit will form, and shortening them encourages larger berries.
Tip the Canes (Optional): Finally, cut the very tip off the main cane if it’s gotten too tall. Aim for a final height of about 4 to 5 feet. This helps the plant put energy into fruit production instead of just growing taller.

Step-by-Step: Pruning Primocane-Bearing Blackberries

For a single, large fall crop, pruning is incredibly easy. In late winter, simply use loppers or a mower to cut all canes down to ground level. New canes will grow in spring and bear fruit that same fall.

For two crops, it’s a bit more involved. In late winter, only remove the top portion of the canes that fruited the previous fall (about the top third). The lower buds on those same canes will then produce a summer crop. After that summer harvest, remove those old canes completely to let the new primocanes grow for the fall harvest.

Training Your Pruned Canes

Pruning goes hand-in-hand with training. Supporting your canes keeps fruit off the ground, improves air circulation, and makes picking easier.

Trellis System: A simple T-trellis or fence is ideal. After pruning, weave or tie your selected canes onto the support wires. Keep them untangled.
Weave Method: On a two-wire trellis, weave canes between the top and bottom wires in a gentle pattern. This helps manage their vigorous growth.
Fan Method: Spread canes out in a fan shape against a flat trellis. This is simple and effective for a few plants.

Common Pruning Mistakes to Avoid

Even experienced gardeners can slip up. Here’s what to watch for.

Pruning at the Wrong Time: Heavy pruning in fall can stimulate new growth that will be killed by winter frost, weakening the plant.
Not Pruning Enough: Being too timid leads to overcrowding. A dense patch gets poor sunlight and air flow, resulting in small fruit and disease.
Making Ragged Cuts: Always use sharp tools. A clean cut heals fast. A crushed, torn cut is an open door for pests and fungus.
Leaving Stubs: When removing a cane, cut it flush to the ground or the main stem. A long stub will die back and can become a point of entry for rot.

Aftercare and Maintenance

Once you’ve finished pruning, a little extra care sets your plants up for success.

Clean Up: Rake up and remove all the pruned cane debris from the area. Don’t compost it if you suspect any disease; throw it away or burn it.
Fertilize: Apply a balanced fertilizer or compost around the base of the plants in early spring as growth begins. This feeds the new canes.
Mulch: Add a 2-3 inch layer of wood chips or straw around the plants. It conserves moisture, suppresses weeds, and keeps the root zone cool.

FAQ: Your Blackberry Pruning Questions Answered

What happens if you don’t prune blackberries?

If left unpruned, blackberry plants become a tangled thicket. The old canes shade out new growth, fruit size diminishes dramatically, and disease risk skyrockets due to poor air circulation. The harvest becomes very difficult to reach.

Can you prune blackberries in the fall?

It’s generally not recommended for summer-bearing types. Light cleanup is okay, but save major pruning for late winter. For primocane types you plan to mow down, fall pruning is fine but late winter is still easier and provides winter protection for the crown.

How do you prune overgrown blackberries?

Reclaiming a neglected patch takes courage. In late winter, put on thick gloves and cut everything down to about 12 inches tall. This resets the plant. It may sacrifice one season’s fruit, but it’s the best way to start over with a healthy, manageable structure.

How short should you cut blackberry canes?

For lateral branches, 12-18 inches is ideal. For main canes, tipping them to 4-5 feet tall is a good rule. When removing old canes completely, cut them as flush to the ground as you possibly can.

Pruning blackberries is an annual ritual that pays off with buckets of sweet, healthy fruit. By understanding your plant type and following these simple steps, you’ll keep your patch productive and under control for years to come. Your plants will thank you with their vigor and abundance.