When and How to Winterize Blackberries

If you’re growing blackberries, you’ll likely need to do some winter preparations.

In mild climates, there’s not much to do at all. But in cooler regions, it’s smart to prepare your plants for the arrival of old man winter.

How much work you need to do depends on what type of blackberry you’re growing and where you live.

In this guide, we’ll talk about the specifics of how to winterize your plants so they come back vibrant and productive in spring.

Here’s what I’ll cover:

What Types of Blackberries Need Winterizing?

Most blackberries (Rubus fruticosus agg.) are hardy to USDA Growing Zone 5b, but gardeners in 4b and 5a can still grow these brambles with a little bit extra of winter care.

Of course, different species and cultivars have different needs, but those listed as “hardy” generally do well down to -10°F, and “tender” types to 10°F.

Plants in areas that experience frequent heavy snow and melt can benefit from some winterizing.

That’s because most blackberries produce the best fruit on canes that grew in the previous year, known as floricanes. So it’s a good idea to protect those year-old canes from the ravages of winter.

Freezing and thawing, heavy snow, wind, and sunscald can all damage blackberry plants. Providing a little winter protection can help mitigate the damage these conditions cause.

In regions with warmer winters, think Zones 7 and up, you don’t really need to do any winterizing, but feel free to do some preparations if you want to be extra sure you’re keeping your plants safe.

Potted blackberries should always be winterized to some degree.

The technique you use will depend on the type of plant you’re growing.

Climbing Types

Climbing types like the Pacific blackberry (R. urisnus) or the blackberry and marionberry hybrid ‘Columbia Star’ can be damaged by freezing temperatures and heavy snow.

To protect the long, climbing canes, you will need to move them off their supports and lay them on the ground.

To do this, before the first freeze sets in, lay some straw down on the ground adjacent to your plant. Two or three inches should do.

Then, gently remove the canes from their supports and move them onto the straw. You don’t need to cover the canes, but you might want to pin them down if they appear reluctant to stay in place.

You can use a piece of wire pushed into the ground, but avoid using rocks or bricks since they block the light and trap moisture.

In cold climates, it can help to bury the canes by placing a thick layer of straw on top.

In the spring after the last frost and when the canes are no longer frozen, gently lift them back up and affix them to the trellis or whatever support you’re using.

Some of the canes might have rooted into the ground, via layering. If that happens, you can either clip away the roots and lift the canes, or snip the cane off on both sides of the root and let a new plant grow where the stem has rooted.

Remove all of the straw and put it in your compost pile.

Upright Plants

For upright plants, you don’t need to do much beyond pruning.

However, if you expect a period of strong winds, especially if the canes are frozen, you might want to wrap them in frost cloth or stake some kind of wind break around the plants.

If you live in an area with regular visits from deer or rabbits in the winter, some protection from these herbivores is in order.

Even if they don’t bother with your blackberries during the summer, they may be hungry enough to go browsing during the winter.

A small fence or netting is usually enough to do the trick.

Container Plants

Container plants are more susceptible to the damage caused by winter conditions than those growing in the ground.

It can help to think of potted plants as though they are growing in one Zone colder than your region.

So if you live in Zone 6, pretend that your berries are growing in Zone 5 and protect them accordingly.

Pots are also more prone to freezing and thawing than in-ground soil, which can cause root damage, soil heave, and cracking of the containers.

If you live in Zone 5, it’s probably best to take your pots into an unheated garage or basement during the coldest months. You’re aiming to keep the plants in temperatures above freezing but below 45°F or so.

Before first frost, prune the plants back leaving about five canes that are a foot or two long in place. Then move the pots to your chosen location.

Don’t water the plants at all unless the soil has been completely dry for several weeks. Then, you can add a little water.

In the spring, after the last predicted frost date, bring the container back into the great outdoors. Do this gradually over the course of a week so you don’t risk sunburning or shocking the plant.

This process is similar to hardening off that we do with seedlings, and involves bringing the plant out for one hour and setting it in or near the area where it will ultimately grow.

After an hour, bring it back in. The next day, add an hour before you bring it back in. Keep adding an hour each day until you have exposed it for a full seven hours. Now you can put it in its permanent spot and care for it as usual.

If you’re in Zones 6 and up, after pruning, wrap the container in burlap or some other protective material and add a layer of leaf or straw mulch to the top of the potting medium to help protect the roots.

When spring arrives, remove the burlap and what remains of the mulch.

Pruning

When the brambles are dormant, this is the time to prune them to encourage new branching and healthy growth.

Blackberries should be pruned in late winter or early spring at the latest. The exception is fall-bearing types. These should be pruned in the fall.

It’s especially important to prune erect types like ‘Navaho’ and semi-erect types like ‘Chester’ and ‘Triple Crown.’

Our guide to pruning blackberries will help make the process crystal clear, but I’ll do a quick rundown here.

Blackberries are made up of primocanes, which are the first-year shoots, and floricanes, which are second-year or older shoots.

You want a nice mixture of both to encourage healthy growth and fruiting. We have a guide to the difference between primocanes and floricanes if you’re interested in learning more.

During the winter, you’ll remove all but four to six of the first-year canes. Remove any damaged or diseased canes. Cut the tips of the remaining canes to encourage side branching.

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