Put together Blackberry Bushes For Winter: Overwinter Blackberries

You may have seen unkempt blackberry bushes before, perhaps even on your property, sporting crazy growth and canes all over the place. This member of the bramble family can be tall and unruly and sometimes very thorny, making it unpleasant to deal with. However, proper care, including winter preparation, makes blackberries a joy to grow and eat!

Healthy blackberry bushes can survive 15-40 years, giving you decades of tasty berries. Whether you planted them yourself or acquired some messy ones, let’s talk through eight easy steps to take to prepare your bushes for winter.

Step 1: Remove Fallen Fruit

Clean up fruit trees and bushes after fruiting to prevent pests and diseases.

This goes for all fruit trees and bushes. To prepare your blackberries for winter, clean up once all fruiting has ceased. Rake up or compost debris from fallen, rotten, diseased, or damaged fruit. Fallen fruit attracts critters and pests like yellowjackets and mice, which no gardener wants hanging around. If there is enough fallen fruit, swarms of stinging insects will move in and stick around, causing major issues

Diseases and pest eggs can hide in fruit, leaves, and old canes that aren’t cleaned up. Don’t ignore this step to decrease the risk of disease and control pests next year. 

Step 2: Soil Test and Fertilize

A person wearing black and blue gardening gloves, firmly grasping a trowel, ready to begin some outdoor work in the garden. The diligent gardener carefully excavates the soil around a vibrant currant bush, ensuring the plant's roots are undisturbed.Fertilize blackberries strategically for healthy growth.

Blackberries can be fertilized all at once in the winter when you do your annual pruning. Otherwise, it can be spread out incrementally, leaving the last feed for the fall during your clean-up. If you go this route, you’ll do one in the spring when your bushes wake up, two throughout the growing season, and the last in early or late fall. This last feed will help grow healthy primocanes for next year. 

The pH should be 5.5 to 6.5 for blackberries. Add lime to increase the pH or soil sulfur to lower it if needed. The pH was likely adjusted upon planting, but it should at least be monitored annually for peak performance. The Phosphorus (P) and Potassium (K) levels are equally important as they support root development and fruit production and can even increase stress tolerance. More is not better here, so only apply exactly what is needed. 

Soil testing each year will help guide your amendment plan and ensure your blackberry plot has ample nutrients. You can do it at home with a kit or through an extension office or university for more advanced results and specified recommendations. 

Best Fertilizers for Blackberry Bushes

In the foreground, a pair of gloved hands gently cradle potassium nitrogen fertilizers. The hands' textured gloves provide a stark contrast to the dark, rich soil beneath, highlighting the anticipation of growth.
Fertilize blackberry plants with nitrogen annually by using urea or ammonium sulfate.

Again, use your soil test results as a guide, or speak with your local extension office for help. Oklahoma State University Extension also created the Small Fruit Fertilization and Maintenance Schedule for small fruit growers, which might be useful when researching amounts and types of fertilizers. 

Step 3: Control Those Weeds

A close-up captures a hand firmly gripping a bunch of weeds. The hand exerts gentle pressure as it plucks these intrusive plants from the ground, demonstrating care and precision in gardening.
Manage weeds for healthy blackberry bushes through mulching and using landscape fabric.

Blackberry bushes are shallow-rooted, and any weeds will be big-time competitors. Weeding as part of your winter preparation routine is essential, especially if your bushes are new and just getting established. Creating mulched paths and adding compost along your plants after cultivating should help keep the weed pressure down. 

Use landscape fabric, compostable mulch, or a silage tarp to manage weeds throughout the season. 

Step 4: Don’t Forget to Water! 

An industrious gardener, standing beside a flourishing blackberry bush in a sun-kissed garden, carefully waters the verdant plant with a red hose. The gentle, rhythmic flow of water cascades from the red hose, nurturing the bush's vibrant green foliage.
Properly water fruit plants weekly throughout the growing season until winter.

Like most other fruits, watering one to two inches per week throughout the season and up to four inches while fruiting is very important to healthy, full, and juicy fruits. However, once fruiting stops, you must not forget to continue caring for your plants. They should be watered until the ground freezes so they go into winter hydrated and happy. 

Remember, if the ground is frozen, the water is too, so it’s inaccessible to your plants. Hydrate them before this occurs. 

Step 5: Protect from Snow and Ice

A gardener in a cozy blue winter jacket, wearing cream, yellow and green gardening gloves, carefully tends to a blackberry bush. The gardener wraps the bush in a snug-fitting white cover, shielding it from frost and maintaining a safe haven for future growth.
Use windbreaks or covers to protect blackberries from cold temperatures.

Hopefully, you’ve selected a variety of blackberries suitable for your growing zone. The variety will determine how to winterize your bushes because some do just fine in low temperatures without much protection or special treatment, while others need lots of TLC to survive the cold. 

Some methods to try:

  • Plant a windbreak if you live in a particularly windy region.
  • A windbreak fence made of sturdy, high-density polyethylene can be installed along your blackberry patch. This should help block wind and divert some blown-in heavy snow.
  • Covering with a burlap sack is a commonly used practice among blackberry growers. You could also use a simple cotton bedsheet and secure it over your bush. Of course, this would only be realistic if you have just a few plants. Remove the cover in the spring.

Best Varieties for Cold Climates 

A close-up of a bunch of blackberries on a branch; some ripe, glistening deep black, others unripe, displaying a hue of red. The leaves serve as a textured backdrop to the varying shades of the berries.
‘Illini Hardy,’ one of the best blackberry varieties, yields fruit from May to June.

‘Illini Hardy’ is an extremely sturdy self-supported bush that fruits from May to June and is hardy down to zone 4. 

‘Chester’ is a thornless variety with large yet mild, late-season fruits. This variety performs well in zones 5-8.

‘Ebony King’ is mostly thornless, can produce large, super tart berries, and survives in zones 2-3. They’re late bloomers, meaning no delicate blooms are at risk of damage during spring frosts. This berry flavor lends itself perfectly to baking. 

‘Apache’ is said to survive in zone 5 without winter protection. It’s thornless and very high-yielding. 

Step 6: Mulch

A close-up of a man's hands wearing gardening gloves as he delicately holds a mound of fresh tree mulch, showcasing his gardening expertise. The earth beneath his gloves is blanketed with a lush, brown carpet of mulch.
Choose cold-hardy cultivars and mulch heavily for winter to protect blackberry bushes in cold climates.

Tender blackberry bushes are fairly hardy and can tolerate temperatures from 0-10°; for most, that’s just fine. However, if you live in an area with harsh winters and temperatures below 0°, selecting a cold-hardy cultivar is advised. That said, mulching is the next most important thing you can do for your berry bushes to prepare them for winter. 

Blackberries prefer well-draining soil that’s at least 3% organic matter, so during your fall clean-up, add good quality, aged compost to the base of your plants. This will help retain moisture, improve the soil structure, protect the crown, suppress springtime weeds, keep it slightly warmer, and may even deter bugs. Remember, when you feed the soil, it feeds your crops. 

Other mulch options that work well on blackberries:

  • Woodchips
  • Grass clippings
  • Cover crop debris from grains such as wheat and rye
  • Pine straw

Step 7: Prune

A person's hand grips a pair of red pruning shears. The sharp blades of the shears are positioned delicately at the tip of a blackberry cane, ready to trim it.
Pruning blackberries at the right time for specific purposes enhances fruit quality and yield.

Pruning blackberries depends on the type you’re growing. Some should be pruned in the summer, while others need to be pruned while dormant. Pruning will increase yields and quality of fruit and make harvesting easier in the future.

We prune to remove damaged, weak, and older canes and to open up the bush canopy to let more light in. Both will lead to increased production and larger berries. 

Supplies needed to prune: 

  • Sturdy, thick gloves
  • Loppers
  • Sharp, clean pruners
  • Twine for tying up

Erect Blackberries 

A person with a gentle gesture offers a slender blue rope to intertwine within the sprawling, intricate network of the blackberry branches. The rope creates a secure and supportive tether for the fruit-bearing bushes in the garden.
Prune erect blackberries for cold hardiness and uniform growth by reducing main and side canes.

Erect blackberries include the most cold-hardy cultivars and can be grown successfully in most regions. These should be dormant-pruned, reducing the bush to three main floricanes (second-year canes) spaced 10 inches apart. Lateral (side) canes should be trimmed to 12-18 inches long. Remove any lateral canes that are below your lowest trellis wire.

Once pruning has been completed, tie up your bushes to be evenly supported on all sides. Ultimately, each bush should be in a slightly “V” formation. Next year, new primocanes will grow upwards, filling in any gaps. 

Summer tipping, although typically performed to have stronger canes that support heavier fruit the following year, can also be done to have a stronger bush going into winter. Your bush may hold up to heavy rain, snow, and wind.

When primocanes emerge throughout the growing season, try soft-tipping. This is when you nip off about two inches of the tender growing tip once the cane has reached three feet in height. Hard-tipping involves pruning off a thicker part of the stem with shears, which is only recommended in floricane varieties with experienced growers in warmer regions. 

Hard-tipping wounds increase the likelihood of disease that could kill the bush altogether. In primocane varieties, this would result in no fruit. After soft or hard-tipping, apply a preventative fungicide to decrease the risk of cane blight. 

Semi-erect Blackberries

Within a sunlit garden, a hand delicately grips red pruning shears, poised near a blackberry cane, ready for a precise cut. The metal trellis stands as a sturdy support for the flourishing plant in the garden's embrace.
Pruning semi-erect blackberry bushes benefits from summer tipping and winter pruning for optimal growth.

Pruning may come a little later in the year for this type of bush as they are a later summer fruiting type that may still be fruiting into fall. Like erect varieties, these benefit from summer tipping and winter pruning, as listed above. 

Trailing Blackberries 

A blackberry branch elegantly trained on a horizontal wire trellis. The serrated leaves are a vibrant green, contrasting beautifully with the red and deep purple-black blackberries that hang in clusters.
This variety requires support in warm regions due to their growing habit.

Trailing blackberry varieties do not produce stiff canes like the other types and cannot support themselves. Without trellising to help them grow vertically, they trail along the ground, hence their name. Trailing blackberries are grown in warmer regions as they are early fruiting and the least cold hardy of any varieties. 

This type of berry bush should not be tipped and must be managed throughout the growing season to ensure proper airflow, healthy fruit production, and light penetration. Growers in warm growing zones may leave the canes on the ground while others tie them up so they’re safely off the ground. Cover them with mulch or row cover if left on the ground. 

Pro tip: No matter what type of blackberries you have, inspect your bushes for pest and disease damage and remove canes as needed while you prune. Treat as necessary. 

Step 8: Protect from Critters

Against the backdrop of a weathered garden shed, a young groundhog pup, with soft brown fur and curious eyes, stands on its hind legs. The groundhog reaches towards the lush, green leaves of a blackberry bush for a munch.
Protect blackberry bushes from wildlife with deterrents like Mylar tape and pinwheels.

Blackberries aren’t just a tasty treat for humans. Birds, mice, voles, and deer may show interest in your bushes. Deer may eat the foliage right down to a nub

Here are some ideas to keep various critters away from your bushes:

  • Deter birds by using Mylar tape or scare tape. Pinwheels are an inexpensive and effective deterrent.
  • Keep mice and voles away by keeping grass and meadows cut low, installing tree guards, and, if those fail, setting traps. Voles love to burrow under landscape fabric and can hide in mulch, so don’t put anything too close to the canes.
  • Deer don’t like to hang out where humans and other animals do. Spray coyote urine around your plot to keep them away. You can also send your dog out there to guard the area. After a few nights of loud barking and a potential chase, they may just not stop the next time they’re passing by.
  • Rabbits have been known to gnaw on berry bush canes over the winter, and who can blame them? Keep them away by using tree wrap, sprinkling pepper flakes, blood meal, or garlic spray, or with low-strung chicken wire.

Key Takeaways

A sunlit blackberry tree stands tall at a picturesque local organic farm. The tree boasts a vibrant contrast of ripe and unripe blackberries, with some glistening in deep, dark purple hues while others remain a bright, tangy red.
Blackberry pruning, trellising, and mulching are essential for successful blackberry cultivation.

  • Proper blackberry bush pruning is vital to their success. Primocanes are new growth and may not produce fruit in the first year. Floricanes are second-year canes that produce fruit and then die back. 
  • Trellising helps hold fruit load and doubles as protection against harsh winter weather.
  • Mulching helps your soil health and retains moisture and warmth going into winter. 

Final Thoughts 

Blackberry bushes get a bad rap, but they are a great addition to any garden when well cared for. Prepare them for winter by pruning, staking, mulching, and deterring pests. Decreased risk of disease and pests will lead to healthy, fruiting bushes. Do it right, and get ready to have an abundance of blackberry jam next season.

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