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Blackberry canes produce an edible berry and will spread to become a bountiful berry patch. If left on its own, a blackberry patch can quickly become an impenetrable bramble. Pruning your blackberries will not only help keep the prodigious growth in check, but pruning will improve the yield and contribute to the overall plant health by controlling diseases and pests.
The most important type of pruning you can do for your blackberries is to remove old canes that have already borne fruit. Shorter varieties will benefit from tipping, while long trailing blackberries can require some pruning to control the lengthy canes. It is also important to remove diseased canes and any unwanted suckers from your berry patch.
How Blackberries Grow
Once planted, a blackberry will quickly spread underground by rhizomes that produce new plants. Also, any long canes that droop and touch the ground can take root and create a daughter plant.
Blackberries are a perennial, meaning that the roots will stay alive and come back year after year. In most cases, however, the plant operates as a biennial and only bears fruit on canes that are two years old. New canes that grow each year are called primocanes and can be identified by their fresh, new green growth. The following year, these canes are referred to as floricanes which will bear fruit and then die. Floricanes generally have woodier stalks with dark, mature-looking leaves.
While there are dozens of different varieties, there are three general types of blackberries: trailing, erect, and semi-erect.
Trailing blackberries produce long, sprawling canes that can reach over 5 meters (about 18 feet) in length. They are generally supported by trellises to keep the canes off the ground and under control, though in the wild these long canes can be seen growing over the ground and blanketing other plants.
Erect blackberries form short, sturdy canes that can support themselves. Many varieties found in nurseries are erect as they are generally easier to grow if you are just getting started, and they can be more reasonably grown in smaller areas.
Semi-erect blackberries, as the name implies, are the middle ground between the other two types. Semi-erect form longer canes than erect blackberries, but might still require some light trellising to support them.
Of course, you do not have to prune your blackberries and your brambles will often grow just fine on their own. However, whether you grow trailing, erect, or semi-erect, your berry patch will often do better with some form of pruning. Let’s look at the 7 ways to prune your blackberries.
- Remove Floricanes
- Tipping Erect Blackberries
- Controlling Trailing Blackberries
- Pruning Semi-erect Varieties
- Pruning “Everbearing” Blackberries
- Removing Diseases Canes
- Eliminating Unwanted Suckers
1. Remove Floricanes
No matter which variety of blackberries you grow, the most important pruning you can do for them is remove spent floricanes. The canes will die once they have finished bearing fruit, and the dying canes will return their nutrients to the root system. After the canes have died back in the late fall, cut them off close to the ground. Be careful not to cut into the crown as this can damage the buds of next year’s primocanes.
Some growers advocate for pruning out the floricanes immediately after harvest as the canes are softer to cut, and it is easier to know which canes need removal. This is a perfectly fine practice and will not hurt your blackberries in any way.
Removing floricanes after fruiting has several advantages for your plants. It opens up space for new growth to flourish and won’t sap energy and nutrients from the roots. Pruning floricanes allows light to penetrate the center of the plant and improves air circulation which will keep your blackberries healthy and reduce the chances of diseases and pest infestations. If you leave floricanes year after year, your blackberries will become a thick, prickly mass that will be difficult (and oftentimes painful) to harvest.
2. Tipping Erect Blackberries
Tipping erect blackberries is the practice of removing the tip, or terminal bud, from new canes as needed throughout the growing season. Even though the plant is erect, it can still send out canes that are 2 meters (6.5 feet) long which can quickly become scraggly and out of control. Pruning the tip of the primocane helps the canes produce strong, sturdy stalks and will yield an abundant harvest the following year.
The growing tip of the cane contains a hormone called auxin which causes the cane to grow vertically and inhibits side branches from growing. Tipping removes the hormone and promotes the production of laterals, which results in more flowers and fruits in the second year.
How long to make your canes after tipping depends on how much space you have, and what size you want your plants to be. 120cm (4 feet) is a good length for erect blackberry canes, but you can tip them back to 60cm (2 feet) long and still produce a good harvest. It is also a good idea to trim any laterals back to about 45cm (18 inches) so they stay maintained and sturdy.
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3. Controlling Trailing Blackberries
Apart from removing spent floricanes, trailing blackberries generally require very little pruning. Unless you need to trim an out-of-control cane, it is not necessary to tip trailing blackberries, and tipping can be disadvantageous to your plants. You want to encourage long, healthy growth that will bear a plentiful harvest. Trailing blackberries perform best when they are controlled by a sturdy trellis and your time will be well spend training the canes early in the year.
As you train your trailing blackberries to their trellis, you might come across a particularly unruly cane. In this case, it is advantageous to prune back the cane so it fits better with the rest of your berry patch.
4. Pruning Semi-erect Varieties
Semi-erect varieties of blackberries have characteristics of both erect and trailing varieties and do well with both trellising and tipping. Training your semi-erect blackberries to a short trellis will keep them off the ground, and tipping them will encourage lateral growth and more fruits next year. Throughout the growing season, prune the primocanes back to about 1.5 meters (5 feet) long, and remember to remove all floricanes after they have finished bearing.
5. Pruning “Everbearing” Blackberries
Everbearing blackberries unfortunately do not flower and bear fruit all year long. Instead, everbearing varieties are sometimes called “primocane-fruiting” and will bear fruit on the canes in the fall of the first year and then again the following year. Everbearing varieties are erect blackberries, and the primocanes should be tipped.
Everbearing blackberries are generally not a great variety to grow if you live in a cold, northern climate with a short growing season. I live in Zone 2b, and our first frost date is usually around the middle of September. Since everbearing primocanes generally produce fruit around September we would get a very small crop if we got one at all.
Like all blackberries, everbearing prosper with the removal of the dead floricanes. However, another more drastic way to prune your everbearing blackberries is to cut all your canes back to the crown at the end of each year. Some producers like this as it gives one large harvest in the fall. The downsides of this method are that it doesn’t utilize the biennial nature of the blackberry, and it is definitely a risky venture if your growing season is fairly short.
6. Removing Diseased Canes
Pruning out diseased canes is an important part of maintaining healthy blackberries. Even with careful pruning, blackberries quickly become a dense patch that can harbour and spread diseases very quickly. Regularly check your plants and remove any canes that show signs of disease or pest infestations. Do not compost these canes, but burn or properly dispose of them.
7. Eliminating Unwanted Suckers
Eliminating any unwanted suckers is again something that all blackberries benefit from. As we have already seen, blackberries spread far and wide underground by rhizomes. A rhizome is a plant stem that runs underground from the main plant. Roots form from nodes on the rhizome and a new plant is born. Some blackberries have been known to send up suckers from rhizomes 3 meters (10 feet) from the parent plant.
Thankfully, most suckers don’t spread this far, but it is important to keep the suckers under control unless you want your whole garden to become a blackberry patch. It is a good idea to mark where you want your blackberries to stay, and cut out any suckers that develop outside this area. These suckers can then be transplanted back in with the rest of your blackberries, or you can sell them or give them to friends and family.
Tips to Prune Blackberries Successfully
Choosing the Right Pruner
It is important to have the right tool for the job and bypass pruners are the best choice for pruning your blackberries. Bypass pruners have a sharp blade that slides past a curved base, similar to a heavy pair of scissors. Bypass pruners will make a clean cut that causes minimal damage to the plant and heals quickly.
When using bypass pruners, make sure the blades are nice and sharp. A sharp blade will make a clean cut that will heal faster and won’t set the plant back as much. When cutting, position the pruner so that the base is on the side of the cane that you want to keep. The base side will cause less damage to the cane while the blade side of the pruner tends to crush and damage the stem. Rest the cane against the curve, and squeeze firmly to make a good cut.
If you trim out a sick or diseased cane, make sure to clean the pruners before using them on another plant to avoid spreading the disease. Cleaning the pruners in a 10% bleach solution or any natural disinfectant works well.
You can also pinch off any young growth with your fingers. For any older growth, however, it is much better to use a pruner as breaking the plant can significantly retard recovery.
Another article you might want to purchase to work with your blackberries is a good pair of gloves. Blackberry thorns are notoriously sharp and you don’t want to prune them with your bare hands. Alternatively, you can plant thornless blackberries and help save on band-aids.
Prune Just Above the Nodes
Whenever you prune your blackberries, you want to cut just above a node on the stem. A node is the slightly swollen, “knobbly” part of the plant stem. All leaves, offshoots, and branches grow out of these nodes. The smooth part of the stem between the nodes is simply called the internode.
Place a cut at a slight angle a few millimeters above the node. Leaving too much of the internode can introduce rot and disease to your cane.
Propagate Blackberry Cuttings
But what should you do with all the scraps that you pruned off the canes? Even though removing parts of the canes will produce healthier plants, it sometimes feels like a shame to throw the cuttings into the compost bin.
Our tip is: simply grow more blackberries! Blackberries can easily be propagated by placing these cuttings in water or planting them back into the soil. Roots will sprout from the cuttings and you will have a whole new blackberry to plant in your berry patch.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.