Prune your thornless blackberries twice every year. In late fall, remove second-year canes that have produced fruit in the previous harvest season. Blackberry canes die after their second year and should be removed. Do not remove any first-year canes since they will still produce fruit. Once the spent canes are removed, wait until early spring for the next pruning steps.
In spring, cut the remaining standing canes to a height of 3.5–4 feet (105–120 cm). Then, cut any lateral branches coming off these canes to a length of 12–16 inches (30–40 cm). If you are growing primocane-fruiting blackberries, the canes will produce fruit in their first and second year. When pruning primocane fruiting blackberries, prune first-year canes to 12 inches (30 cm) in height to remove the section that has already produced fruit and died.
Do Thornless Blackberries Need Pruning?
Like all blackberries, thornless blackberries require twice-yearly pruning. This is due to the fact that most blackberry canes die shortly after they produce fruit. This means that the canes that have provided berries will die and not produce fruit again, so they should be cut off. New canes that have sprouted should be left so that they can produce fruit in the future. This process is slightly different depending on whether your thornless blackberries are floricane or primocane type. We will cover the specific pruning tips for each of these types below.
- All thornless blackberries need pruning each year.
- After their second year of growth, blackberry canes die and should be removed.
- Pruning your blackberries gets rid of dead canes, increases fruit yield, and makes harvest easier.
Unpruned blackberries will produce less fruit, be harder to harvest, and contribute to a messy garden. The canes that have already produced fruit will die. If they are not removed, these dead canes make a messy bramble patch, even without thorns. Unpruned blackberry canes will grow long, trail along the ground, or invade other parts of your garden. So, in addition to removing dead canes, trimming new canes is essential.
When Do You Prune Thornless Blackberries?
Prune your thornless blackberry plants between the end of the harvest season and the beginning of spring growth. This means late fall through early spring are the best times to prune blackberries. Depending on temperatures in your region, plan to prune between November and March. Once your blackberries have gone dormant and the leaves have turned brown, you can safely begin pruning.
- Prune blackberries when they are dormant—between late fall and early spring.
- Once your blackberries have dropped their leaves in fall, you can begin pruning.
- Some pruning steps are best performed in late spring, so split blackberry pruning into two stages.
Blackberries respond best when they are pruned twice annually. In late fall, remove dead second-year canes by cutting them off at ground level. Then, wait until early spring to trim the remaining canes. This process makes it easy to spot buds and make the correct cuts on the canes you wish to keep. Don’t worry, we’ll cover all the specifics below.
4 Steps for Pruning Thornless Blackberry Bushes
Pruning thornless blackberries is simpler than pruning other varieties for one simple reason: no pesky thorns. A pair of gardening gloves is still advised even though you don’t have thorns to worry about. Other than gloves, all you need is a pair of pruning shears to get started. Here’s all you need to know:
Remove Dead Canes
After their second year of growth, blackberry canes die. These dead canes should be removed so that new canes can thrive. However, your plant will have a mixture of first-year and second-year canes. During pruning, you should not remove any first-year canes that will produce fruit the following summer. To remove only the dead second-year canes, find the canes that are brown in color and cut them off at the base of the plant. Do not remove any green or reddish-brown canes—these are first-year canes.
- Blackberry canes die after their second year and should be removed.
- Prune off dead canes at ground level.
- Dead canes are dark brown in color.
- New canes are green or red-brown.
- Do not remove new canes during pruning.
Pruning second-year canes applies to both floricane and primocane blackberry varieties. All blackberry canes die after their second year. This step is best done in the fall, just after harvest ends. This makes it easy to identify the second-year canes.
Trim Upright Canes
Once you have removed all the second-year canes on your thornless blackberry plant, wait until late winter or early spring to trim the first-year canes. To do so, trim each remaining cane to 42–48 inches (105–120 cm) tall. Pick a point right above a bud or “node” and trim the cane at this point.
- Trim first-year canes to a height of 42–48 inches (105–120 cm).
- Trim the canes just above a bud, to promote lateral growth and increased berry production.
- To make spotting buds easier, you can wait until early spring for this pruning step.
- This step applies to floricane-fruiting blackberries, we’ll cover primocane-fruiting blackberry pruning specifics below.
“Tipping” blackberry canes in this fashion encourages lateral growth. Since lateral branches produce the most berries, this pruning step ensures you’ll get a good harvest in the upcoming season. It also keeps your thornless blackberries from getting too tall. Extremely tall canes trail on the ground or grow out of reach. Either way, it makes harvest difficult and means you’ll lose delicious berries.
Shorten Lateral Branches
After you’ve trimmed the upright stem of your remaining first-year canes, move on to trimming the lateral branches. These are the branches that grow outward from the main stem of the cane. Each branch should be pruned to 12–16 inches (30–40 cm) in length. This will keep the lateral branches to a manageable length throughout the growing season.
- Trim lateral branches growing from upright canes to 12–16 inches long (30–40 cm).
- Cut the canes just above a bud.
- This step—like the previous one—is best done in early spring.
- Like the previous step, this one applies to floricane-fruiting blackberries. The next step contains specifics about primocane-fruiting blackberries.
As with trimming upright canes, trim lateral branches just above a bud. This is easiest to do in early spring, since the buds will be present and visible. Trimming these lateral shoots further increases blackberry yield.
Pruning Primocane Varieties: Special Steps
Some thornless blackberries are primocane fruiting varieties. This means the canes will produce fruit in the first year and second year before dying. Most blackberry varieties (called floricane varieties) do not produce any fruit on first-year canes. Only second-year canes produce fruit before dying. Because primocane fruiting varieties of thornless blackberries are unique, they require some special pruning care. Follow these tips:
- In the fall, remove all second-year canes that have died.
- Inspect your one-year-old canes.
- Primocane-fruiting thornless blackberries only produce berries on the top half of the cane in their first year.
- Remove the dead tops of one-year-old canes by trimming 2 buds below the dead section.
- Canes are typically trimmed to 12 inches (30 cm) tall in this process.
So, the only true pruning difference between floricane and primocane blackberries is the height at which first-year canes are pruned. If you are growing a primocane blackberry, you can safely cut all the canes back to 1 foot (30 cm) tall in early spring. These first-year canes will still produce fruit, so you’ll get two years of harvest out of a single cane.
How Do You Know if Your Blackberries are Floricane or Primocane?
If you’re not sure whether your blackberries are a primocane or floricane variety, trim them according to the guidelines for floricane varieties. Then, keep an eye on your plant. If the new canes that sprout from the ground in spring do not produce fruit, you are growing floricane berries. This means the canes only produce fruit in their second year of growth. After harvest, these canes die and should be removed.
- Floricane blackberry canes only produce canes in their second year, then die.
- If new blackberry canes produce no fruit during their first year, you have floricane blackberries.
- Primocane blackberry canes produce fruit in their first and second year, then the canes die after their second year.
- If first-year canes produce berries near the tips of their canes, you have primocane thornless blackberries.
If the new canes that sprout from the ground in spring DO produce berries, then you are growing primocane-fruiting thornless blackberries. These first-year canes will mostly produce berries at the tips of the canes, not near the base. In order to keep track of new canes, you can tie a loose piece of colored string around new canes. Then, pay close attention and see if they bear fruit.
Pruning Thornless Blackberry Bushes Tips
In order to prune your thornless blackberries, follow these tips:
- In late fall, remove all second-year canes by cutting them off at ground level.
- Wait until early spring to perform follow-up pruning steps.
- In spring, trim first-year canes to 3.5–4 feet tall (105–120 cm).
- After trimming upright canes, trim lateral branches on these canes to 12–16 inches (30–40 cm).
- When growing primocane-fruiting blackberries, cut canes back to 12 inches (30 cm) tall after their first year of growth.
These simple tips for pruning blackberries will allow you to get the most berries from each plant. It helps to know what variety of blackberry you’re growing, but with a little practice and some time in the garden, you’ll soon know exactly what type of blackberry you have.