When To Cut Back Thornless Blackberry Bushes

You should cut back thornless blackberry bushes during two main windows: in late winter while they’re still dormant, and right after they finish fruiting in summer.
 
Getting the timing right matters because thornless blackberry bushes, like most brambles, grow on a two-year cycle and produce fruit on canes that are one year old.
 
If you prune at the wrong moment, you can accidentally remove the very wood that would have given you berries.
 
In this post, we’ll walk through exactly when to cut back thornless blackberry bushes, why each season matters, and how to tell the difference between the canes so you always prune with confidence.
 
Let’s dig in.
 

When to Cut Back Thornless Blackberry Bushes

Knowing when to cut back thornless blackberry bushes comes down to understanding their growth habit.
 
Thornless blackberry bushes send up new canes each spring, and those canes stay vegetative their first year.
 
The following season, those same canes flower, fruit, and then slowly decline.
 
That’s why the best time to cut back thornless blackberry bushes is tied to these two distinct stages.
 

1. Late Winter Pruning While Dormant

The ideal time to cut back thornless blackberry bushes is in late winter, usually February or early March, before new growth breaks dormancy.
 
At this point, the plant is asleep, so pruning won’t shock it, and you can clearly see the structure of every cane.
 
Cut back any canes that fruited last year, since they won’t produce again.
 
Also trim the tips of the newer canes to encourage side branching, which leads to more berries.
 
This dormant window is when you do the bulk of the work on thornless blackberry bushes.
 

2. Summer Pruning Right After Harvest

The second key time to cut back thornless blackberry bushes is immediately after you finish picking berries.
 
Once fruiting wraps up, the canes that produced this year’s crop are spent and will never fruit again.
 
Cut those old canes back to the ground so the plant can redirect energy into the new canes.
 
Removing them also improves airflow, which reduces disease pressure on the thornless blackberry bushes.
 
Just be careful not to confuse the old canes with the fresh green ones that will bear next year.
 

3. A Quick Tip-Trim in Early Summer

There’s also a light trim you can do in early summer on the new canes of thornless blackberry bushes.
 
When a new cane reaches about three to four feet tall, pinch or cut off the top few inches.
 
This forces the cane to branch out, and those branches are where next year’s flowers form.
 
It’s a small cut that pays off big when you’re growing thornless blackberry bushes for maximum yield.
 

Why Timing Matters for Thornless Blackberry Bushes

Timing is everything when you cut back thornless blackberry bushes because the plant fruits only on second-year wood.
 
If you prune too early in spring after growth starts, you risk cutting away developing flower buds.
 
If you wait too long in fall, the plant may not have time to harden off before cold weather hits.
 
That’s why the steady rhythm of dormant pruning plus post-harvest cleanup keeps thornless blackberry bushes productive year after year.
 

1. Avoid Pruning During Active Bloom

Never cut back thornless blackberry bushes while they’re flowering or setting fruit.
 
Any heavy pruning during bloom stresses the plant and can cause you to lose the current season’s harvest.
 
Stick to the late-winter and post-harvest windows instead.
 
 

2. Don’t Prune Too Late in Fall

Fall isn’t a great time to cut back thornless blackberry bushes either.
 
Pruning stimulates new growth, and tender new shoots won’t survive the first hard freeze.
 
Wait until the plant is fully dormant in late winter to make your cuts.
 

How to Tell Which Canes to Cut

Before you cut back thornless blackberry bushes, you need to know which canes are which.
 
Floricanes are the canes that fruited this year, and they look brown, woody, and tired.
 
Primocanes are the fresh green canes that grew this season and will fruit next year.
 
For thornless blackberry bushes, cut the brown floricanes to the ground and leave the green primocanes alone.
 

1. Look at the Color and Bark

Old fruiting canes on thornless blackberry bushes have darker, peeling bark.
 
New canes are smooth and bright green or reddish.
 
Once you spot the difference, pruning becomes second nature.
 

2. Check for Side Branches

Canes that already have flower clusters or leftover fruit spurs are the ones to remove.
 
Fresh canes without any flowers are the keepers on your thornless blackberry bushes.
 

3. Follow the Spacing Rule

After you cut back thornless blackberry bushes, thin the remaining canes so they’re about six to eight inches apart.
 
Good spacing keeps air moving and sunlight reaching every part of the plant.
 

So, When to Cut Back Thornless Blackberry Bushes?

You should cut back thornless blackberry bushes in late winter while they’re dormant and again right after harvest in summer.
 
Late winter is when you remove old canes, tip the new ones, and shape the plant for the coming season.
 
Summer is when you clear out the spent canes that just finished fruiting so the new growth can thrive.
 
Get the timing right and your thornless blackberry bushes will reward you with bigger harvests every single year.