How Do You Prune Thornless Blackberry Bushes

You prune thornless blackberry bushes by cutting back the canes that produced fruit last season and thinning out the new ones for next year.
 
It sounds technical, but it’s actually pretty simple once you know what you’re looking at.
 
Unlike their thorny cousins, thornless blackberry bushes won’t fight you back while you work, which makes the whole job a lot more enjoyable.
 
If you’ve been wondering how do you prune thornless blackberry bushes without accidentally ruining next year’s harvest, you’re in the right place.
 
In this post, we’ll walk through exactly how to prune thornless blackberry bushes, when to do it, and the mistakes to avoid so your plants keep pumping out berries season after season.
 
Let’s dig in.
 

How Do You Prune Thornless Blackberry Bushes?

You prune thornless blackberry bushes by removing the old canes after they finish fruiting and cutting back the new canes to keep them manageable.
 
Thornless blackberries, like the popular ‘Triple Crown’ or ‘Navaho’ varieties, grow on canes that live for two years.
 
The first year, a cane grows vegetatively and produces no fruit.
 
The second year, that same cane flowers, fruits, and then dies.
 
That two-year cycle is the whole secret behind pruning thornless blackberry bushes correctly.
 
Once you understand it, the job becomes obvious.
 

1. Remove the Floricanes After Harvest

The canes that just gave you berries this summer are called floricanes.
 
They’ll never fruit again, so there’s no reason to keep them around.
 
Cut those spent floricanes down to the ground as soon as harvesting wraps up.
 
This cleans up your thornless blackberry bushes and frees space for the new canes to grow.
 

2. Thin the Primocanes

The new green canes growing this year are primocanes, and they’re next season’s berry-makers.
 
Don’t just let them run wild, though.
 
Thin your thornless blackberry bushes down to about 5 or 6 strong, healthy primocanes per plant.
 
Snip the weaker, spindly ones at ground level so the plant puts its energy into the best canes.
 

3. Trim the Canes to a Manageable Height

Once your primocanes reach about 4 to 5 feet tall, tip them by cutting off the top few inches.
 
This encourages side branching, which means more fruit next year.
 
For trailing varieties of thornless blackberries, you can also cut the long canes back to around 5 feet and tie them to a trellis.
 

When Should You Prune Thornless Blackberry Bushes?

Timing matters just as much as technique when you prune thornless blackberry bushes.
 
Get it wrong and you could cut off the canes that were about to fruit.
 
Here’s a simple breakdown of the best times to prune.
 

1. Late Winter for Dormant Pruning

Late winter, while your thornless blackberry bushes are still dormant, is prime time for structural pruning.
 
This is when you remove dead, damaged, or crossing canes.
 
The plant isn’t actively growing yet, so it handles the cuts well and bounces back quickly in spring.
 

2. Summer Right After Fruiting

The other key window is right after harvest, usually mid to late summer.
 
This is when you cut out the floricanes that just finished producing.
 
Doing it immediately helps prevent disease and keeps your thornless blackberry bushes from wasting energy on canes that are done for good.
 

3. Tip Primocanes in Early Summer

If you want bushier plants, tip your primocanes in early summer when they hit your desired height.
 
Just don’t go overboard.
 
A light trim is all your thornless blackberry bushes need to push out those fruitful side shoots.
 

Tips and Mistakes When You Prune Thornless Blackberry Bushes

Pruning thornless blackberry bushes isn’t complicated, but a few small slip-ups can cost you a season of berries.
 
Keep these pointers in mind.
 

1. Never Cut Everything to the Ground

Some folks get overzealous and mow their thornless blackberry bushes down completely.
 
That kills next year’s harvest because you’ve removed all the primocanes.
 
Always leave a handful of healthy new canes standing.
 

2. Sterilize Your Pruners

Clean your shears with rubbing alcohol before you prune thornless blackberry bushes.
 
This simple step stops the spread of diseases like cane blight between plants.
 

3. Don’t Prune Too Late in the Season

Cutting your thornless blackberry bushes in late fall or early winter can leave fresh wounds exposed to cold damage.
 
Stick to late winter or right after harvest instead.
 

4. Keep Things Tidy After You Prune

Rake up and toss any diseased or pest-ridden cuttings when you prune thornless blackberry bushes.
 
Leaving debris around the base invites problems back in.
 

So, How Do You Prune Thornless Blackberry Bushes?

You prune thornless blackberry bushes by cutting out the old floricanes after harvest and thinning the new primocanes to about 5 or 6 per plant.
 
It’s a simple two-year cycle, and once you get the hang of it, the job takes just a few minutes each season.
 
Prune at the right time, keep your tools clean, and don’t hack everything to the ground.
 
Do that, and your thornless blackberry bushes will reward you with buckets of sweet berries year after year.