when and how far to prune knock-outs

10 years ago

I am new owner to a home with about 8 knock-out rose bushes. They were unpruned last spring-summer and ended up huge...at least 4-5x4 feet. This past late fall I pruned them to about 2 feet tall which is what they are now.

1) Should I prune them shorter?
2) When should I do it? I am in NE Ohio. A friend told me I should not prune them now (headed to 50 degrees today) because it'll encourage growth which will be killed when it freezes hard again, which it certainly will.

Thanks for your advice,
Bonnie

Comments (6)

boncrow66
10 years ago
I have to tell you that my name is Bonnie Jean too! I don't see many people with the name Bonnie much less the same middle name. I live in Texas and I have several knockouts and I have found it really doesn't matter how far you cut them back they always do well. I usually prune mine in February but we have a milder winter here in SE Tx. I camehome one day and my hubbie had pruned my knock outs so short I felt sure they wouldn't survive but they did and looked great when they grew. Knockouts are very hardy so I think you will be safe in anything you do to them. I would think if you pruned them in November that that should be good for this spring. But who knows, live and learn. Good luck!

Bonnie
Bonnie
Original Author
10 years ago
Wow, I have never met another Bonnie Jean!

I have heard the same thing about cutting them back hard, that it doesn't bother them.

Still left with the question of when.

Thanks for your input.
nicholas_delo 7a
10 years ago
In NJ I prune mine when the forsythia starts blooming (I think a lot of others do the same as this is a good indication spring has officially begun).

Other than that, you can just wait until you no longer have to fear frost or ice damage, so more or less when the temps at night reliably stay above freezing.
diane_nj 6b/7a
10 years ago
I think down to 2' is enough. Once last frost date has past, you'll want to check to see if what is left is still green to the tips. Of not, you can prune off that bit, or just leave it. Knock Out will send out new growth to cover.

Like nicholas.delo, I prune in late winter/early spring, meaning late March/early April, when the forsythia blooms. I don't prune in the fall.

This post was edited by diane_nj on Mon, Mar 17, 14 at 9:42
jim1961 / Central Pennsylvania / Zone 6
10 years ago
I usually prune late March early April here...
This year is much colder than usual so who knows?
When the forsythia bloom in your area would be a good time to prune.
Bonnie
Original Author
10 years ago
Thanks everyone. I'll watch out for the forsythia, but will keep the overall weather in mind. I'll look out for when when it's starting to send new growth out. My crocus is starting to bloom and for sure there is plenty of winter left.