Do i need to prune or cut back knock-out roses?

tlbean2004

6 years ago

I planted a 1.5 gallon knock out back in the spring of 2015.

It is doing good and bloomed great last year and is about 4 ft tall now. Is it necessary to prune them or can i just let it grow and do its own thing?

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Patty W. zone 5a Illinois

6 years ago

Since you are in zone 7 maybe this pruning advice from Paul Zimmerman would be helpful. He has made many videos for all types of roses. There are many reasons for pruning various roses. This one seems to apply to a Knockout. Pruning Roses That Grow From The Base - YouTube

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Comments (7)

jim1961 Zone 6a Central Pa.
6 years ago
last modified: 6 years ago
I've watched two regular Knockouts beside each other downtown for about 4 years now. They have been untouched those 4 years by there owner. They still seem to bloom and bloom each year. They are about 5-6ft high and 4+ feet wide...

I prune our Double Knockouts back alittle bit each Spring...But I did let them go untouched for about 2-3 years after I planted them to let them form there natural shape...

I always take out any dead or unproductive canes...

And I deadhead...
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You probably didn't kill them, but you didn't do them any favors,either. Somehow, some folks in Tennessee have decided that roses are the same plants as other shrubs. This leads to some who severe prune as early as late September and again in November. This sort of thing takes strength away from the plants. Roses don't want to go dormant here. If you cut them in fall, they'll put out new growth in two to four weeks, even though it's not yet winter. That growth will probably be killed in late December, and that earlier cutting will have taken away the stored 'strength' that would go to regrow the plant in spring. I've watched some Knockout that have been pruned three times this fall. I don't know what the heck the grounds crew thinks they are doing, much less why. What you should have done (in my opinion) was go through and snip off broken canes. Then in late December go in and prune back for height, depending on how high you want them to be next year. The winter killed new growth that you are going to get, you'll see it contorted and blackened, you can snip it off in winter as well.
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seil zone 6b MI
6 years ago
The only thing you should do is take out dead would. After that it's up to you. Prune for whatever shape and size you prefer. Keeping them dead headed will encourage then to bloom more and faster.
nippstress - zone 5 Nebraska
6 years ago
The advice you read in rose books to prune back roses to encourage growth is more relevant for hybrid teas to encourage show-type blooms and not at all necessary even for them. You can prune any rose to try to encourage it to grow into a pleasing symmetrical shape once it gets big enough, and certainly deadheading (cutting or pinching off dead blooms behind the flowers) or a periodic haircut of the outermost couple of inches of branches (if you're lazy like me) can jumpstart a rose into increasing or continuing the blooms, but it's totally not necessary.

In our cold zones, some people don't realize that Knockouts can lose branches to winterkill as much as any other rose, so you have to prune out the dead wood or they look unsightly pretty quickly. I spring prune all 75 Knockouts at my church every year now after they posted a pitiful note a few years ago that their "no care" roses looked awful. All they needed was the dead wood taken out, but that is all they need yearly and they bloom more or less all season, though you can see the dead blooms after a while and they slow down as they have more dead than live blooms. I'm just not willing to commit to deadheading or edge trimming all season for that many roses not in my own yard, and they do fine.

Bottom line is I'd let them grow and do their own thing, particularly in zone 7, unless you enjoy the puttering about with roses.

Cynthia
Lindsay K
6 years ago
Most of my knockouts have not needed a lot of shaping or pruning, other than dead-heading and cutting out dead limbs. I have a few on the hottest side of my house that never grew into a pretty shape though. I have been pruning them and trying to fix them for the last couple of years...instead of looking nice and full like all of my others they tend tend to get leggy. If you don't have that problem, I would just let them do their thing!
modestgoddess z6 OH
6 years ago
I'm in zone 7 Maryland. The pink double knockouts planted in front of a local hospital get trimmed down to 2 feet every year and grow back to four feet. These are planted next to a driveway so they probably want to keep them 4x3 feet.
Logan L Johnson
6 years ago
Honestly, with Knock Out ('Radrazz') I just whack mine back when they overgrow, usually during the winter-early summer is a good time to prune (November-June).