Mow Down those Knock Out Roses!

Knock Out Roses planted on a bank

Knock Out Roses planted on a bank

I get a lot of questions about taking care of Knock Out Roses at this time of year with people unsure of what to do with those vigorous Knock Out Roses that they are sure will be engulfing their yards soon! You really need to hack them back to stubs and people are scared to do this. You cannot kill a Knock Out Rose! These shrubs are tough and can take lots of abuse.

The natural inclination of The Knock Out® Family of Roses is to grow to about 3′ wide x 4′ tall, but they are easily maintained at a smaller size through pruning, and that means severe pruning!. They are ideal for growing in mixed borders, in containers or as a hedge. A hedge of Knock Outs is beautiful! Think of using these instead of Forsythia for a colorful hedging plant that will give you months of blooms.

English: Rosa 'Knockout'

English: Rosa ‘Knockout’ (Photo credit: Wikipedia)

Just like other roses, The Knock Out® Family of Roses perform best when planted in full sun. The soil should be well drained and fertile. In partial shade, they will not bloom as profusely and can get leggy looking.

Plant the roses 4 feet apart to allow for room to grow and good air circulation.

To keep the flowers coming, feed your roses with a fertilizer blended especially for roses. This should be done after each bloom cycle. There is no need to remove faded flowers because these roses are self-cleaning – another task you can remove from your to do list!

Knock Outs planted alongside a house

Knock Outs planted alongside a house

Prune in late winter or early spring, while the plant is still dormant. Remove any dead or damaged wood, do a little shaping if necessary, and take out some of the interior stems to improve air circulation. Every 2 or 3 years remove about one-third of the old branches to stimulate new, fresh growth. If you are trying to keep the roses at a certain height, you can cut them back hard with hedge shears. No need to worry about the usual rose pruning rule of cutting back to an outward facing leaf bud – just lop them down to the desired size. I’ve even seen Knock Out® Roses spring back beautifully after being cut down to 6-inches.

Tiger rests in the knock-out roses

Tiger rests in the knock-out roses (Photo credit: Vicki’s Nature)

About thegardendiaries

Claire Jones is a landscape and floral designer and owner of Claire Jones Landscapes, LLC. She designs and helps people to create their own personal outdoor oasis and loves to write about her gardening failures and successes.
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7 Responses to Mow Down those Knock Out Roses!

  1. Good advice!! I pruned all my roses down 2/3rd’s and they are all doing so much better than last year!!


  2. They posses an amazing vigor that is rare in roses. They are real work horses!


  3. I should have pruned mine down but I did prune all dead branches out. They are easy keepers for sure. Thanks for the post.


  4. They do make a nice low hedge.


  5. But what about witches broom? In response to this post ( ), someone told me I was probably transmitting rose rosette disease to my knockout roses when I pruned them. Do you dip your pruner blades in bleach solution between each cut as one person suggested I do? Altho’ I am fond of my roses, I don’t think I am willing to go to all that trouble!


    • The nice thing about Knock Out Roses is that they are immune to all those nasty rose diseases. Are you kidding? I don’t sterilize anything! I just shear them down and it takes 5 minutes per rose, no careful pruning like tea roses. These are tough shrubs.


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