Shrub Roses

(December 2011)

My Knock out roses are in their third year and have never been pruned. When is the best time to do so, and how do I prune them?

Knockout roses are considered shrub roses, so do not require the severe pruning of hybrid tea roses, but they still should be pruned every year in late February. I would imagine yours got a bit gangly going three years without being pruned. Take them back by 1/3 – ½, making selective cuts in the bush—don’t shear them into a ball with a hedge trimmer. You want them looking natural after being cut back. Knockout roses bloom on the new growth, so you want to encourage a full plant, with plenty of growth, so you get more blooms.

(February 2011)

I would like to know when I should cut my knockout roses back. I waited until May last year and I realized I should have cut them sooner.

Knock out roses are considered a shrub rose, so pruning of about 1/3 should be done in late February when we prune hybrid tea roses. With the winter we are having, everything seems to be behind schedule, so if you don't get around to it until mid March you should be fine. Late February is typically chosen because we like to get the pruning done before new growth has really kicked in. Knock outs bloom on the new growth, so late pruning simply delays the first flowers.

(March 2010)

We have one double pink Knock-out rose growing in a container. It grew rather large and is somewhat misshapen, and new leaves are starting to bud. Is it time to trim it? Do standard rose-pruning techniques apply?

Many of the Knock-out Roses grew quite dramatically this past growing season with all the rain. You do want to do some pruning annually on these shrub roses, but not as severely as we do on hybrid teas. Selectively prune back by one third, pruning to buds or small sprouts that are growing in the direction you want the plant to grow. Don’t cut all the branches at the same height, do so with staggered cuts to get a fuller plant and more flowers. Prune annually like with other shrub roses in late February through early March. Most roses are sprouted and growing by now every year when we have mild winter weather—they are actually slower this season due to the colder temperatures.

(March 2010)

I have a question about spots on the stems of knock out roses. Is this a disease? I thought knockouts were supposed to be disease resistant. Do they need to be sprayed like other roses? The plants in question are in our church courtyard and only get drip irrigation.

Knock out roses are very disease resistant and I would not spray them. We did see a few signs of blackspot last season, due to all that rain. That was pretty atypical as far as our growing seasons go, so I am not judging the disease resistance on this past year. Prune your knock outs as you would any shrub rose now, removing up to 1/3 of the old growth. Watch the plants this spring and if you see any problems, let me know. I think the Knock-out series are outstanding shrubs with almost constant bloom from late spring through frost and they are low maintenance to boot!

(Feb. 2010)

We have one double pink Knock-out rose growing in a container. It grew rather large and is somewhat misshapen, and new leaves are starting to bud. Is it time to trim it? Do standard rose-pruning techniques apply?

Many of the Knock-out Roses grew quite dramatically this past growing season with all the rain. You do want to do some pruning annually on these shrub roses, but not as severely as we do on hybrid teas. Selectively prune back by one third, pruning to buds or small sprouts that are growing in the direction you want the plant to grow. Don’t cut all the branches at the same height, do so with staggered cuts to get a fuller plant and more flowers. Prune annually like with other shrub roses in late February through early March. Most roses are sprouted and growing by now every year when we have mild winter weather—they are actually slower this season due to the colder temperatures.

Last week you talked about pruning Knock Out Roses. I don't know what they are. I have two bushes I planted last year. They have come through the winter just fine but are pretty rank....tall & skinny. They are climbers -- one is called Golden Showers and the other is a C.L. Pearly Gates pat # 10,640. I was thinking I needed to prune these. Are they "Knock Out" roses and should I go ahead and prune them.

Knock OutTM Roses are a variety of roses, and considered one of the new "environmentally friendly" roses that are easier to grow, requiring less sunlight, spray programs and fertilization. There are now red, pink and yellow Knock Out™ Roses. They would be labeled as such. They are not given other names. Yours are not Knock OutTM Roses. Climbers should be pruned every year, but not until after the first flush of flowers. Some climbers only bloom once a year, while others bloom all summer. Let them flower, then remove one or two of the older, longer canes. Prune to a new bud within a foot from the ground.

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