covering knockout rose bushes

kss1956October 6, 2011

We may get our first frost tonight-not a hard frost. Should I cover these bushes? If so, what should I use-it is prickly so I am not sure how good sheets would work?



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jim1961 Zone 6a Central Pa.

A light frost will not hurt your roses. Here I do not worry about frosts this late in the year, I just let mother nature do her thing...

    Bookmark   October 6, 2011 at 9:47PM
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michaelg(7a NC Mts)

Temperatures around 27 degrees will kill soft rose tissues, but the hardened canes of Knock Out are OK to well below zero. Visible frost has nothing to do with it.

Covering with sheets can break soft rose stems and, of course, ruin the sheets. As Jim said, best to let nature take its course. You'll probably get some more flowers this month. Roses won't need any attention from you until April.

    Bookmark   October 7, 2011 at 8:58AM
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seil zone 6b MI

A light frost will probably damage any blooms you have right now but otherwise will not hurt the rose. If you want to save the blooms cover them with row cloth, if you have it, or a sheet. Newspaper works too but its almost impossible to keep on. Do not use plastic.

    Bookmark   October 7, 2011 at 10:56AM
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michaelg(7a NC Mts)

seil, whether a light frost damages the blooms depends on the temperature. Flowers can stand 30 degrees. Again, I've done more damage trying to protect roses than I've prevented, but maybe I'm just clumsy.

    Bookmark   October 7, 2011 at 11:22AM
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Thanks for your replies. I have not heard or "row cloth". One reply stated "no attention until April". I assume that means I do nothing-I have a few "gangly" flowers.

    Bookmark   October 8, 2011 at 7:03AM
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seil zone 6b MI

If you don't have any blooms to worry about than I wouldn't bother to cover them. They'll be just fine. Knock Outs are sturdy and a little frost won't hurt them. Row cloth is a soft, light weight covering designed and sold for just the purpose of covering plants to protect them from frosts. You can usually find it at nurseries and should be in stock at the moment for fall frosts.

I agree, Michael. You can actually do more damage trying to cover them sometimes.

    Bookmark   October 8, 2011 at 9:59AM
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dan_keil_cr Keil(Illinois z5)

I never cover my Knockout for winter. It always comes out of winter fine!

    Bookmark   October 8, 2011 at 10:36AM
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Wow - I had no idea that knockout roses were hardy in zone 5 - just another good trait! I have a garden of old roses, but i did purchase one knockout, and so far it is blooming and growing happily in partial shade with no disease whatsoever. I think they have sometimes been criticized by rose folks who don't like roses that are too easy to grow! Not me!


    Bookmark   October 8, 2011 at 1:49PM
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sammy zone 7 Tulsa

This is really interesting to me. I have about 130-140 rose bushes, including 10 Knock Out roses in a bed. In the spring I trim back most of my roses, but the KNock Outs have to be cut back almost to the ground. I purchased my Knock Outs the first year they were available, but mine in zone 7A do not come through the winter nearly as well as my teas and chinas.

Be very careful trying to build up the mulch around your roses to protect them from the cold. You will create a great new home for baby bunnies, mice, and anything else.


    Bookmark   October 9, 2011 at 7:09AM
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mad_gallica(zone 5 - eastern New York)

IME Knock Outs are *very* susceptible to canker. They did much better after I pointed this out to everybody who would listen, and it was understood that mulch wasn't to spend the winter anywhere near those canes.

BTW, they hit their winter limits somewhere around -15F. So I don't really consider them a zone 5 rose, but more of a real 6a rose. Given the pathetic winter performance of a lot of modern roses, that is actually an accomplishment.

    Bookmark   October 9, 2011 at 9:28AM
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seil zone 6b MI

Good point, Sammy. Never winterize before the ground is completely frozen or you're just inviting critters to move into their winter digs! Both time I mistakenly covered roses too soon I had bunnies nest in the leaves. They had a built in smorgasborg of my roses to munch on tunneling through the leaves all winter! I never protect now until after Thanksgiving or even later if the weather has still been warm.

    Bookmark   October 9, 2011 at 10:07AM
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michaelg(7a NC Mts)

Comparing what Sammy said and what mad_gallica said, Sammy's cane loss may be owing mainly to canker rather than cold. I don't grow Knock Outs, but plants around here that are just left alone seem to come through the winter fine.

A plant of Mutabilis here that was mulched heavily each winter (because local tradition says teas and chinas aren't hardy) regularly got canker on EVERY one-year-old cane until they stopped doing that. It still gets a lot of canker, though.

    Bookmark   October 9, 2011 at 10:24AM
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I feel that people often cover their roses too early, roses need to be exposed to chilling to signal them to go dormant. I have a 2 temperature rule for covering my tender roses here in z4 that has worked well for me.

(1) do not cover your roses until they have been exposed to 28F or colder several times.

(2) when the weather foreast is for 20F or colder I cover my roses (the 20F rule came from a study done at Boerner Bot. Garden in Milwaukee)

Using these temps, I cover my roses anywhere from about Nov. 10th to Nov. 25th---each year is different.

    Bookmark   October 9, 2011 at 11:35AM
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