This is my second year of knock-out rose bushes. Last fall I didn't do anything to them and they did OK. Should they be cut back this fall and to what height? Anything else? Thanks.

Since most Knockouts are grown on their “own roots” you don’t have to worry about mulching them over the winter to protect the graft union--because there isn’t one.

Personally, I don’t do a thing to my Knockouts in the fall or winter, because I like the way they add to the structure and framework of the winter garden. On a pretty day in February, I go out and prune them back to about a big basketball size. At that time I also start fertilizing; the plants should be fertilized after that about once a month or so during the growing season. If you want to cut your Knock Outs back in fall, simply wait until we have a couple of good hard freezes to send them into dormancy, and then prune away. Remove all trimmings of course, just as you would any other perennial pruning project.

Knockouts are disease resistant, but if you start to see black spot, cut them back, remove any damaged stems and leaves---and get that debris off your property—and fertilize to stimulate new growth---you might also want to use a fungicide spray until the new growth matures somewhat to help prevent the disease from coming back. The key word here is “resistant”; they will occasionally succumb to some disease problems.

They may also fall victim to rose slugs in the spring. If rose slugs do enough chewing, they will weaken the plant reducing its ability to flower. Control rose slugs with Bt, a bacterium that is toxic to caterpillars and larvae.

The good news about Knockouts is that they are so durable, if they look really bad in early summer, simply cut them back hard, give them a good dose of rose fertilizer, and they will came right back for you---hopefully without the pest problems that they had before you cut them back.

This principle also applies if you didn’t get them cut back in late winter before they started leafing out. If you want to reduce the size, simply go ahead and cut them back, ignoring all that new growth, fertilize, and watch them come right back…

Knock Out is usually a very healthy rose and will take a lot of abuse. However it is still just a rose and if conditions are right, can get disease problems. We are seeing lots of reports of canker caused by a fungus on Knockouts. This particular fungus is very contagious. What happens is that if a cane is accidently physically damaged, gets too much fertilizer which burns a cane, is situated in poor drainage, gets die back on a cane during the winter or it is damaged when purchased or planted, then this fungus sets in. It can easily be spread by pruning one rose and then using the pruners on another as the pruners should be cleaned with rubbing alcohol. This fungus spreads too rapidly for organic solutions. I would prune the infected plants right down to 6 inches or until the middle of the canes are a pale green/cream with no brown showing. Then wipe the pruners off with the alcohol and cut down another one on the same bush. Just keep doing this until you are satisfied that all the canes on the rose bushes are free of the fungus. And get rid of all the prunings—in a closed plastic bag, off your property. Spray the plants again plus all around the base in case there could be fungal spores there too. During the spring or until it gets warm, make sure you water gently around the bottom of the rose bushes as water on the canes will encourage it to come back. Then when the weather warms up, you should have no more problems as these spores like cool weather.

And, once again, knockout roses are still roses, so they are heavy feeders that need the same fertilizer treatments that other roses do. Begin a monthly fertilization program in early March and continue until August.

Here’s a formula for the first fertilization. Atfer this application, use a rose fertilizer every month.

½ cup Osmocote
¼ cup Nitroform (or other slow-release high nitrogen product)
2 Tablespoons Epsom Salts

The Osmocote is a slow release fertilizer that will provide nutrients all season long. The Nitroform is a high nitrogen fertilizer that will stimulate lots of good, strong vegetative growth to support the blooms, and the Epsom salts will provide magnesium for the blooms.

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fall roses

thanks for that info about the pink speckles on the Ducher rose. It didn't turn brown or slimy, thank goodness.

I've had Angel Face before, she croaked. I loved her scent. Then my nose led me to Blue Girl at HD, which I had for a few years, then she croaked. I'm sticking to OGR's which are more hardy, but I sure miss the scent of those two roses.

Regards..

Jimmy
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