Question
dear Lynnatte, I live south of New Orleans and have problems with Knock out roses. I have (2) separate rows of doubles in my backyard about 40 feet apart and were planted in february this year. one row did fantastic grew and bloomed profusely all summer, The second row barely grew at all and the blooms were about 1/2 the size of the other blooms. The leaves on these would come out and were small and shriveled. The plants never got more than 18" tall where the second row were 4'.
I used systematic sprays and root applications. by september my good row of knockouts started "thinning out" and looking bad.
I cut them all back in late september down to 12" or less.All that was left is stems.They are now starting to produce leaf growth again but some of the leaves are still coming out small and shriveled while the rest of the leaves on the same plant appear normal. None of them seem to be the dark green leaves like you see on newly purchased plants. Both rows were on the same watering system this summer. I have turned the system off the last month but the soil is not too dry. I also have single knockouts in the front yard that are beautiful. They are 2 years old. When they start thinning out and looking bad I cut them back and they regrow wonderfully. are singles more resistant than the doubles? should I swap the doubles for singles? do you think its the heat, if so why doesnt affect the singles? all roses are the red. Can you recommend any literature on the care of knockouts
any help would be appreciated sincerely, s moise  

Answer
I know there is a lot of hype about Knock Out roses but alas they are no different then any other rose and will have the same problems. The only feature that may be a little different is that they are quite hardy and have good disease resistance. However I am getting a lot of problems regarding Knock Out roses doing the same as yours and there seems to be a common thread in all of them. Every gardener has used a systemic spray or even just a three in one type of spray, Knock Outs seem to resent these chemicals and will re-act. This is not to say that the spray is your problem. If you bought the roses from a rose nursery then ignore this but could your roses have a virus problem? Something at the roost level is stopping the plants from growing properly. Did you place some chemical fertilizer in the hole when you planted them? Some roses resent it when the roots get burnt.
It almost sounds like there is something in the soil on the second row that has caused the roots to re-act to it. Can you think of anything that you did to the soil? Even if it was to improve it? From what you have described, it is the roots that are complaining and you are seeing it in the leaves. You have probably checked, but are there any insects on the underside of the leaves such as spider mites?
When a breeder has a hit with a rose they always try to capitalize on it and the Knock Outs are no different. The original is still by far the best of the lot. That is not to say that the doubles can't grow well for you, but it is a fact that they don't bloom as well as the singles or have as much foliage.
On the rose forums I read that Knocks Outs are either very good or people don't like them because they don't do well. Usually if a rose is a good one then most people will praise it no matter where it is grown. It is the same with a poor one but there seems to be a love hate affair with these roses.  Most web sites that talk about the Knock Outs will be all positive as it will be advertising. Gardeners never seem to be allowed to hear anything negative about roses.
Is it possible to give me some more information regarding what is in the spry and about your soil?