I didn't really plan on blogging about the Knockout Rose this morning. But since it is the topic on The Garden Rant, on which I felt compelled to make a comment, I guess I should just deal with it now!
The introduction of the single red Knockout is now ten years old. It has become one of the most popular landscape roses ever. I planted eighteen single red Knockout roses a little over six years ago. I will bet I have no more than four of the original left. After the first year and a few losses, I asked a Jackson and Perkins rep that I met at a local plant show what was going on with the Knockout. He stated that it was never meant to be totally hardy in Zone 5 and that I should replace them with the newly introduced double Knockout. So, this is what I did. As each original Knockout succcumbed I replaced it with a double.
Some I replaced with pink, or single yellow, or Rainbow Knockout. Rainbow is a single, but it is the hardiest of all. It begins as a pink, morphs into a combination of yellow pink and slowly fades to a pale pink. It will bloom without being pruned, but I do prune it for looks. The blooms stay on the bush until November. I now have more Rainbow Knockouts woven through my landscape than the red single or double Knockout.