I checked out the knock out roses in front of the grocery store today. The double cherry knockout was prettier than the other red and pink ones. I didn't detect scent, but the roses were very stressed and neglected in their little pots by the entrance.
The knockout breeder, Radler, keeps coming up with new hardy roses. Knockout fans may want to search for other roses bred by him.
I didn't get any knockouts, but the cutest red and white striped mini rose hopped intomy cars somehow.
