Thanks for the info on Monrovia's plant list inaccuracies. I will see if I can get them to fix that. Unfortunately we at the Q&A service don't have information on which plants are sold at the many retailers who carry Monrovia plants. Due to the seasonal nature of Monrovia's plants and limited quantities on many varieties, each garden center will offer a different array of plants. Not all plants are available in all regions at all times. Your best bet is to contact a local retailer that you know will carry Monrovia plants and see if they can get the plants you are interested in.
All that said, Knock Out is pretty easy to find in a wide variety of nurseries. I suggest you try starting with the Cornelius Nurseries there in the Houston area. They carry a wide variety and should have it.
Thanks for the question. Please stop in again soon!
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