Sherry, I respectfully disagree with you, at least in part. With few exceptions, most of us here are gardeners not botanists. Based on our experience, we can fill out the database with what we know. For example, although not typically listed for more than dappled shade, I know that Microbiota decussate 'Prides' grows in close to complete shade for that is where I have it and it continues to do well. However, for me to be able to attest to the fact that it is rated from zone 2 to 7, I must rely on the research I've done, and not on my experience. The thing is, many of us are good researchers when it comes to plants, and we do well to share that research here.
