Good question, Bob. I'll be watching this thread to see the replies. Let us know what works for you.

Like you, I've tried toad lilies a couple of times and in different locations, but they did not live beyond their first summer.

Maybe keeping these two in pots for a season will make it easier to keep them under observation.

I have had Toad Lilies for three years in a shady, damp spot in Savannah. They have multiplied, but I would not consider them invasive where I have them.

I have a friend who's had them in her garden for forever, I think, and they are NOT invasive. Her parents brought them back from Japan in the sixties, I believe.

I guess it depends on your soil. In my clay based soil toad lilies are very invasive, I have to thin them every 3 months and took out most of them where they invaded othjer plants like the roots of my roses.