Maurice, I'm greatly indebted for you outlining a clear way to set up an experiment to find out how my DL fans are faring in my gardens!
Since there is so much stress on them it is worth it for me to prepare and do such a test. I'll have to start, I think, with ordering a number of fans from one cultivar next spring so that a larger number of similarly sized fans from the same clump and field will start out in the mix (none are that established here yet). I'm bookmarking your excellent description for reference as I get it underway next year - thank you so very much!
And, Natalie and Pam, lol, I too wonder if my furnace blasted plants wouldn't march right out of my yard if there wasn't fencing around the perimeter!
I'm glad to say mine don't have enough sand to burrow under and sneak on down to the coast ... or ... huh ... maybe that's where my Magician's Apprentice fan disappeared to last year!