Lesser celandine strategies
We have a fairly large (100sf total) infestation of lesser celandine. I’ve been told to dig it out (I’ve contacted the extension before, and spoken to other professional gardeners), and I’ll dig it out if I have to, but- I’ve been planning on replacing our grass lawn with either clover or some native ground cover/wildflower, phlox/sedge etc. mess anyway. So I need to kill the lawn. If I tarp the whole thing, with black black plastic, until, say, October, the grass will die, but will it take out the little bulblets as well?
No, that will probably not kill the bulblets. When their spring foliage dies down, they go dormant anyway.
Does it still have green foliage? Though we are loathe to do so, this may be a case where we'd recommend using glyphosate--but there must be growing green foliage to absorb it, otherwise it will not work and go down into the roots and bulblets.
If you dig it out, you'll have to remove the top few inches of topsoil entirely, in order to get all the bulblets. This is not impossible with 100 square feet total.
Here is our page on lesser celandine, which has good links, too: https://extension.umd.edu/hgic/topics/groundhogs Weeds Gone Wild is a very thorough website.