My ligularia Britt Marie Crawford is planted in the natural clay soil, in a slightly elevated soil. The soil in that area was amended over 20 years ago with mulch and compost. Nothing done to it since. We had a really wet spring, and then a really dry summer. I have never watered it in the years I have grown it (except when newly, planted of course). I did notice that it was a bit stressed this year, was smaller than normal and bloomed a month earlier than usual. Mine is in mostly full shade, with part of it growing out where it gets full sun. It's on the north side of my house, and the house shades almost all of it. The plant has grown large enough though, that a few leaves stick out in the sun.
Last spring, I planted another one on the back side of my house, but it was the plain green one. It is south facing, but has a mature cornus mas and a magnolia over top of it. So it will be shaded. But it is pretty dry in there. It made it until fall ok. Sounds like I may want to move it to an area with better soil and more moisture. Not easy to just "tuck in" a plant that takes up 4 feet by 4 feet !!