Hi, experts. I am hoping that you can tell me what I did wrong, or if I should just give up on heucheras.

I have an area with dappled shade under some oak and cypress trees, and I put some heucheras with burgundy-colored leaves (sorry I don't know the exact name) in the area. Well, they all croaked. I have some of the lime green ones that are hanging in there, but not looking super happy either.

I do live in a hot area, but these guys were not exposed to direct sun, and we've had the afternoon rains lately, so I don't see how they are not getting enough water.

Does anyone have an idea of something I can do to keep the remaining lime green ones?

Thanks!