Those are so cool!

Wow - just stunning! I'm jealous. :-) I finally found a spot where I think mine will live happily, but now I need some patience while they grow.

Is there anything special you'd recommend as far as care?

Is this one of the plants that is a real runner or is somewhat restrained in its habits in your experience? I love those big round leaves!

Water is what these plants NEED. You can't see it in the picture but there's an extension pipe, attached to a nearby downspout, running under the path to deliver lots of water directly to the base of the near astilboides. The neighbour next door directs one of their downspouts at the other one. I have a couple of other astilboides elsewhere in the backyard that are pathetic puny things because they're not getting enough water. I need to move them somewhere more suitable.

These two were planted in 2007. The clumps have got bigger - produce more leaves - but they haven't really spread. Water is the limiting factor I think. They might spread a bit more at the edge of a pond perhaps but otherwise they will stay close to where it's wet. I doubt they'd ever be a serious spreading problem in normal garden conditions. They'd be a good plant to plant near any downspouts from the eaves. These ones get morning shade and some afternoon sun.