"Feet in the shade, heads in the sun"...yes, that's what clematis love. I am always eager to learn how the original species grows...sometimes that sort of information gets lost over the centuries. Clematis are woodland edge plants....in the wild, they live at the margins of forests, so they like compost soil, something to climb up, and shade around them so they can reach up for the sun. I was actually surprised to learn that lilies are woodland plants...I've always just been told "plant in full sun" and its really better for them to get some dappled shade. Live and learn.
