What would work here?
Zone 5--I'd like to plant something in front of the 3 Arborvitae here. It's hard to tell from the picture, but there is a bit of a slope that's a pain to mow and since this is the view from our deck, I'd like to add some color. Maybe start with something in between and forward of the bushes. I don't want to disturb the roots of the Arbovitae or do anything that would cause a problem,though, so I've been hesitant to start anything on my own. The soil is clay and it gets a mixture of sun and shade throughout the day The sun is sun, but it's not blaring direct sun.