I'm looking for smaller alternatives to Big Blue liriope for an edger plant for flower beds. I also like the variegated liriope for its size--that's about the size I want-- but am interested in a solid green form for some of my beds so as not to compete with some of the plantings. But, I want a clumping variety and not an invasive spreader. I've been afraid to buy various apparently smaller cultivars of liriope because I can't tell for sure if they're the invasive groundcover type or which is a clumper that will stay put as an edging plant.

Can someone suggest the right species for this use? Plus other plants that you've found do well as edging.