Pink Texas Skullcap is a tiny superhero. Technically is an herb. Here at home is evergreen. I believe you can create a mini edge with it. But it will look more like an edge ground cover. Great for xeriscaping. And best of all, from late spring to summer it blooms red flowers similar to those in snapdragon plants(in a tiny version of course).
I reproduced this plant from a potted skullcap. I heard it grows well on clay soil. The potted skullcap I got is in rich potting soil mix. The one in the picture is growing in clay soil, and growing strong.