Thyme Leaf Speedwell | If you are needing a short, and we mean short, ground cover for the rock garden, stone steps, rock walls, or trough garden look no further. This very cool little Veronica might get to 1/2" tall and will make a nice wide mat over time, plus it is evergreen. Definitely not a plant for the wet areas but in the right spot (dry areas) it is super hardy and really cool. At Yew Dell we have it planted in the raised area between the Glass House and Rock House. The soil in that rasied area is basically just pea gravel and it loves it there. Blue to bright blue flowers open in late spring.