A clumping, dwarf plant 12-18 inches high, with dense dark blue flower spikes for much of the summer. Bred for more heat tolerance than other Austrian Speedwells, 'Darwin's Blue' is a charming addition to a rock garden or a sunny border. PP 13070. Z. 4-7

This groundcover is covered with light blue flower spikes from late spring to early summer. It will often rebloom in late summer, too. The spreading mat of gray-green foliage will enhance the front of any perennial garden, but it's probably best sited in a rock garden to provide delightful delightful dashes of color. A tough plant which can survive many years if planted in full sun and well-drained soil. Z. 5-8

Veronica is a mainstay of the perennial border, and this introduction from England should fuel a veritable craze for Veronicas. Deep blue-purple spikes are produced over a long period in summer, and the plants are tight and compact—to about 3 feet in flower. PP 18932. Z. 3-7

We were enchanted by this plant as it leafed out in spring with its short, narrow, tapered leaves, followed by dark blue flowers. The spreading mat of rich green foliage will enhance any perennial garden, but it's probably best planted in a rock garden, where it can slither down a crevice or enliven a bare spot among other plants. Z. 4-7