Ajuga is one of the best known and most useful groundcovers, suiting many different situations and color schemes.  Plants spread by runners and soon create a thick groundcover carpet of foliage.  ‘Princess Nadia’ is a reblooming Ajuga that displays intense purple-blue flowers in early spring and then again in summer.  When the plant is not in bloom, the tri-colored foliage in cream, green and pink adds color.  Easy to maintain.