Thymus Serpyllum seeds to grow a wonderfully hardy ground cover directly in the garden or border! Just 8 inches tall, Creeping Thyme ground cover plants are completely covered in 1/4 inch bells of carmine-pink for months on end. Butterflies love it and so will you! It is lemon-scented, with fine dark green foliage and slightly hairy leaves. Creeping Thyme will spread to 18 inches in width in no time at all.