Creeping Thyme T. serpyllum. Creeping thyme is an ornamental. From a tiny clump of little seedlings comes a spreading mat of scented foliage covered with pink flowers. Plant Creeping Thyme seeds for excellent coverage and easy use in rock gardens. This is a mat forming herb that grows to maximum heights of 15cm (6") and blooms May to August. Grow in full sun, in well drained soil, with moderate to low water. Use in rock or herb gardens, as an edging along paths or as a ground cover. Plant in Zones 4-9. Creeping Thyme is a slow growing plant with dust-like, tiny seeds. To fill in a larger area more quickly, try sowing the seeds sparsely into a 128-cell Plug Insert, and create as many seedlings as possible for later transplanting. The seedlings may have to grow in the flat for the first season, but you will end up with better, more even coverage.