The small spaces between rocks, and stone pathways are tough area to grow anything except weeds, but here are a few plants that thrive between the cracks and crevices.
Creeping Thyme (Thymus serpyllum): Excellent for pathways, grows flat and tolerates foot traffic. Likes well-drained soil. Soft fuzzy Appearance. Herbaceous Perennial, Fragrant, Pink flower, Sun/Part Shade, Deer Proof, Attracts Bees. USDA Hardiness Zones 4 to 9.
Wooly Thyme (Thymus pseudolanuginosus): Durable plant perfect for filling in between stepping stones, or rock gardens. Soft foliage creates a low, lush mat with pink flowers. Herbaceous Perennial, Attracts Butterflies & Bees, Sun/Part Shade, Drought Tolerant/ Water Wise Groundcover, Deer Proof. USDA Hardiness Zones 5 to 8.
Blue Star Creeper (Isotoma fluviatilis): A wonderful creeping perennial for filling in. Use between stepping stones, under shrubs, in rockery, around ponds. Tiny green leaves form a dense, low mat ½ inches high. Produces tiny light blue star-shaped flowers which cover the plant late spring into fall. Perennial, Evergreen, Full Sun/Part Shade, Tolerates Foot Traffic, Like Moisture, Deer Proof. USDA Hardiness Zones 5 to 9.