6720-Lavender. A strain of English lavender with a compact, bushy habit. Nice range of bloom colors, from pale blue to dark violet. Usually begins flowering in the second year. Hardy in Zones 5-8, but can survive Zone 4 winters when mulched or grown in a south-facing location.Plant lavender in full sun and well-drained soil (add organic matter to improve heavy soils). Water plants deeply but infrequently, when the soil is almost dry. Prune in early spring or at harvest time. For low-growing varieties, trim back foliage 1 to 2 inches.