Lavender: Create a thick hedge by making your ridge 24 inches wide and set lavender plants in two rows 12 inches apart. Instead of planting in parallel rows, stagger plants so plants of one row are halfway between plants of the other row. Lavender needs good air circulation to prevent disease. Keep your hedge weed free and avoid locating your hedge too close to other plantings.
How to Prune Lavender - Cut back in Late Winter or early spring as close as possible to old wood without cutting into the old wood; leave a few healthy leaves above the brown stems (plants won't produce new shoots from old wood). In Late Summer after flowering, remove all the old flowerheads to prevent plant from using energy to make unwanted seed.