Lavenders want well drained soil, good air circulation, and as much sun as possible to promote flower production. Lavenders prefer neutral to alkaline soil. In humid climates, coarse sand worked-in around the crown will help the plant dry out. Keep weeds down to prevent sources of wetness and avoid wetting the lower leaves, which may encourage disease. Lavenders require no feeding, though an occasional dressing of low-nitrogen organic fertilizer will make your plants happy. If you are growing lavenders in containers, a spring feeding of a slow-release fertilizer will be helpful. Also, lavender in containers will dry out faster than in the ground, so keep an eye on them.
Tips for Pruning Lavender
Lavender can be pruned in the early spring or in the fall (not too late so as to give plants time to harden off before winter). Generally speaking, trim plant by one third, keeping the typical mound shape of the plant. If you do not plan to harvest the flowers, then a light pruning just after flowering, will be sufficient to promote new growth. Cut each flower stem back to the first or second pair of leaves. Pruning old, woody lavenders can be tricky. Some growers recommend pruning the plant down to the base after flowering if there is evidence of new growth. The plant may continue growing anew or may die. If you are sentimental, take a cutting from the plant before pruning, just in case. Other growers recommend taking a three year approach to revitalizing old, woody plants. Cutting the plant back in spring and fall by 1/3. Also, cutting out any woody stems that are dead. Again, there are no guarantees. The best plan is to begin a regular pruning regimen with your plants, minimizing woody growth.
Tips for Harvesting and Drying Lavender
Lavender blossoms should be harvested when only one or two buds have opened. Harvest in the late morning after a few days of dry, warm weather. Tie up small bundles with rubber bands. Hang upside down in a dark room with good air circulation. Lavender flowers will fade in color if exposed to sunlight.