Lavender reaches maturity and full productivity in 3-5 growing seasons. The leaves and flowers of lavender contain strong aromatic essential oils that act as a natural repellent for deer, rabbits and other pests. These same oils attract butterflies, bees and other pollinators to the garden. Lavender can live 10-15 years or longer with good post-planting care.
During their first growing season young plants should be well watered to encourage good root development prior to winter. In the hot summer months water several times per week based on plant and garden conditions. For example, in the Palouse region we water every 2nd or 3rd day during our long hot dry summers. Once lavender is established in the 2nd or 3rd year the plants are drought tolerant and don’t need frequent watering. Plants, however, should be deeply watered once every week or two weeks depending on dryness and when flowering. Remember, lavender thrive in well-drained soils and do not like their roots in standing water which can cause root rot.
Lavender thrive in low to moderately fertile soils, and therefore, should require little or no fertilization. In fact, fertilized lavender tend to have fewer flower blooms and greater vegetative growth. In addition, lavender that is over-fertilized and over-watered has less intense fragrance by lowering the concentration of essential oils. Both watering and fertilization should be stopped in September to promote lavender hardening prior to the onset of winter, which will lessen the occurrence of winter damage and mortality.
Harvesting flowers early in the growing season promotes air circulation, new branch growth and a second bloom later in the summer. We harvest at the first sign of flowering to maximize the amount of essential oils in the buds. If plants are harvested near or at full flowering this will lessen the chance of a second bloom. Every August or September lavender should get a heavy pruning in preparation for winter. Branches are cut leaving 2 inches of green foliage above the woody stems. The pruning should result in a mound shaped crown to prevent winter damage. Dead and low hanging branches should also be cut to promote better air circulation and prevent disease This annual pruning slows down woody stem growth, promotes new stem growth next spring which produces better foliage and flowering, and maintains a dense mounded form.
Even when everything is done correctly the unexpected can happen. Lavender does well when the weather cooperates, but losing plants following harsh winters or delaying the onset of flowering during cold wet springs is not uncommon.