Lavenders (Lavandula spp.) evoke images of Mediterranean gardens, but that doesn't keep them from thriving under the hot desert sun. Arizona's arid climate and rocky soils suit lavenders well, from the desert lowlands to high-desert mountains and Mediterranean-style foothills. For Southwest gardeners, lavenders reign as simple-to-grow, low-maintenance garden standards.
Sun, Soil and Circulation
Lavender's most prolific blooms and aromatic oils come with full sun. But if you garden in Arizona's hottest regions, especially urban heat islands, avoid planting lavender near west-facing walls. Filtered shade during midday is a better choice. In all other areas, give lavender at least six to eight hours of direct sun daily.
Excellent drainage is essential to lavender health and longevity, and most Arizona soils oblige. Rocky, nutrient-poor and alkaline, the state's natural soils are similar to lavender's native habitat. Lavenders do well in improved garden situations, too, as long as soil is well drained.
When spacing plants, keep good air circulation in mind. Common Arizona lavenders regularly spread 3 feet wide or more. Allow for mature plant size and at least 6 to 8 more inches between plants.
Water in the Desert
Getting lavenders established in Arizona demands frequent watering while plants settle in. Planting is best done in fall and winter, so roots develop before summer comes. Gravelly Arizona soil dries out quickly, so monitor new plants closely.
Once lavenders are established, water deeply once per week or less. Container-grown lavenders need watering daily in summer. Root and stems rot due to overwatering are common Southwest problems -- when gardeners respond to soaring summer temperatures with too much water. Yellow lavender leaves warn you're watering too much. Always use containers with drainage holes to help with the problem.
Kept on the dry side, lavenders stay more compact and dense. Hot, arid conditions also increase the concentration of aromatic oils in foliage and flower heads.
Fertilizer and Flowers
Established lavenders rarely need fertilizer. Arizona's nutrient-poor soils enhance blooms and the aromatic oils. Unless your plants shows signs of ill health, don't fertilize. Too much fertilizer causes lanky, weak growth and leaves lavenders susceptible to pests and disease.
Depending on the species, Southwest lavenders may bloom from fall through spring into summer. High heat and the region's monsoon rains often put flowering Arizona lavenders on hold.
Remove flower heads regularly to encourage continued blooms through the growing season. Deadhead spent flowers or harvest lavender wands for drying or bouquets. Use sharp bypass pruners, and sterilize blades with spray household disinfectant before and after you prune.
Lavenders for Arizona
Arizona is diverse in its climates and plants. The state spans U.S. Department of Agriculture plant hardiness zones 4b through 10b. Some regions see winter lows of minus 25 degrees Fahrenheit, while other stay above 35 F year-round. Matching lavenders to your climate important.
Spanish lavenders (Lavendula stoechas, USDA zones 8 through 11) are low-desert and urban favorites, with showy rabbit-ear blooms in deep purple. French lavenders (Lavandula dentata, USDA zones 8 through 11) produce extended Arizona blooms -- nearly year-long. English lavenders (Lavandula angustifolia, USDA zones 5 through 11), the hardiest of the three, prefer the state's cooler, higher elevations.