Lavender in Zone 7A — Desert Southwest

Lavender is a fantastic addition to any Desert Southwest garden. Its calming fragrance, beautiful purple blooms, and culinary uses make it a versatile and rewarding plant. Plus, it thrives in our hot, dry climate, adding a touch of the Mediterranean to your yard.

While the extreme heat and alkaline soil of the Desert Southwest can pose challenges, with careful planning and proper techniques, you can absolutely grow thriving lavender. Our long, 230-day growing season gives you ample time to establish these plants and enjoy their benefits.

Starting lavender from seed indoors is possible, but it can be slow and a bit tricky. If you're up for the challenge, begin in late January through mid February, giving the seedlings about 10 weeks to develop before transplanting. Use seed trays with a well-draining seed-starting mix, and provide consistent warmth and bright light.

Bottom watering is especially helpful for lavender seedlings, as it prevents damping off and encourages strong root growth. Given our very-early spring character, it's important to keep a close eye on the weather and be prepared to adjust your transplanting schedule if needed. Honestly, for more reliable results, consider buying established starts from a local nursery.

Transplant your lavender seedlings or starts outdoors in early to late April, after the last expected frost. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. Space your plants 12-18 inches apart to allow for good air circulation.

Keep an eye on the forecast during this time. The Desert Southwest can still experience temperature swings in early spring, so be prepared to protect your young plants if a late frost threatens. Remember, buying starts often gives you a head start and a more robust plant ready to handle our conditions.

Lavender is very drought-tolerant once established, which makes it perfect for our Desert Southwest climate. Overwatering is a much bigger threat than underwatering, so err on the side of dryness. The key is to provide deep, infrequent watering, allowing the soil to dry out completely between waterings.

During the cooler spring and fall months, you may only need to water every 2-3 weeks, depending on rainfall. In the extreme summer heat, increase watering to about once a week, providing about 1 inch of water each time. Use the finger test – if the top 2 inches of soil are dry, it's time to water. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our arid climate.

Signs of underwatering include wilting or drooping leaves, while overwatering can lead to yellowing leaves and root rot. A light layer of gravel mulch around the base of the plants can help improve drainage and prevent soil from splashing onto the leaves during our monsoon season.

Pruning is essential for maintaining the shape and vigor of your lavender plants. Deadhead spent flowers throughout the growing season to encourage continued blooming. After the main flowering period, typically in late summer, prune the plant back by about one-third, shaping it into a neat mound.

Be careful not to cut into the old wood, as lavender doesn't readily regrow from there. In the Desert Southwest, with our first frost around early November, avoid heavy pruning too late in the season. This can stimulate new growth that won't have time to harden off before winter.

You can expect your first lavender harvest in early July through mid August, about 90 days after planting. The best time to harvest is in the morning, after the dew has dried but before the heat of the day sets in. Look for flower stems where the buds are showing good color but haven't fully opened yet.

Cut the stems as long as possible, leaving several inches of foliage on the plant. To encourage continued production, harvest regularly throughout the blooming season. As the first frost approaches in early November, you can harvest any remaining flower stems to dry and use indoors. Tie the stems into small bundles and hang them upside down in a cool, dry, dark place to dry completely.

Here are some common problems to watch out for with Lavender in the Desert Southwest:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting despite adequate moisture, and a general decline in plant health. The roots will appear brown and mushy.
• What causes it: Overwatering, especially in poorly draining soil. Our monsoon rains can also contribute to root rot if the soil doesn't drain quickly enough.
• How to fix/prevent it: Ensure excellent drainage by planting in raised beds or amending the soil with plenty of gravel or perlite. Water deeply but infrequently, allowing the soil to dry out completely between waterings. Avoid overhead watering.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and eventual death of the plant. This disease is caused by a fungus.
• What causes it: This fungal disease thrives in warm, humid conditions. Even though we have arid humidity, periods of monsoon moisture can create favorable conditions for the fungus to spread.
• How to fix/prevent it: Ensure good air circulation around your plants by spacing them adequately. Avoid overhead watering. Remove and destroy any infected plants to prevent the disease from spreading.

Phytophthora

• What it looks like: Similar to root rot, with yellowing leaves, wilting, and eventual death of the plant. Phytophthora is a soilborne water mold.
• What causes it: This water mold thrives in wet, poorly drained soils. Like root rot, it's exacerbated by overwatering and our monsoon season.
• How to fix/prevent it: Improve soil drainage by planting in raised beds or amending the soil with gravel or perlite. Avoid overwatering and ensure good air circulation. Use disease-free plants and avoid planting in areas where Phytophthora has been a problem in the past.

Desert Southwest Specific Challenges: The extreme heat of our summers can stress lavender plants, making them more susceptible to disease. The arid humidity means that good air circulation is crucial to prevent fungal problems. And while lavender is drought-tolerant, it still needs adequate water, especially during the hottest months. Be sure to monitor your plants closely and adjust your watering schedule as needed to ensure their health and survival.

Lavender thrives when planted near other Mediterranean herbs that share its love of well-drained soil and full sun. Rosemary, thyme, and sage are excellent companions, as they attract beneficial insects and repel pests. Roses also make good companions, as they appreciate similar growing conditions.

Avoid planting lavender near mint, as mint's aggressive growth can quickly overwhelm the lavender and steal its resources. Mint also prefers moist soil, which is the opposite of what lavender needs to thrive.