Lavender in Zone 8B — Desert Southwest

Lavender is a fantastic addition to any Desert Southwest garden. Its fragrant blooms and silvery foliage thrive in our sunny, arid climate, and the flowers are perfect for everything from culinary uses to aromatherapy. Plus, the bees absolutely love it!

While the extreme heat and alkaline soil here present some challenges, Lavender is surprisingly well-suited to our region, especially if you plan your planting and watering carefully. With our long 279-day growing season, you'll have plenty of time to enjoy its beauty.

Starting Lavender from seed indoors is possible, but be warned, it can be a slow and somewhat finicky process. If you're patient and enjoy a challenge, go for it! Otherwise, buying established starts from a local nursery is often the easier, more reliable route.

If you want to start your own seeds, aim for late December through mid January, roughly 10 weeks before you plan to transplant outdoors. Use seed trays with a well-draining seed starting mix, and provide warmth and plenty of light – a heat mat and grow lights will be your best friends. Bottom watering helps prevent damping off, which is crucial when starting seeds this early in our very-early spring.

Transplanting Lavender outdoors should happen mid March through early April. Before you commit them to the garden, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Desert Southwest's intense sun and temperature swings.

Plant your Lavender seedlings 12-18 inches apart in well-draining soil. Keep an eye on the weather forecast – late frosts can still happen, so be prepared to cover your young plants if necessary. Honestly, though, buying established starts is the easiest way to guarantee success and avoid the slow growth of Lavender from seed.

Watering is where Desert Southwest gardeners can easily go wrong with Lavender. Remember, this plant is drought-tolerant and hates wet feet. Overwatering is a surefire way to kill it.

During the cooler months of spring and fall, water deeply but infrequently – aim for about 1 inch of water per week, only when the top 2 inches of soil feel dry to the touch (the finger test). In the extreme heat of summer, you might need to increase watering slightly, especially for young plants, but still be very cautious. During the monsoon season, rely on the rain as much as possible and reduce supplemental watering accordingly.

Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our arid climate. Signs of overwatering include yellowing leaves and a mushy stem base. Underwatering will cause the leaves to wilt and turn brown. A light layer of gravel mulch around the base of the plant can help improve drainage and prevent soil from splashing onto the foliage.

Pruning is essential for keeping your Lavender plants healthy and productive. After the first flush of flowers in early summer, deadhead the spent blooms and lightly shape the plant into a mound. Cut back about 1/3 of the growth, but be careful not to cut into the old wood, as Lavender doesn't typically regrow from there.

Continue deadheading throughout the flowering season to encourage more blooms. In late fall, after the last flowers have faded and before our first frost around early December, give your Lavender plants a final light pruning to remove any dead or damaged growth. This will help them overwinter successfully.

Your first Lavender harvest should be ready sometime in early June through late July, depending on the variety and the weather. The best time to harvest is in the morning, after the dew has dried but before the sun gets too hot. Look for flower stems where the buds are colored but not fully open – this is when the fragrance is most intense.

Cut the long stems with sharp scissors or pruners, leaving several inches of foliage on the plant. Gather the stems into small bundles and tie them together with twine. Hang the bundles upside down in a cool, dark, and dry place to dry for several weeks. Continue harvesting throughout the summer to encourage more blooms. As the first frost approaches in early December, harvest any remaining flowers to enjoy their fragrance indoors.

Here are some common problems you might encounter growing Lavender in the Desert Southwest:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, stunted growth, and a mushy stem base.
• What causes it: Overwatering, poor drainage, and heavy soil. In our region, this is often due to overzealous watering schedules that don't account for our arid climate.
• How to fix/prevent it: Ensure excellent drainage by planting in well-draining soil and avoiding overwatering. Water deeply but infrequently, allowing the soil to dry out between waterings. Consider raised beds or amending heavy clay soil with gravel.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and a general decline in plant health. The stems may develop dark lesions.
• What causes it: A fungal disease that thrives in humid conditions and poorly draining soil. While we have low humidity, monsoon moisture combined with poor air circulation can create favorable conditions.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning to remove dead or crowded growth. Avoid overhead watering. Remove and destroy infected plants to prevent the spread of the disease.

Phytophthora

• What it looks like: Similar to root rot, with yellowing leaves, wilting, and a mushy stem base. Phytophthora can also cause root lesions and a general decline in plant vigor.
• What causes it: A soilborne pathogen that thrives in wet conditions. Poor drainage and overwatering are major contributing factors, especially during our monsoon season.
• How to fix/prevent it: Improve drainage by amending the soil with organic matter and planting in raised beds. Avoid overwatering and ensure good air circulation. Use disease-free plants and avoid planting Lavender in areas where Phytophthora has been a problem in the past.

Desert Southwest Specific Challenges: Our extreme heat can stress Lavender plants, making them more susceptible to disease. The arid humidity means that good air circulation is critical to prevent fungal problems, especially during the monsoon. Be extra vigilant about drainage and avoid overwatering, as these are the biggest threats to Lavender in our region.

Lavender thrives alongside other Mediterranean herbs that share its love of sun and well-drained soil. Rosemary, thyme, and sage are excellent companions because they attract beneficial insects and deter pests, plus they enjoy similar growing conditions. Roses also make good companions, as they appreciate similar soil and watering conditions and their contrasting colors create a beautiful visual display.

Avoid planting Lavender near mint. Mint is an aggressive grower that can quickly outcompete Lavender for resources. Plus, mint prefers moist soil, which is the opposite of what Lavender needs to thrive.