Lavender in Zone 7B — Desert Southwest

Lavender is a fantastic choice for your Desert Southwest garden. Its fragrance is wonderful, you can use it in so many ways, and watching it thrive in our arid climate is really satisfying. Plus, the bees absolutely love it!

While our extreme heat and alkaline soil can be tough, Lavender is surprisingly well-suited to our climate. With our long growing season – around 245 days – you'll have plenty of time to get it established and enjoy its beauty.

Starting Lavender from seed indoors is possible, but it can be a bit slow and tricky. Honestly, for most of us here in the Desert Southwest, it's easier to buy starter plants. But if you want to give it a try, start your seeds indoors from mid January through early February. That's about 10 weeks before you'd want to put them outside.

Use seed trays with good drainage, a heat mat to keep the soil around 70°F, and a grow light. Bottom watering helps prevent damping off, which can be a problem. Remember, our spring can come early, so keep an eye on the weather!

Transplant your Lavender outdoors from late March through mid April, after the last expected frost. Before you plant, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space your plants 12-18 inches apart to give them room to grow. The weather during this time can be unpredictable, so watch out for late cold snaps or unexpected heat waves. For reliable results, I recommend buying established starter plants from a local nursery. They're already adapted to our conditions.

Lavender thrives on neglect, which is perfect for us Desert Southwest gardeners. Overwatering is its biggest enemy, especially with our heavy monsoon rains. Remember, it's drought-tolerant and prefers dry, poor soil.

During the active growing season (spring and fall), water deeply every 2-3 weeks, or when the top 2 inches of soil are dry to the touch – use the "finger test". Give established plants about 1 inch of water per week. Water at the base of the plant to avoid wetting the foliage, which can lead to fungal problems in our occasional humid monsoon conditions.

In the extreme heat of summer, you might need to water a little more often, but be careful not to overdo it. During the winter months, you probably won't need to water at all unless we have an unusually dry spell. Signs of underwatering include drooping leaves and stunted growth. Overwatering can cause yellowing leaves and root rot. A light layer of gravel mulch can help improve drainage and prevent soil from splashing onto the plant.

Pruning is important for keeping your Lavender healthy and productive. After the flowers fade, usually from late June through early August, deadhead the spent blooms. This encourages new growth and keeps the plant looking tidy.

Shape the plant into a nice mound by cutting back about one-third of the growth. Be careful not to cut into the old wood (the woody stems at the base), because it won't regrow. In late fall, after the first frost (around mid- November in the Desert SW), give the plant a light trim to remove any dead or damaged growth.

You can expect your first Lavender harvest from late June through early August, about 90 days after transplanting. 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 fully colored but not fully open. Cut the stems as long as possible, leaving a few inches of foliage on the plant. To dry your Lavender, gather the stems into small bundles and hang them upside down in a cool, dark, and dry place. Keep harvesting throughout the season to encourage more blooms. Even as the first frost approaches in mid- November, you can still harvest any remaining flowers.

Lavender is generally easy to grow, but here are a few problems to watch out for in the Desert Southwest:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and a mushy base to the plant.
• What causes it: Overwatering, poor drainage, and heavy soils. In our region, this can be exacerbated by heavy monsoon rains.
• How to fix/prevent it: Plant in well-draining soil, water sparingly, and avoid planting in areas that stay wet. Amend heavy clay soils with compost or gravel.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and dieback of stems.
• What causes it: A fungal disease that thrives in warm, humid conditions. While we're arid, monsoon season can create enough humidity for this to take hold.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning regularly. Remove and destroy any infected plant material.

Phytophthora Root Rot

• What it looks like: Sudden wilting, yellowing foliage, and dark lesions on the roots.
• What causes it: A soilborne pathogen that thrives in wet conditions. Overwatering and poor drainage are major contributors.
• How to fix/prevent it: Ensure good drainage, avoid overwatering, and use disease-free plants.

Desert Southwest Specific Challenges: Our extreme heat can stress Lavender, making it more susceptible to problems. Arid humidity means good drainage is critical to avoid root rot. Even though we get monsoon rainfall, it's sporadic and intense, so careful watering is key.

Lavender makes a great companion plant for several herbs and flowers in our Desert Southwest gardens. Rosemary, thyme, and sage all share similar growing requirements – full sun and well-drained soil – and their aromatic oils can help deter pests. Roses also benefit from being planted near Lavender, as it can help protect them from aphids. Avoid planting mint near Lavender, as it's a vigorous grower that can quickly take over and compete for resources.