Lavender in Zone 6A — Mountain West

Lavender is a fantastic addition to any Mountain West garden. The fragrance is wonderful, the flavor is unique, and the satisfaction of growing your own herbs in our challenging climate is unmatched. Plus, those cool nights even in summer really concentrate the essential oils, giving your lavender an extra boost of aroma and taste.

Our high altitude, intense sun, and alkaline soil can make gardening tricky. But with a little planning, you can absolutely grow lavender here. Our short season of about 153 days means starting early and choosing the right varieties is key.

Starting lavender from seed indoors is possible, but it can be slow and a little finicky. Since our growing season is short, you'll want to give your plants a head start by sowing seeds indoors from late February through mid March, about 10 weeks before you plan to transplant them outside.

Use seed trays with a well-draining seed starting mix. Keep the soil consistently moist (bottom watering works great) and provide plenty of light – a grow light is almost essential, given our late spring starts here in the mountains. Aim for a warm environment, around 70°F, for germination.

Transplanting lavender outdoors should happen after the last expected frost, typically from mid May through early June. Before you plant, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler nights we often experience.

Space your lavender plants 12-18 inches apart in a sunny spot with well-draining soil. Keep an eye on the weather forecast around transplant time. A late frost or hailstorm can set back your young plants, so be ready to cover them if necessary. Honestly, for reliable results, many of us Mountain gardeners prefer to buy established lavender starts from a local nursery.

Lavender thrives on neglect, which is perfect for our dry Mountain West climate. Overwatering is a much bigger threat than underwatering. Remember, lavender is very drought-tolerant and prefers well-drained, even poor, soil.

During the growing season, water deeply but infrequently. Use the "finger test" – stick your finger about 2 inches into the soil near the base of the plant. If it feels dry, it's time to water. Aim for about 1 inch of water per week, depending on rainfall. Water at the base of the plant rather than overhead to avoid creating humid conditions around the foliage, especially considering our low humidity.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can lead to yellowing leaves and eventually root rot. 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 maintaining healthy and productive lavender plants. The goal is to encourage new growth and prevent the plant from becoming too woody.

After flowering, typically from mid August through late September, deadhead the spent blooms and shape the plant into a neat mound. Cut back the stems by about one-third, being careful not to cut into the old wood, as lavender doesn't readily regrow from there. As the first frost approaches in early October, stop pruning to allow the plant to harden off for winter.

You can expect your first lavender harvest from mid August through late September, 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 intense.

Look for flower stems where the buds are showing good color but haven't fully opened yet. This is when the essential oils are most concentrated. Cut the stems as long as possible, leaving several inches of growth on the plant. To encourage continued production, harvest regularly throughout the blooming season.

As the first frost approaches, harvest any remaining flower stems, even if they aren't fully mature. You can dry them indoors to enjoy the fragrance throughout the winter. Hang the cut stems upside down in small bundles in a cool, dark, and well-ventilated place until they are completely dry.

Even in our dry climate, lavender can face a few problems. Here are three to watch out for:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting even when the soil is moist, and a general decline in plant health.
• What causes it: Soggy soil that deprives the roots of oxygen. This is often caused by overwatering, poor drainage, or heavy clay soil.
• How to fix/prevent it: Ensure your lavender is planted in well-draining soil. Water only when the top 2 inches of soil are dry. Consider adding gravel or sand to improve drainage.

Shab Disease

• What it looks like: Stunted growth, distorted or discolored foliage, and a general lack of vigor.
• What causes it: A fungal infection that thrives in humid conditions.
• How to fix/prevent it: Provide good air circulation around your plants by spacing them properly and pruning regularly. Remove and destroy any infected plant material.

Phytophthora

• What it looks like: Rapid wilting, browning of leaves, and dark lesions on stems near the soil line.
• What causes it: A soilborne pathogen that attacks the roots.
• How to fix/prevent it: Improve soil drainage and avoid overwatering. Use disease-free plants and practice good sanitation.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity actually work in lavender's favor, reducing the risk of fungal diseases. However, our alkaline soil can be a challenge. Amend your soil with compost to improve drainage and lower the pH slightly. Also, remember that intense sun can stress young plants, so provide some afternoon shade during the first few weeks after transplanting.

Lavender makes a great companion plant for several herbs and flowers. Rosemary, thyme, and sage all thrive in similar conditions – full sun, well-drained soil, and low water – creating a harmonious and fragrant garden bed. Roses also benefit from being planted near lavender, as the lavender helps to repel aphids and other pests.

Avoid planting lavender near mint. Mint requires consistently moist soil and can quickly spread and outcompete lavender for resources. These contrasting needs make them poor companions.