Lavender in Zone 3B — Mountain West

Lavender is worth growing here in the Mountain West! The intense sun and cool nights concentrate the fragrance and flavor, making it exceptional for culinary uses, crafts, or just enjoying in your garden. Plus, it's a beautiful, drought-tolerant plant that thrives in our alkaline soil.

Our short growing season and occasional hail can be challenging, but with careful timing, you can absolutely grow lavender. Starting indoors and choosing the right varieties will give you a head start to make the most of our 108-day season.

Starting lavender from seed indoors is possible, but let's be honest, it can be tricky. If you want to try, start in late March through mid April, giving the seedlings about 10 weeks to get established before transplanting. This helps them mature enough to withstand our intense sun.

Use seed trays with a well-draining seed-starting mix. Bottom watering is great for lavender, as it prevents damping-off and encourages strong root growth. Keep the trays warm (around 70°F) and provide plenty of light, especially since spring can be late getting started here.

Transplant your lavender seedlings outdoors in early to mid June, once the risk of frost has passed. Before planting, harden them off for about a week by gradually exposing them to outdoor conditions. This is crucial in our climate, where the sun can be intense even in early summer.

Space the plants 12-18 inches apart to allow for good air circulation. Honestly, buying established starts is the easiest way to guarantee success with lavender in our short season.

Lavender thrives on neglect, especially here in our dry Mountain climate. Overwatering is a death sentence for this plant. Let the soil dry out completely between waterings.

During our moderate-at-altitude summers, water deeply about once every 2-3 weeks, or when the top two inches of soil are dry to the touch. Use the "finger test" – if the soil feels moist two inches down, don't water. Aim for about an inch of water each time. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our cool nights.

Signs of underwatering include wilting or drooping leaves, while yellowing leaves often indicate overwatering. A light layer of gravel mulch around the base of the plant can improve drainage and prevent soil from splashing onto the foliage.

Pruning is essential for maintaining a healthy and productive lavender plant. After flowering, usually in late summer, deadhead the spent blooms. This encourages more blooms and keeps the plant tidy.

Shape the plant into a neat mound by cutting back the stems by about one-third. Be careful not to cut into the old, woody growth, as lavender doesn't typically regrow from there. As our first frosts approach in early September, stop pruning to allow the plant to harden off for winter.

You can expect your first lavender harvest in early to late September. The key is to harvest the flower stems when the buds are showing color but haven't fully opened. This is when the fragrance is most intense.

Cut long stems in the morning, after the dew has dried, using sharp scissors or pruning shears. Gather the stems into small bundles and hang them upside down in a cool, dark, and dry place to dry. This preserves the color and fragrance.

Harvesting encourages continued blooming, so keep cutting those flower stems throughout the season. As the first frost approaches, harvest any remaining buds to dry indoors.

Here are the top 3 problems you might encounter with lavender in our Mountain climate:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and a general decline in plant health. The roots will be brown and mushy.
• What causes it: Overwatering, poorly draining soil, or excessive rainfall. Our alkaline soil can sometimes retain too much moisture.
• How to fix/prevent it: Ensure excellent drainage by planting in raised beds or amending the soil with gravel. Water sparingly, only when the soil is dry to the touch.

Shab Disease

• What it looks like: Brown or black spots on the leaves and stems, often accompanied by a rapid decline in plant health.
• What causes it: A fungal disease that thrives in humid conditions. Even though we have low humidity, cool nights can create pockets of moisture.
• How to fix/prevent it: Provide good air circulation by spacing plants adequately. Remove and destroy any infected plant material.

Phytophthora

• What it looks like: Sudden wilting, especially during warm weather. Dark lesions on the stems near the soil line.
• What causes it: A soilborne pathogen that attacks the roots. Poor drainage and overwatering contribute to the problem.
• How to fix/prevent it: Improve drainage, avoid overwatering, and consider using a fungicide specifically labeled for Phytophthora.

Mountain West Specific Challenges: While our low humidity helps prevent many fungal diseases, our intense sun can stress plants that are not properly hardened off. Be sure to provide adequate drainage and avoid overwatering to keep your lavender healthy and thriving.

Lavender loves company that shares its preferences for sun and well-drained soil. Rosemary, thyme, and sage are excellent companions because they also enjoy full sun and dry conditions, creating a beneficial microclimate. Roses also pair well with lavender, as they appreciate similar growing conditions and the lavender can help deter pests.

Avoid planting mint near lavender. Mint is a water hog and tends to spread aggressively, potentially crowding out the lavender and creating a too-moist environment that lavender hates.