Lavender in Zone 6B — Mountain West

Lavender thrives in our Mountain West gardens, offering fragrant blooms, culinary uses, and a calming presence. Its ability to handle our intense sun and alkaline soil makes it a natural fit, and those cool nights even in summer help concentrate its oils, boosting its scent and flavor.

Our short growing season and occasional hail can present challenges, but with careful timing and a few protective measures, you can absolutely enjoy a thriving lavender patch. The 163-day growing season means starting early is key to enjoying those fragrant blooms.

Starting lavender from seed indoors is possible, but it can be slow and a bit finicky. If you're up for the challenge, begin in late February through mid March, giving you about 10 weeks to get them ready for transplanting.

Use seed trays with a well-draining seed starting mix. Bottom watering is ideal to prevent damping off. Provide plenty of light and warmth, mimicking the intense sun they crave. Remember, our spring weather here in the mountains can be unpredictable, so starting indoors gives you a head start.

Transplant your lavender seedlings outdoors in early to late May, after the danger of frost has passed. Harden them off for about a week beforehand, gradually exposing them to the elements.

Space plants 12-18 inches apart to allow for good air circulation. While starting from seed is possible, purchasing established starts from a local nursery is often a more reliable way to ensure success in our short season. Be prepared for unexpected temperature swings that are common during this time of year.

Lavender is very drought-tolerant and thrives in the dry conditions of the Mountain West. Overwatering is a far bigger threat than underwatering. Our low humidity and limited rainfall actually benefit lavender, reducing the risk of fungal diseases.

During the growing season, water deeply but infrequently, allowing the soil to dry out completely between waterings. A good rule of thumb is the "finger test": stick your finger about 2 inches into the soil. If it's dry, it's time to water. Typically, in our climate, established lavender needs only about 1 inch of water per week, if that. Water at the base of the plant to avoid wetting the foliage.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can lead to yellowing leaves and root rot. A light mulch of gravel can help improve drainage and keep the soil surface dry.

Pruning is essential for maintaining the shape and vigor of your lavender plants. After flowering, typically from early August through mid September, deadhead the spent blooms.

Shape the plant into a nice mound by cutting back the stems by about one-third. Be careful not to cut into the old wood, as lavender rarely regrows from these areas. As the first frost approaches in early October, avoid any heavy pruning.

Your first lavender harvest will likely be in early August through mid September, about 90 days after transplanting. The best time to harvest is in the morning, after the dew has dried.

Look for flower stems where the buds are showing color but not fully open. Cut the stems as long as possible without damaging the plant. To dry, tie the stems into small bundles and hang them upside down in a cool, dark, and well-ventilated place.

Regular harvesting encourages continuous bloom throughout the season. As the first frost approaches in early October, harvest any remaining flower stems to dry for later use.

Here are three common problems you might encounter with lavender in the Mountain West:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and a general decline in plant health. Roots may appear brown and mushy.
• What causes it: Excessive moisture in the soil, often due to overwatering or poor drainage. Our alkaline soil is typically well-draining, but amending too heavily with compost can retain too much moisture.
• How to fix/prevent it: Ensure excellent drainage by planting in raised beds or amending the soil with gravel. Water deeply but infrequently, allowing the soil to dry out between waterings.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and eventual death of the plant. Black spots may appear on the stems.
• What causes it: A fungal disease that thrives in humid conditions. While our humidity is low, prolonged periods of wet weather can create favorable conditions.
• How to fix/prevent it: Improve air circulation by spacing plants adequately. Avoid overhead watering. Remove and destroy any infected plants.

Phytophthora

• What it looks like: Rapid wilting, leaf discoloration, and eventual death of the plant. The base of the stem may appear dark and water-soaked.
• What causes it: A soilborne pathogen that attacks the roots. Poor drainage and overwatering can exacerbate the problem.
• How to fix/prevent it: Ensure excellent drainage. Avoid planting lavender in areas with a history of Phytophthora. Use disease-free planting material.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally favor lavender, reducing the risk of many fungal diseases. However, it's essential to avoid overwatering, even during dry spells. The intense UV radiation can also stress plants if they are not properly acclimated.

Good companions for lavender include rosemary, thyme, and sage. These Mediterranean herbs share similar growing requirements: full sun, well-drained soil, and low water needs. Roses also make excellent companions, as they attract pollinators that will benefit your lavender.

Avoid planting mint near lavender. Mint is invasive and can quickly overcrowd lavender, competing for resources. Mint also prefers moist soil, which is the opposite of what lavender needs.