Lavender in Zone 5A — Mountain West

Lavender is a rewarding addition to any Mountain West garden. Its fragrant blooms thrive in our intense sun, and the cool nights even in summer seem to intensify its flavor. Plus, it’s incredibly versatile – use it in cooking, crafts, or simply enjoy its calming scent in your garden.

Growing Lavender in our Zone 5A climate has its challenges, mainly our short season and alkaline soil. But with careful timing and attention to drainage, you can successfully grow this Mediterranean herb. Our 138-day growing season means starting indoors is the best bet for success.

Starting Lavender from seed indoors is possible, but it can be slow and tricky. You'll want to get those seeds going in early to late March, about 10 weeks before you plan to transplant them outdoors. This gives them a head start to make the most of our short growing season.

Use seed trays with a well-draining seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water until the surface of the soil is damp. Provide warmth and plenty of light, either from a sunny south-facing window or, even better, a grow light. Remember that spring in the Mountain West can be late, so don't rush the process.

Transplant your Lavender seedlings outdoors in late May through mid June, once the risk of frost has passed. Before transplanting, 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 temperatures.

Plant them 12-18 inches apart in a sunny spot with well-draining soil. At transplant time, we can still get some unexpected cold snaps or even hail, so be prepared to cover your young plants if needed. Honestly, for reliable results, buying starts from a local nursery is often the easiest way to go.

Lavender is very drought-tolerant and thrives in poor, dry soil, which makes it a great fit for our dry Mountain West climate. Overwatering and humidity are its main enemies. Excellent drainage is crucial to prevent root rot.

During the first few weeks after transplanting, water regularly to help the plants establish. After that, water deeply but infrequently. Let the soil dry out almost completely between waterings. Stick your finger about 2 inches deep into the soil – if it's dry, it's time to water. Typically, established Lavender needs only about 1 inch of water per week, if that, especially if we get any rain. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our cool evenings.

Signs of underwatering include wilting or yellowing leaves. Overwatering can cause the leaves to turn brown or black, and the plant may develop root rot. Mulching with gravel or small stones can help improve drainage and prevent the soil from staying too wet.

Pruning is essential to keep your Lavender plants healthy and productive. The goal is to encourage new growth and maintain a compact, bushy shape.

After flowering, deadhead the spent blooms. Then, prune the plant back by about one-third, shaping it into a mound. Be careful not to cut into the old wood, as Lavender doesn't regrow from there. As the first frost approaches in late September, stop pruning to allow the plant to harden off for the winter.

You can expect your first Lavender harvest in late August through early October, about 90 days from transplanting. The best time to harvest is when the flower buds are colored but not fully open. This is when the essential oils are most concentrated.

Cut the long stems in the morning, after the dew has dried. Gather the stems into small bundles and tie them with twine. Hang the bundles upside down in a cool, dark, and dry place to dry. Regular harvesting encourages the plant to produce more blooms throughout the season.

As our first frost approaches in late September, harvest any remaining flowers to dry or use fresh.

Here are the top 3 problems you might encounter with Lavender in the Mountain West:

Root Rot from Overwatering

• What it looks like: Yellowing or wilting leaves, stunted growth, and a foul odor coming from the soil.
• What causes it: Soggy soil that deprives the roots of oxygen. Common in our region if we get unexpected summer rains.
• How to fix/prevent it: Ensure excellent drainage by planting in well-draining soil. Water deeply but infrequently, allowing the soil to dry out between waterings. Avoid overwatering, especially during periods of rain.

Shab Disease

• What it looks like: Brown or black spots on the leaves and stems.
• What causes it: A fungal disease that thrives in humid conditions. Although our humidity is low, cool nights can create enough moisture for this disease to develop.
• How to fix/prevent it: Provide good air circulation around the plants. Remove and destroy any infected plant parts. Avoid overhead watering.

Phytophthora

• What it looks like: Rapid wilting and death of the plant, often starting with the roots.
• What causes it: A soilborne pathogen that attacks the roots. Poor drainage and overwatering can create favorable conditions for this disease.
• How to fix/prevent it: Improve drainage and avoid overwatering. Use disease-free plants. Solarize soil before planting. Remove and destroy infected plants.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry climate are generally favorable for Lavender. However, our alkaline soil can sometimes be a problem. Amend the soil with compost or sulfur to lower the pH if necessary.

Lavender thrives alongside plants that share its love for sunshine and well-drained soil. Rosemary, thyme, and sage are excellent companions, as they all enjoy similar growing conditions and attract beneficial pollinators. Roses also make good companions, as they appreciate the same sunny spot and well-drained soil.

Avoid planting Lavender near mint. Mint prefers moist soil and can quickly spread and overtake the Lavender, competing for resources.