Lavender in Zone 5B — Mountain West

Lavender is a fantastic addition to any Mountain garden. Its fragrance is heavenly, it attracts pollinators like crazy, and it's incredibly versatile in everything from cooking to crafts. Plus, the intense sun and cool nights we get here in Zone 5B actually intensify the oils, giving you even more potent flavor and scent.

Growing Lavender in our high altitude climate does come with challenges. The short season and alkaline soil can be tricky, but with proper timing and a little soil prep, you can definitely succeed. Our 149-day growing season is just long enough to enjoy a bountiful harvest.

Starting Lavender from seed indoors is possible, but honestly, it can be slow and a little fussy. If you're up for a challenge, go for it! Start your seeds indoors from early to late March, giving them about 10 weeks to get a head start before transplanting.

Use seed trays with a well-draining seed starting mix. Keep them consistently warm (around 70°F) and provide plenty of light – a grow light is ideal. Bottom watering is your friend here; it helps prevent damping off. Remember, our spring weather can be unpredictable, so be prepared to keep them indoors a little longer if needed.

Transplanting Lavender outdoors should happen mid May through early June, once the risk of frost has passed. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This will help them adjust to the intense sun and cooler nights.

Space your Lavender plants 12-18 inches apart to allow for good air circulation. Honestly, for reliable results, especially in our short season, consider buying starts from a local nursery. They'll be more established and ready to thrive.

Lavender is a champion in our dry Mountain climate, but that doesn't mean you can neglect it entirely. The key is to avoid overwatering, which is a surefire way to kill it. Remember, it's VERY drought-tolerant.

During the active growing season (roughly June through August), give your Lavender a deep watering about once every 2-3 weeks, or when the top 2 inches of soil feel dry to the touch. We get very little rain, so you'll likely need to supplement. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our cool nights.

In the fall, as temperatures cool down, reduce watering even further. During winter dormancy, you probably won't need to water at all unless we have an unusually dry spell. Signs of underwatering include wilting and drooping leaves, while overwatering can lead to yellowing leaves and root rot. A light mulch of gravel or rock around the base of the plant can help improve drainage and prevent soil from splashing onto the foliage.

Pruning your Lavender is essential for maintaining its shape and encouraging more blooms. After the flowers fade, which is usually in late summer, deadhead the spent blooms by cutting the stems back to just above a leaf node. This encourages a second flush of flowers and keeps the plant looking tidy.

You can also give the plant a light shaping at this time, pruning it into a neat mound. Be careful not to cut back into old wood, as Lavender doesn't typically regrow from there. As the first frost approaches in early October, stop pruning and 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 hot. Look for flower stems where the buds are showing good color but haven't fully opened yet.

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 well-ventilated place. Regular harvesting will encourage the plant to produce more flowers throughout the season. If you have a lot of buds as frost approaches, cut them all – they will dry just fine.

Here are three common problems you might encounter with Lavender in our Mountain gardens:

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 humidity around the base of the plant. Our alkaline soil is a factor, too, as it can retain moisture.
• How to fix/prevent it: Ensure your Lavender is planted in well-draining soil. Water sparingly, allowing the soil to dry out between waterings. Improve drainage by amending the soil with gravel or sand.

Shab Disease

• What it looks like: Brown or black spots on the leaves and stems. The plant may appear stunted and unhealthy.
• What causes it: A fungal disease that thrives in humid conditions. It's less common in our dry climate, but can occur during periods of extended rainfall.
• How to fix/prevent it: Improve air circulation around the plant by spacing it properly. Remove and destroy any infected plant material. Avoid overhead watering.

Phytophthora

• What it looks like: Sudden wilting, yellowing leaves, and dark lesions on the stems. The plant may collapse and die quickly.
• What causes it: A soilborne pathogen that attacks the roots. It's more common in poorly drained soils.
• How to fix/prevent it: Ensure your Lavender is planted in well-draining soil. Avoid overwatering. Consider using a fungicide if the problem persists.

Mountain West Specific Challenges: Our low humidity is a huge advantage when it comes to Lavender, but be careful not to overwater, especially in our dense alkaline soil. The intense sun can also stress the plants if they are not properly established, so provide some afternoon shade during the hottest part of the summer.

Lavender makes a great companion plant for several herbs and flowers in our Mountain gardens. Rosemary, thyme, and sage all thrive in similar conditions – full sun, well-draining soil, and low water – and they can even enhance each other's flavors and scents. Roses also benefit from being planted near Lavender, as it helps to deter pests like aphids.

Avoid planting mint near Lavender, as it has very different water requirements and can quickly take over the garden, crowding out your Lavender plants. Mint likes moisture, and Lavender does not.