Lavender in Zone 7A — Mountain West

Lavender is a fantastic addition to any high-altitude garden. The fragrance is wonderful, and you can use the flowers in everything from cooking to crafts. Plus, those cool nights even in summer concentrate the oils, giving you intensely aromatic blooms.

Our short season and alkaline soil here in the Mountain West can seem daunting, but lavender is surprisingly well-suited to our conditions. With a little planning and attention to timing, you can enjoy beautiful, fragrant lavender in your garden. You have about 173 days, so let's make them count!

Starting lavender from seed indoors is possible, but it can be a bit slow and tricky. If you're up for a challenge, sow seeds indoors from mid February through early March, giving them about 10 weeks to get a head start before our last frost.

Use seed trays with a well-draining seed starting mix. Keep the soil consistently moist (bottom watering helps prevent damping off) and provide plenty of light – a grow light is almost essential here given our often-cloudy spring. Remember, our late spring means patience is key.

Transplant your lavender seedlings outdoors in early to late May, once the danger of frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler temperatures.

Space your lavender plants 12-18 inches apart to allow for good air circulation. Keep in mind that sudden temperature swings are common in the mountains during transplant time, so be ready to cover them if a late frost threatens. Honestly though, unless you're committed, buying established starts from a local nursery is often the most reliable way to get lavender going in our short season.

Lavender thrives on neglect, especially here in the Mountain West. Our low humidity and dry climate mean overwatering is a much bigger threat than underwatering. Let the soil dry out significantly between waterings.

During the growing season, from late May through September, water deeply about every 2-3 weeks, or when the top 2 inches of soil feel dry to the touch – use the finger test! Give them a good soak, aiming for about 1 inch of water per week, but avoid overhead watering, as it can promote fungal diseases in our dry air.

Yellowing leaves are a sign of overwatering, while wilting indicates underwatering. A light mulch of gravel or rock around the base of the plant helps retain moisture without suffocating the roots.

Pruning is essential for maintaining the shape and vigor of your lavender plants. After the first flush of blooms in late summer, deadhead the spent flowers by cutting the stems back to just above the first set of leaves.

This encourages a second, smaller bloom. In the fall, before our first frost arrives around early October, give your lavender plants a more significant pruning, shaping them into a neat mound. Be careful not to cut back into the old wood, as lavender doesn't typically regrow from there.

You can expect your first lavender harvest from early August through mid September, depending on the variety and the weather. The best time to harvest is in the morning, after the dew has dried, when the flower buds are plump and deeply colored but not fully open.

Cut the stems as long as possible, leaving several inches of foliage on the plant. Bundle the stems together with twine and hang them upside down in a cool, dark, and dry place to dry. This preserves the color and fragrance of the flowers.

Harvesting encourages continued blooming, so keep cutting those stems throughout the season. As frost approaches, harvest any remaining flower stems to dry, even if they aren't fully mature. You can still use the buds for sachets or potpourri.

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

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting despite moist soil, mushy brown roots.
• What causes it: Poor drainage and excessive watering, especially in our alkaline soil that doesn't always drain well.
• How to fix/prevent it: Plant lavender in well-draining soil, amend heavy clay soils with gravel, and water sparingly. Ensure good drainage in pots.

Shab Disease

• What it looks like: Stunted growth, distorted leaves, and brown or black lesions on stems.
• What causes it: A fungal disease that thrives in humid conditions. While we have low humidity, prolonged periods of rain can create a favorable environment.
• How to fix/prevent it: Remove and destroy infected plant parts. Ensure good air circulation around plants. Avoid overhead watering.

Phytophthora

• What it looks like: Rapid wilting, browning leaves, and dark lesions at the base of the plant.
• What causes it: A soilborne water mold that attacks the roots, often spread through contaminated soil or water.
• How to fix/prevent it: Improve soil drainage, avoid overwatering, and use disease-free potting mix. Remove and destroy infected plants.

Mountain West Specific Challenges: Our intense sun can actually be a benefit for lavender, promoting strong growth and concentrated oils. However, our dry air and alkaline soil require careful attention to watering and soil drainage to prevent root rot. Hail can also damage plants, so consider protective netting if hail is common in your area.

Lavender makes a great companion plant for many herbs and flowers. Rosemary, thyme, and sage all share similar growing requirements – full sun, well-draining soil, and low water – and can help deter pests. Roses also benefit from being planted near lavender, as the lavender helps repel aphids.

Avoid planting lavender near mint. Mint is aggressive and needs more moisture, which can lead to overwatering the lavender and creating conditions that promote root rot.