Lavender in Zone 4B — Mountain West

Lavender is a fantastic addition to any Mountain West garden. Its fragrant blooms attract pollinators, its flavor enhances culinary dishes, and its calming scent provides aromatherapy benefits. Plus, those cool nights we get even in summer seem to intensify the fragrance. The satisfaction of growing your own lavender, despite our high altitude and intense sun, is well worth the effort.

Our short growing season and alkaline soil present some challenges, but with careful timing and attention to soil drainage, you can absolutely cultivate beautiful lavender. You'll be working within a roughly 128-day window from our last frost around mid-May to our first frost around mid-September, so planning is key.

Starting lavender from seed indoors is possible, but honestly, it can be a slow and sometimes frustrating process. It really only makes sense if you're after a very specific variety that's hard to find as a transplant. If you're up for the challenge, start your seeds indoors from mid-March through early April, about 10 weeks before you plan to transplant.

Use seed trays with a well-draining seed-starting mix. Lavender needs warmth to germinate, so a heat mat is helpful. Once seedlings emerge, provide plenty of light – a grow light is ideal, especially with our late springs. Water from the bottom to avoid damping off.

Transplanting lavender outdoors is best done from late May through early June, after the risk of frost has passed. Because our weather can still be unpredictable at that time of year, keep an eye on the forecast.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Space them 12-18 inches apart to allow for good air circulation. Honestly, for reliable results, I recommend buying established starts from a local nursery. It's just easier and faster than starting from seed.

Lavender thrives on neglect, making it perfect for our dry Mountain West climate. Overwatering is a far bigger problem than underwatering. Once established, lavender is very drought-tolerant and prefers well-drained, even poor, soil.

During the growing season, 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 feels dry, it's time to water. In our climate, with typical highs around 85°F and low humidity, that might mean watering about once a week, or even less. Always water at the base of the plant to avoid getting the foliage wet, which can encourage fungal diseases.

Signs of underwatering include wilting or drooping leaves. Overwatering can manifest as yellowing leaves or, worse, root rot. A light mulch of gravel can help improve drainage and prevent soil from staying too wet.

Pruning is important for maintaining a healthy and productive lavender plant. After flowering, usually in late summer, deadhead the spent blooms. This encourages the plant to produce more flowers and keeps it looking tidy.

You can also 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 doesn't typically regrow from there. As the first frost approaches around mid-September, stop pruning to allow the plant to harden off for winter.

You can expect your first lavender harvest from late August through late September, depending on the variety and the weather. 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 long, leaving several inches of foliage on the plant. Gather the stems into small bundles and hang them upside down in a cool, dark, and dry place to dry. Continue harvesting throughout the blooming season to encourage more flowers.

As our first frost approaches, harvest any remaining buds to dry and enjoy.

Lavender, even in our Mountain gardens, can face a few problems.

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting even when the soil is moist, and a general decline in the plant's health.
• What causes it: Poor drainage and excessive watering. Our alkaline soil can sometimes retain too much moisture if not amended properly.
• How to fix/prevent it: Ensure excellent drainage by planting in raised beds or amending the soil with gravel. Water sparingly, allowing the soil to dry out between waterings.

Shab Disease

• What it looks like: Distorted, stunted growth and grayish-white fungal growth on the stems and leaves.
• What causes it: A fungal disease that thrives in humid conditions. Though our humidity is low, prolonged periods of wet weather can create favorable conditions.
• How to fix/prevent it: Improve air circulation around the plants by spacing them properly and pruning regularly. Remove and destroy any affected plant parts.

Phytophthora

• What it looks like: Sudden wilting and death of the plant, often accompanied by dark lesions on the stems and roots.
• What causes it: A soilborne pathogen that attacks the roots. Poor drainage and contaminated soil can contribute to the problem.
• How to fix/prevent it: Ensure good drainage and avoid overwatering. Use disease-free potting mix and practice crop rotation to prevent the buildup of pathogens in the soil.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity generally benefit lavender, reducing the risk of fungal diseases. However, our dry rainfall means you'll need to monitor soil moisture carefully, especially during prolonged dry spells. Good drainage is still crucial to prevent root rot, even in our arid climate.

Lavender benefits from companion plants that share similar needs – full sun and well-drained soil. Rosemary, thyme, and sage are all excellent companions, as they attract beneficial insects and thrive in similar conditions. Roses also make good companions, as they appreciate the same well-drained soil and full sun.

Avoid planting lavender near mint, as mint's aggressive growth can quickly overwhelm lavender and steal valuable resources. Plus, mint prefers more moisture than lavender, creating an incompatible growing environment.