Lavender in Zone 3A — Mountain West

Lavender thrives in our Mountain West gardens, rewarding us with its calming fragrance and beautiful blooms. It's perfect for culinary uses, aromatherapy, or simply adding a touch of elegance to your landscape. The intense sunlight we get here helps concentrate the essential oils, giving you incredibly fragrant lavender.

Growing lavender in Zone 3A can seem daunting with our short, 96-day growing season and alkaline soil. But with careful planning and attention to watering, you can absolutely enjoy this Mediterranean herb. Timing is key, and we'll cover everything you need to know.

Starting lavender from seed indoors is possible, but honestly, it can be a bit finicky. If you're up for a challenge, begin in late March through mid April, giving your seedlings about 10 weeks to develop before transplanting. If you're new to lavender, consider buying starts instead for more reliable results.

Use seed trays with a well-draining seed starting mix. Keep the soil consistently moist (bottom watering is great for this) and provide plenty of light – a grow light is almost essential here given our late spring start. Remember, even though the days are getting longer, our cool spring nights can still slow things down.

Transplant your lavender seedlings outdoors in mid to late June, once the risk 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 temperature swings we often experience.

Space your plants 12-18 inches apart in a location that receives full sun. While we rarely worry about humidity, keep an eye on the forecast. If we are getting a rainy spell, wait a few days. Lavender hates wet feet. Honestly, for best results, buy established starts from a local nursery. It gives you a big head start in our short season.

Watering is where many Mountain gardeners go wrong with lavender. Remember, it's very drought-tolerant and thrives in poor, dry soil. Our moderate-at-altitude summer heat and low humidity mean you'll likely underwater it before you overwater it.

During the first few weeks after transplanting, water thoroughly once a week to help the roots establish. After that, water only when the top 2 inches of soil feel dry to the touch – use the finger test! In a typical Mountain summer with 10-20 inches of rainfall, that might mean watering only every 2-3 weeks, or even less if we get some rain. Aim for about 1 inch of water per week when you do water.

Water at the base of the plant to avoid wetting the foliage. Overhead watering isn't usually a problem given our dry climate, but it's still best to avoid it. Signs of underwatering include wilting leaves and stunted growth. Overwatering, on the other hand, can lead to root rot, which is deadly. The leaves will yellow and the plant will look unhealthy.

A light mulch of gravel or small stones can help improve drainage and reflect sunlight, which lavender loves. Avoid using organic mulches like wood chips, as they can retain too much moisture.

Pruning is essential for keeping your lavender plants healthy and productive. The main goal is to deadhead spent flowers and shape the plant into a nice, rounded mound.

After the flowers fade in late summer, prune the stems back by about one-third, being careful not to cut into the old wood. Lavender doesn't regrow well from old wood, so avoid cutting too far back. This pruning encourages new growth and helps maintain the plant's shape.

As our first frost approaches around early September, stop pruning. Any new growth stimulated by late-season pruning won't have time to harden off before winter, making it vulnerable to frost damage.

You can expect your first lavender harvest around mid-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. This is when the essential oils are at their peak. Cut the stems as long as possible, leaving several 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, well-ventilated place. Once they're completely dry, you can strip the flowers from the stems and use them in various crafts, recipes, or potpourri. Even as our first frost approaches in early September, you can still harvest the last of your lavender.

Even in our relatively problem-free Mountain gardens, lavender can face a few challenges. Here are three common issues to watch out for:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and a general decline in plant health. The roots may appear brown and mushy.
• What causes it: Overwatering or poorly draining soil. Lavender hates wet feet, and our alkaline soil, when combined with too much water, can create the perfect conditions for root rot.
• How to fix/prevent it: Ensure your lavender is planted in well-draining soil. Water sparingly, only when the top 2 inches of soil are dry. If you suspect root rot, carefully dig up the plant and inspect the roots. Remove any affected roots and replant in fresh, well-draining soil.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and brown spots on the stems. The plant may eventually die.
• What causes it: This fungal disease is more common in humid climates, but it can still occur in the Mountain West, especially during periods of prolonged moisture.
• How to fix/prevent it: Improve air circulation around the plants by spacing them adequately. Avoid overhead watering. Remove and destroy any infected plant material.

Phytophthora

• What it looks like: Similar to root rot, with yellowing leaves, wilting, and a general decline in plant health. A dark brown discoloration may appear on the stems near the soil line.
• What causes it: A soilborne pathogen that thrives in wet conditions. Poor drainage and overwatering are major contributors.
• How to fix/prevent it: Ensure excellent drainage. Avoid overwatering. Improve air circulation around the plants. Remove and destroy any infected plants.

Mountain West Specific Challenges: Our moderate-at-altitude summer heat, low humidity, and dry rainfall generally work in lavender's favor. However, even a few weeks of unusually wet weather can create conditions that favor fungal diseases. Pay close attention to watering, ensure good drainage, and provide adequate air circulation to keep your lavender healthy.

Lavender makes a wonderful companion plant for other herbs and flowers in our Mountain gardens.

Rosemary, thyme, and sage all share similar growing requirements as lavender – full sun, well-draining soil, and low water. They also attract beneficial insects that can help control pests. Roses also appreciate lavender nearby, as it can help deter aphids and other rose pests.

Avoid planting lavender near mint. Mint is a vigorous grower that can quickly outcompete lavender for resources. It also prefers moist soil, which is the opposite of what lavender needs.