Lavender in Zone 4A — Mountain West

Lavender is absolutely worth the effort in our Mountain gardens. Its fragrance is unmatched, and it thrives in our intense sun, producing beautiful blooms you can use in everything from teas to crafts. Plus, the cool nights we get even in summer help concentrate the oils, giving you intensely aromatic lavender.

Sure, high altitude gardening comes with its challenges. Our short season (around 118 days) means we have to be strategic. But with careful timing, you can absolutely enjoy fragrant lavender in your Zone 4A garden.

Starting lavender from seed indoors is possible, but honestly, it can be a slow and somewhat frustrating process. It's worth considering if you're looking for a specific variety or just enjoy the challenge. For most of us high altitude gardeners, buying starts is the way to go.

If you decide to start indoors, aim for mid-March through early April, about 10 weeks before you plan to transplant. Use seed trays with a well-draining seed starting mix. Provide warmth (a heat mat helps) and plenty of light – a grow light is essential, especially with our late springs where sunlight can still be limited. Bottom watering helps prevent damping off, which can be a problem with seedlings.

Transplant your lavender outdoors in early June, after the risk of frost has passed. Before planting, 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 nights.

Space your lavender plants 12-18 inches apart to allow for good air circulation. Lavender prefers well-drained, even somewhat poor soil, so don't amend the planting hole too much. Honestly, getting reliable results with Lavender from seed is tough, so consider buying starts from a local nursery.

Lavender is a champ when it comes to drought tolerance, which is perfect for our dry Mountain climate. Overwatering is a far bigger threat than underwatering in our region. Remember, we have low humidity and typically only 10-20 inches of rainfall per year.

During the first 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's dry, it's time to water. Aim for about ½ inch of water per week, depending on rainfall. Water at the base of the plant rather than overhead to prevent fungal diseases.

Established lavender plants need very little supplemental watering. You might only need to water them during extended dry spells. Signs of underwatering include wilting or drooping leaves, while yellowing leaves and mushy stems indicate overwatering. A light mulch of gravel or small stones can help improve drainage and prevent soil from staying too wet, which is beneficial in our climate.

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.

Prune your lavender after it finishes flowering, usually in late summer. Cut back the stems by about one-third, but be careful not to cut into the old wood, as it won't regrow. At the end of the season, before our first frost hits around mid-September, give your plants a light tidy-up, removing any dead or damaged growth.

You can expect your first lavender harvest in early to late September, about 90 days from transplanting. The best time to harvest is in the morning, after the dew has dried but before the sun gets too intense.

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 several inches of foliage on the plant. To dry your lavender, tie the stems into small bundles and hang them upside down in a cool, dark, and well-ventilated place. Harvesting encourages continued blooming, so keep an eye on your plants and harvest regularly throughout the season. As the first frost approaches in mid-September, harvest any remaining flower stems to enjoy indoors.

Here are a few common problems you might encounter with lavender in our Mountain gardens:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and mushy stems, especially near the base of the plant.
• What causes it: Overwatering, poor drainage, and heavy soils. Our low humidity can trick you into thinking plants need more water than they do.
• How to fix/prevent it: Ensure excellent drainage by planting in well-draining soil and avoiding overwatering. Water deeply but infrequently. Consider raised beds or amending heavy clay soils with gravel.

Shab Disease

• What it looks like: Gray or brown spots on leaves and stems, followed by wilting and dieback.
• What causes it: A fungal disease that thrives in humid conditions. While we have low humidity, poor air circulation can create localized humid pockets.
• How to fix/prevent it: Provide good air circulation by spacing plants properly and pruning to open up the center of the plant. Remove and destroy any infected plant material.

Phytophthora

• What it looks like: Sudden wilting and death of plants, often starting with the roots.
• What causes it: A soilborne pathogen that thrives in wet conditions. Poor drainage and overwatering are major contributing factors.
• How to fix/prevent it: Improve soil drainage, avoid overwatering, and consider using disease-resistant varieties. Remove and destroy infected plants and soil.

Mountain West Specific Challenges: Our moderate-at-altitude heat and low humidity are generally favorable for lavender, but our alkaline soil can be a problem. Amend the soil with compost to improve drainage and lower the pH slightly. The intense UV light can also stress plants, so provide some afternoon shade if needed, especially for young plants.

Lavender makes a great companion for several plants in our Mountain gardens. Rosemary, thyme, and sage all share similar growing requirements – full sun, well-drained soil, and low water – and their aromatic foliage can help deter pests. Roses also benefit from being planted near lavender, as it can help protect them from aphids.

Avoid planting lavender near mint. Mint requires more moisture and can quickly spread and crowd out lavender, which prefers drier conditions and doesn't like competition.