Lavender in Zone 7A — Pacific Northwest

Lavender is absolutely worth growing here in the PNW. Its fragrance is amazing, and the flavor it adds to both sweet and savory dishes is wonderful. Plus, our cool nights really bring out the best in its aromatic oils. Growing your own lavender and using it in everything from teas to soaps is incredibly satisfying.

We do have our challenges, like cool soil in spring and the occasional bout of late blight affecting nearby plants. However, with a little planning and attention to timing during our 183-day growing season, you can definitely have thriving lavender.

Starting lavender from seed indoors is possible, but it can be slow and a little tricky. Honestly, for most of us in the PNW, buying starts is a more reliable way to go. However, if you're up for the challenge, start your seeds indoors from mid-February through early March, about 10 weeks before you plan to transplant them outside.

Use seed trays with a well-draining seed starting mix. Lavender needs warmth to germinate, so a heat mat underneath the trays can be helpful, especially with our overcast spring days. Make sure they get plenty of light; a grow light is almost essential. Water from the bottom to avoid damping off; set the tray in a shallow dish of water until the top of the soil is moist.

Transplant your lavender outdoors from early to late May, once the soil has warmed up a bit and 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 prevents transplant shock.

Space your lavender plants 12-18 inches apart to give them room to grow into their mature size. While May is usually mild, keep an eye on the forecast for any late cold snaps and be prepared to cover your young plants if needed. Remember, buying starts is often easier than starting from seed!

Lavender thrives on neglect, so overwatering is a much bigger concern than underwatering here in the PNW. During our wet springs, you might not need to water at all, especially if we're getting our typical 36-50 inches of annual rainfall. Once our dry summer months arrive, you'll need to pay closer attention.

A good rule of thumb is to use the "finger test": stick your finger about 2 inches deep into the soil near the base of the plant. If it feels dry, it's time to water. During the driest parts of summer, your lavender might need about an inch of water per week, but only if it hasn't rained. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our climate, even with our dry-summer humidity.

Signs of underwatering include wilting or drooping leaves. Overwatering, on the other hand, can cause yellowing leaves and, eventually, root rot. A light mulch of gravel or pea stone around the base of the plant can help improve drainage and prevent the soil from staying too wet.

Pruning is important for keeping your lavender healthy and productive. The main thing is to deadhead spent flowers throughout the blooming season, which encourages more blooms. Simply snip off the flower stems just below the spent blooms.

After flowering is finished, usually late summer or early fall, give your lavender a more substantial pruning. Shape it into a nice mound by cutting back about one-third of the growth. The most important thing to remember is never to cut into the old, woody growth, as it won't regrow from there. As the first frost approaches around mid-October, stop pruning to allow the plant to harden off for winter.

You can expect your first lavender harvest from early August through 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 aren't fully open yet. This is when the essential oils are most concentrated. 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 the plant to produce more flowers, so keep harvesting throughout the blooming season. As mid-October approaches and the first frost threatens, harvest any remaining flower stems, even if they aren't quite perfect. You can still dry them for use in sachets or potpourri.

Here are three common problems you might encounter with lavender in the PNW:

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. The roots themselves will be brown and mushy.
• What causes it: Overwatering and poorly draining soil create an environment where the roots can't get enough oxygen, leading to fungal growth and rot. Our wet springs can exacerbate this issue.
• How to fix/prevent it: Ensure your lavender is planted in well-draining soil. Amend heavy clay soil with gravel or sand. Water sparingly, only when the top 2 inches of soil are dry. Consider planting in raised beds or containers to improve drainage.

Shab Disease

• What it looks like: Stunted growth, yellowing leaves, and eventual death of the plant. Brown lesions might appear on the stems near the base.
• What causes it: This fungal disease thrives in humid conditions and can be spread through infected soil or plant debris.
• How to fix/prevent it: Remove and destroy any infected plants immediately. Improve air circulation around your lavender plants by spacing them properly and pruning regularly. Avoid overhead watering.

Phytophthora

• What it looks like: Rapid wilting, browning of leaves, and dark lesions on the stems. The roots will be decayed.
• What causes it: This soilborne pathogen is more active in wet conditions and can infect plants through contaminated soil or water.
• How to fix/prevent it: Ensure excellent drainage by planting in well-draining soil or raised beds. Avoid overwatering. Use disease-free planting material. If Phytophthora is a recurring problem in your garden, consider soil solarization or using resistant lavender varieties.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall might seem ideal for lavender, but our wet springs and occasional late blight outbreaks can pose challenges. Pay close attention to drainage, avoid overwatering, and monitor your plants regularly for any signs of disease.

Lavender makes a great companion plant for several herbs and flowers in the PNW. Rosemary, thyme, and sage all share similar growing requirements – full sun and well-drained soil – and their aromatic oils can help deter pests. Roses also benefit from being planted near lavender, as the lavender can help to repel aphids and other rose pests.

Avoid planting mint near lavender. Mint is extremely invasive and can quickly take over a garden bed, crowding out the lavender and competing for resources. Plus, mint prefers moist soil, which is the opposite of what lavender needs to thrive.