Lavender in Zone 7B — Pacific Northwest

Lavender is a fantastic addition to any Pacific Northwest garden. The fragrance alone is worth it, and the flavor adds a unique touch to culinary creations. Plus, the bees adore it, and the cool nights here really bring out the best in its aromatic oils.

While we do have our challenges, like late blight concerns and cool soil in spring, Lavender is surprisingly well-suited to our 193-day growing season. With the right timing and techniques, you can enjoy a thriving lavender patch here.

Starting lavender from seed indoors can be a bit tricky, and honestly, most gardeners in the PNW find more success with starts from a local nursery. But if you're up for the challenge, go for it!

If you want to start from seed, aim for mid-February through early March. You'll need seed trays, a heat mat to keep the soil around 70°F, and grow lights since our spring days are often overcast. Bottom watering is your friend here – it helps prevent damping off. Just set the tray in a shallow dish of water until the surface soil is moist.

Transplanting lavender outdoors is best done in late April through mid-May. Before you plant, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space your plants 12-18 inches apart in a sunny spot with well-draining soil. Even in late April, the soil can still be cool here, so be patient and avoid transplanting if there's a late frost in the forecast. Honestly, buying established starts from a reputable nursery will give you a much better head start.

Lavender is very drought-tolerant and prefers dry conditions, which, luckily, our mild summers and dry summer months provide. Overwatering is a surefire way to kill it, so be cautious.

During our wet springs, you likely won't need to water at all unless you're experiencing an unusual dry spell. Once the dry summer months arrive, check the soil moisture about 2 inches down – the "finger test." If it's dry, give your plants a good soaking at the base, aiming for about 1 inch of water per week. Avoid overhead watering as much as possible; the less humidity around the foliage, the better.

If the leaves start to yellow and droop, you're likely overwatering. If they're wilting and the soil is bone dry, you're underwatering. A light layer of gravel mulch around the base of the plants can help improve drainage and prevent soil splash.

Pruning is important for maintaining the shape and health of your lavender plants. The main goal is to deadhead spent flowers and encourage bushier growth.

After the first flush of blooms in late summer, prune back the flower stems, shaping the plant into a nice mound. Aim to cut back by about one-third, but never cut into the old wood (the woody, thicker stems). Lavender doesn't regrow from old wood. As the first frost approaches around late October, give your plants a final light trim to remove any remaining flower stems.

You can expect your first harvest of lavender in late July through early 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. This is when the essential oils are most concentrated. Cut the stems as long as possible, leaving a few inches of foliage on the plant. To encourage continued production, keep harvesting throughout the blooming season.

As the first frost approaches in late October, harvest any remaining flower stems to dry and enjoy throughout the winter. Gather the cut stems into small bundles and hang them upside down in a cool, dark, dry place to dry completely.

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

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and stunted growth. The roots will be brown and mushy.
• What causes it: Overwatering and poor drainage, especially during our wet springs.
• How to fix/prevent it: Plant in well-draining soil, avoid overwatering, and consider raised beds or containers if your soil is heavy clay. Amend the soil with gravel and coarse sand to improve drainage.

Shab Disease

• What it looks like: Brown or black spots on the leaves and stems, often starting at the base of the plant.
• What causes it: A fungal infection favored by humid conditions.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning to open up the center of the plant. Remove and destroy any infected plant material. Avoid overhead watering.

Phytophthora

• What it looks like: Rapid wilting and death of the plant, often starting with the roots and moving upwards.
• What causes it: A soilborne pathogen that thrives in wet conditions.
• How to fix/prevent it: Ensure excellent drainage, avoid overwatering, and consider using disease-resistant lavender varieties. There is no cure for phytophthora once a plant is infected.

Pacific Northwest Specific Challenges: Our mild summers and dry-summer rainfall are generally favorable for lavender, but our wet springs and the potential for late blight can create challenges. Be vigilant about drainage, avoid overwatering, and monitor your plants closely for any signs of disease.

Lavender makes a great companion for other Mediterranean herbs like rosemary, thyme, and sage. These plants all prefer similar growing conditions (full sun and well-drained soil) and can even enhance each other's flavors and fragrances. Roses also benefit from being planted near lavender, as the lavender helps to deter pests like aphids.

Avoid planting lavender near mint, as mint is very invasive and can quickly outcompete lavender for resources. Plus, mint prefers moist soil, which is the opposite of what lavender needs.