Lavender in Zone 5A — Midwest

Lavender is a fantastic addition to any Midwest garden. Its fragrance is heavenly, the flavor is unique in baking and drinks, and the beautiful purple flowers add a touch of elegance to your landscape. Plus, attracting pollinators is easy with this plant.

Our Midwest weather, with its cold winters and sometimes unpredictable springs, can seem daunting for some plants. But with careful timing and the right approach, you can absolutely grow beautiful lavender here in our Zone 5A gardens. Our 157-day growing season gives you a good window to enjoy this beauty.

Starting lavender from seed indoors is possible, but it can be a bit tricky, even for experienced gardeners. It's generally easier and faster to buy established starter plants from a reputable nursery. But if you're up for the challenge, go for it!

If you want to start seeds indoors, aim for late February through mid March, about ten weeks before you plan to transplant outdoors. Use seed trays with a good seed-starting mix, provide warmth (a heat mat helps), and make sure they get plenty of light. Bottom watering is great to keep the soil consistently moist without disturbing the tiny seeds. Remember, spring in the Midwest can be late getting started, so be patient.

Wait until mid May through early June to transplant your lavender outdoors. This is after the danger of frost has passed. Before planting, 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. Keep an eye on the weather forecast, as we can sometimes get unexpected late frosts even in May. As mentioned before, buying starter plants is usually a more reliable way to get a good lavender crop.

Lavender is very drought-tolerant, which is great for our sometimes-erratic Midwest rainfall. The biggest mistake you can make is overwatering it, especially with our moderate-to-humid summers. Root rot is a real concern.

During the first few weeks after transplanting, water regularly to help the plants establish. Once established, water only when the top 2 inches of soil feel dry to the touch – do the "finger test" to be sure. In general, aim for about 1 inch of water per week, including rainfall. It's best to water at the base of the plant rather than overhead, as this helps prevent fungal diseases in our humid climate.

Watch for signs of underwatering, such as wilting or yellowing leaves. Overwatering signs include mushy stems and leaves. A light mulch of gravel or small stones around the base of the plant can help improve drainage and keep the soil dry, which is especially helpful with our clay soil.

Pruning is essential for keeping your lavender plants healthy and productive. The key is to deadhead after flowering. This means removing the spent flower heads to encourage new growth.

After the main bloom in late summer, prune the plant back by about one-third, shaping it into a nice, rounded mound. Be careful not to cut into the old wood, as lavender doesn't typically regrow from there. As the first frost approaches in early October, stop pruning to allow the plant to harden off for winter.

You can expect your first harvest of lavender in mid August through late September, about 90 days after transplanting. The best time to harvest is when the flower buds are showing good color but haven't fully opened yet. This is when the fragrance is most intense.

Cut the stems long in the morning, after the dew has dried. Gather them into small bundles and hang them upside down in a cool, dark, dry place to dry. Regular harvesting encourages the plant to produce more flowers, so keep cutting those stems! Even as the first frost approaches in early October, you can still harvest any remaining flowers for drying.

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

Root Rot from Overwatering

• What it looks like: Wilting, yellowing leaves, and mushy stems, even when the soil is moist.
• What causes it: Overwatering, poor drainage, and our heavy clay soil can all contribute.
• How to fix/prevent it: Plant in well-draining soil, avoid overwatering, and amend clay soil with compost or other organic matter. Consider raised beds for better drainage.

Shab Disease

• What it looks like: Brown or black spots on the leaves and stems, often accompanied by a general decline in the plant's health.
• What causes it: A fungal disease that thrives in humid conditions and poorly ventilated areas.
• How to fix/prevent it: Ensure good air circulation around the plants, avoid overhead watering, and remove any infected foliage promptly.

Phytophthora

• What it looks like: Rapid wilting, discoloration of the lower stem, and root decay.
• What causes it: A soilborne pathogen that thrives in wet conditions, especially in heavy clay soils.
• How to fix/prevent it: Improve soil drainage, avoid overwatering, and consider using disease-resistant varieties.

Midwest Specific Challenges: Our moderate-to-hot summers, moderate-to-humid humidity, and wet-summer rainfall can create a perfect storm for fungal diseases and root rot in lavender. Be vigilant about watering practices and ensure good air circulation to keep your plants healthy.

Lavender thrives alongside plants that enjoy similar conditions: full sun and well-drained soil. Rosemary, thyme, and sage are excellent companions, as they share those needs. Roses also make good companions, as the lavender can help deter pests that bother roses.

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