Lavender in Zone 4A — Great Plains

Lavender is a fantastic addition to any Great Plains garden. Its fragrant blooms and silvery foliage add beauty, and you can use it for everything from cooking to crafts. Plus, its drought tolerance makes it well-suited to our variable rainfall.

Our region's extreme temperature swings and potential for drought can be intimidating, but don't let that scare you off. With careful timing and a little planning, you can absolutely grow lavender successfully here. Our 138-day growing season is just enough time to get a good harvest.

Starting lavender from seed indoors is possible, but it can be slow and a bit tricky. If you're up for a challenge, go for it. Otherwise, buying established starter plants is often the easier route for Plains gardeners.

If you're starting seeds, sow them indoors in early to late March, about 10 weeks before you plan to transplant. Use seed trays with good drainage, and provide warmth and plenty of light. Bottom watering is a great way to keep the soil consistently moist without overdoing it. Keep in mind that our springs are variable, and you might need to adjust your timing slightly depending on the year.

Transplant your lavender seedlings outdoors in late May through mid June, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to our intense sunshine and wind.

Space your plants 12-18 inches apart to give them room to grow. Be mindful of late spring frosts. Even though they are "past", we can still get some. Buying starts from a local greenhouse avoids all that risk.

Lavender thrives on neglect, which is perfect for our Great Plains climate. Overwatering is a much bigger threat than underwatering. Remember, it's very drought-tolerant and prefers well-drained soil.

During the growing season, water deeply but infrequently. A good rule of thumb is to water only when the top 2 inches of soil feel dry to the touch. Usually, about an inch of water per week is plenty, and often less is needed, especially if we get rain. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our low-to-moderate humidity.

Pay attention to your plants. Yellowing leaves can be a sign of overwatering, while drooping leaves can indicate underwatering. A light layer of rock mulch can help conserve moisture and improve drainage, which is especially helpful in our variable climate.

Pruning lavender is essential for maintaining its shape and encouraging new growth. After flowering, deadhead the spent blooms and prune back the stems by about one-third, shaping the plant into a nice mound.

Be careful not to cut into the old wood, as lavender doesn't typically regrow from there. In late September, as our first frosts approach, give your plants a final light pruning to remove any remaining flower stalks and tidy up their appearance.

You can expect your first lavender harvest in late August through early October, about 90 days after transplanting. The best time to harvest is in the morning, when the buds are colored but not fully open. This is when the essential oils are most concentrated.

Cut long stems, leaving several inches of growth on the plant. To encourage continued production, harvest regularly throughout the blooming season. As our first frost approaches in late September, harvest any remaining flowers to dry and enjoy indoors. Hang the cut stems upside down in small bundles in a cool, dry place until they're completely dry.

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

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting, and stunted growth. The roots may appear brown and mushy.
• What causes it: Poor drainage and excessive watering. Our variable rainfall, combined with heavy soils, can create soggy conditions.
• How to fix/prevent it: Ensure excellent drainage by planting in well-draining soil or raised beds. Water sparingly, allowing the soil to dry out between waterings. Amend heavy clay soils with compost and gravel to improve drainage.

Shab Disease

• What it looks like: Black or brown spots on the leaves and stems, often followed by wilting and dieback.
• What causes it: A fungal disease favored by humid conditions. While our humidity is generally low-to-moderate, prolonged periods of dampness can create favorable conditions.
• How to fix/prevent it: Provide good air circulation by spacing plants adequately. Avoid overhead watering. Remove and destroy infected plant parts promptly.

Phytophthora Root Rot

• What it looks like: Similar to root rot from overwatering, with yellowing leaves, wilting, and root decay.
• What causes it: A soilborne pathogen that thrives in wet conditions. Poor drainage and overwatering contribute to its spread.
• How to fix/prevent it: Improve soil drainage and avoid overwatering. Use disease-free plants and consider using a fungicide as a preventative measure.

Great Plains Specific Challenges: Our hot summers and variable rainfall can stress lavender plants, making them more susceptible to disease. Ensure proper drainage and avoid overwatering to keep your lavender healthy and thriving. Wind protection is also essential.

Lavender makes a great companion plant for several herbs and flowers in the Great Plains garden. Rosemary, thyme, and sage all share similar growing requirements (full sun, well-drained soil) and can help deter pests. Roses also benefit from being planted near lavender, as lavender can help repel aphids and other rose pests. Avoid planting mint near lavender, as mint is aggressive and can quickly take over, crowding out your lavender plants.