Winterizing lavender plants grown outdoors is essential to help them survive cold temperatures, harsh winds, and excessive moisture. The specific steps you take will depend on your climate's winter severity and the hardiness of your lavender variety. English lavenders (Lavandula angustifolia) are generally the most cold-hardy, while French (Lavandula dentata) and Spanish (Lavandula stoechas) lavenders are more tender.
Here's a guide to winterizing outdoor lavender plants:
1. Ensure Excellent Drainage (Year-Round & Crucial for Winter)
Lavender absolutely despises "wet feet," especially in cold, dormant months. Soggy roots can quickly lead to rot when the soil is cold or freezes.
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During Planting: If your soil is heavy clay, ensure you amended it significantly with grit, coarse sand, or small gravel to improve drainage. Planting on a slight mound or in a raised bed can also help.
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Ongoing: Ensure that water doesn't pool around the base of the plant. Clear away any debris that might impede drainage.
2. Adjust Watering in Fall
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As temperatures drop in late fall, significantly reduce your watering frequency. Lavender naturally needs less water as it enters dormancy.
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The goal is to keep the soil on the drier side. Avoid overwatering, as this is a common cause of winter damage. Natural rainfall is often sufficient.
3. Pruning for Winter Survival
The timing of your last prune before winter is critical.
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In Colder Climates (USDA Zones 5-7, or areas with harsh winters):
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DO NOT perform a heavy prune in late fall or early winter. A heavy prune encourages new, tender growth that will not have time to harden off before freezing temperatures arrive. This new growth is highly susceptible to frost damage and can weaken or kill the plant.
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Instead, perform your main pruning in early spring, after the last hard frost has passed and you see definite signs of new green growth emerging. At that point, you'll prune back about one-third of the plant and remove any stems that clearly died back over winter.
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You can do a very light "deadheading" (removing only spent flower stalks) in late summer, but avoid deep cuts.
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In Milder Climates (USDA Zones 8 and warmer):
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You can perform your main prune in late summer to early fall (typically by mid-September) after the main bloom has faded. This helps maintain the plant's shape and encourages bushiness for the following year.
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Even in milder climates, try to avoid pruning too late in fall if there's a chance of sudden or unexpected cold snaps.
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4. Mulching for Root Protection
Mulch helps insulate the soil and roots from extreme temperature fluctuations (freeze-thaw cycles) and and can provide some protection against deep freezes.
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When to Apply: Apply mulch in late fall, after the ground has started to cool or even lightly freeze. Applying it too early can trap warmth and prevent the plant from going fully dormant.
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Type of Mulch: Use a coarse, well-draining organic mulch. Good options include:
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Straw
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Pine needles
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Small gravel or pea gravel
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Coarse sand
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Application: Apply a 2-3 inch layer of mulch around the base of the plant.
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Crucial Caution: Keep the mulch 2-3 inches away from the crown (base) of the plant. Piling mulch directly against the stem can trap moisture, lead to rot, and attract pests, which is detrimental to lavender's health. Avoid heavy, moisture-retaining mulches like shredded bark or compost right up against the crown.
5. Wind Protection (Optional, for Exposed Areas)
Harsh, dry winter winds can dehydrate and damage lavender foliage, especially for more tender varieties or young plants.
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Burlap Screens: If your lavender is in a very exposed, windy location, you can erect a temporary burlap screen or windbreak on the windward side of the plant. Stake the burlap into the ground around the plant, ensuring there's still good air circulation.
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Evergreen Boughs: In some colder regions, evergreen boughs (from discarded Christmas trees, for example) can be laid over the plant for light insulation and wind protection.
6. Snow Cover (Natural Insulation)
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If your region receives consistent snow, consider it a natural protector. A blanket of snow acts as an excellent insulator, protecting the plant from extreme cold and drying winds.
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If heavy, wet snow accumulates, gently brush some of it off the plant to prevent branches from breaking under the weight.
7. Variety Selection (Long-Term Strategy)
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If you're in a colder climate (Zone 5-7), choosing a cold-hardy English lavender variety like 'Munstead' or 'Hidcote' at planting time significantly increases its chances of surviving winter outdoors without extensive protection. Lavandins (Lavandula x intermedia) like 'Grosso' or 'Provence' are also quite hardy. French and Spanish lavenders are generally less cold-tolerant and might struggle outdoors in zones colder than 8.
By implementing these strategies, you can give your outdoor lavender the best chance to successfully overwinter and return vibrant and fragrant in the spring.