Winterizing lavender plants that are grown indoors (meaning they are typically in containers and moved inside for the cold season) involves creating an environment that mimics their natural dormancy, while addressing the challenges of an indoor setting. The goal is to keep them alive and healthy through winter so they can thrive again next spring.
Here's how to winterize lavender plants indoors:
1. Prepare for the Move Indoors (Late Fall/Before First Hard Frost)
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Clean and Inspect: Before bringing your lavender indoors, thoroughly inspect the plant for any pests (like aphids, spider mites, or whiteflies) or diseases. Treat any infestations or issues before bringing the plant inside, as pests can quickly spread to other houseplants. Remove any dead or yellowing leaves.
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Prune Lightly (Optional): If your lavender is still quite large or leggy after its main fall prune (if you did one), you can give it a light trim to reduce its size and remove any straggly growth. This makes it easier to manage indoors and encourages a bushier habit. However, avoid a heavy prune right before bringing it in, as new tender growth can be stressed.
2. Choose the Right Indoor Location
The biggest challenges for lavender indoors are usually lack of sufficient light and too much heat.
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Light: Lavender needs a lot of light, even during dormancy. Place your potted lavender in the coolest, brightest spot available.
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An unheated sunroom, cool greenhouse, or a south-facing window that gets at least 4-6 hours of direct sunlight is ideal.
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If natural light is insufficient, consider using supplemental grow lights. Position them a few inches above the plant and leave them on for 10-12 hours a day.
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Temperature: Lavender prefers cool temperatures during its dormant period, ideally between 40-60°F (4-15°C).
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Avoid placing lavender near heat vents, radiators, or fireplaces, as warm, dry air can stress the plant and make it susceptible to pests.
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A cool basement window or an unused guest room can sometimes be suitable if enough light is provided.
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3. Adjust Watering
This is perhaps the most critical factor for indoor lavender survival. Overwatering is a common killer.
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Reduce Frequency Drastically: As the plant is dormant or semi-dormant, its water needs are significantly lower.
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Allow Soil to Dry Out: Water sparingly. Wait until the top 1-2 inches of soil are completely dry before watering again. For larger pots, you might even wait until the top half of the soil feels dry.
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Check Weight: Lift the pot. If it feels surprisingly light, it's probably time to water.
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Proper Drainage: Ensure your pot has excellent drainage holes and that you empty any saucers to prevent the pot from sitting in standing water.
4. Manage Humidity and Air Circulation
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Humidity: Indoor heated environments tend to be very dry. While lavender generally prefers dry air, extreme dryness can still be stressful. You can place the pot on a humidity tray (a shallow tray filled with pebbles and water, ensuring the pot sits on the pebbles, not in the water) to slightly increase local humidity.
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Air Circulation: Good air circulation is vital indoors to prevent fungal issues like powdery mildew, especially if humidity is slightly higher. Ensure the plant isn't crammed in a corner and has room to breathe. An oscillating fan on a low setting for a few hours a day can also help.
5. Fertilizing
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None in Winter: Do not fertilize your indoor lavender during the winter months. This can encourage weak, leggy growth that won't survive well. Resume light fertilization only when you transition it back outside in spring and it begins active growth.
6. Spring Transition Back Outdoors
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Acclimatize Slowly: Once the danger of the last frost has passed in spring and outdoor temperatures are consistently above 40°F (4°C), gradually reintroduce your lavender to outdoor conditions.
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Start by placing the pot in a sheltered, shaded spot for a few hours a day, gradually increasing its exposure to light and wind over 1-2 weeks. This process is called "hardening off" and prevents shock.
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After hardening off, you can move your lavender back to its sunny outdoor spot for the growing season.
By providing a cool, bright environment with very careful watering, you can successfully winterize your lavender indoors and enjoy its fragrance and blooms for many years.