How do you winterize lavender plants?

Winterizing lavender plants is essential to ensure their survival and health through the colder months, especially in regions with freezing temperatures. The method you choose depends heavily on your local climate and whether the lavender is planted in the ground or in containers.

Here's a comprehensive guide on how to winterize lavender plants:

1. General Principles for All Lavender

• Reduce Watering: As winter approaches and temperatures drop, lavender enters a dormant or semi-dormant state. Its water needs decrease significantly. Overwatering in winter is a common killer, as soggy roots can lead to rot, especially if the soil freezes. Allow the soil to dry out considerably between waterings.

• Avoid Fertilizing: Do not fertilize lavender in the fall or winter. This can stimulate new, tender growth that is highly susceptible to frost damage. Resume fertilizing only in spring when active growth begins.

• Ensure Excellent Drainage: Lavender absolutely despises wet feet, especially in cold weather. Ensure your soil (in-ground or in pots) drains exceptionally well. If your soil is heavy clay, amending it with grit or sand during planting is crucial.

2. Winterizing In-Ground Lavender

How much protection in-ground lavender needs depends on how cold your winters get and the hardiness of your lavender variety. English lavenders (Lavandula angustifolia, e.g., 'Munstead', 'Hidcote') are generally the most cold-hardy (down to Zone 5), while French (Lavandula dentata) and Spanish (Lavandula stoechas) lavenders are more tender (hardy to Zone 8 or warmer).

• Pruning (Crucial Timing!):

  • In Colder Climates (Zones 5-7): DO NOT perform a heavy prune in the fall. Heavy fall pruning stimulates new growth that will not harden off before winter, leading to severe frost damage or even plant death. Instead, wait until early spring (after the last hard frost and when new green growth appears) to do your main prune, cutting back about one-third of the plant and removing any winter-killed stems. A very light tidy-up to remove spent flowers can be done in late summer, but avoid deep cuts.

  • In Milder Climates (Zones 8+): You can perform your main prune in late summer to early fall (after the main bloom has faded, usually by mid-September). This helps maintain shape and promotes bushiness for the following year. Avoid pruning too late in fall if there's a chance of sudden cold snaps.

• Mulching (for colder climates or new plants):

  • Apply a 2-3 inch layer of coarse, well-draining organic mulch around the base of the plant in late fall, after the ground has started to cool or lightly freeze. Good options include straw, pine needles, or small gravel.

  • Crucial: Keep the mulch about 2-3 inches away from the crown (base) of the plant to prevent moisture buildup, which can lead to rot. The goal is to insulate the roots, not suffocate or rot the crown.

  • Avoid heavy, moisture-retaining mulches like shredded wood mulch or leaves piled directly against the plant, especially in areas with wet winters, as these can hold too much moisture.

• Snow Cover: In regions with consistent snow, snow itself acts as an excellent insulator. A good blanket of snow can protect lavender from extreme cold.

• Wind Protection: In very windy areas, especially for more tender varieties or young plants, a temporary burlap screen on the windward side can help protect against dehydrating winter winds.

3. Winterizing Container-Grown Lavender

Lavender in pots is much more vulnerable to winter cold than in-ground plants because their roots lack the insulation of the surrounding soil. The soil in pots also freezes and thaws more rapidly.

• Move to a Sheltered Location: This is the most effective strategy.

  • Unheated Garage, Shed, or Cold Frame: Ideal places where temperatures stay cool but above freezing (e.g., 35-45°F or 2-7°C). Ensure some air circulation. Water very sparingly, only when the top inch or two of soil is completely dry.

  • Covered Porch or Against a House Wall: In milder zones, simply moving the pots to a sheltered spot against a warm building (south-facing wall is best) can provide enough protection from wind and direct cold. Grouping pots together also offers mutual insulation.

  • Bury the Pot: In moderately cold zones, you can dig a hole in the ground and bury the entire pot (up to the rim) in a well-draining spot. This leverages the insulating power of the earth.

• Bringing Indoors (Living Space):

  • If bringing into a heated home, choose the coolest, brightest spot available (e.g., a south-facing window).

  • Acclimatization: Gradually transition the plant indoors over a week or two by bringing it in for increasing periods each day.

  • Light: Provide as much light as possible. Supplemental grow lights might be necessary, as indoor light is often insufficient, leading to leggy growth.

  • Temperature: Avoid placing near heat vents or fireplaces. They prefer cooler indoor temperatures (e.g., 50-65°F or 10-18°C) during their dormant period.

  • Watering: Drastically reduce watering. Wait until the top 1-2 inches of soil are completely dry. Overwatering is the biggest risk indoors.

  • Humidity: Indoor air can be very dry. While lavender likes dry air, extreme dryness can stress it. A humidity tray (pebbles and water) can help, but ensure the pot isn't sitting in the water. Good air circulation is still important.

• Insulation for Pots: If leaving pots outdoors in exposed areas, you can:

  • Wrap the pot with burlap, bubble wrap, or old blankets.

  • Place the pot inside a larger pot and fill the gap with straw, leaves, or shredded newspaper for insulation.

  • Elevate the pot slightly off cold concrete with pot feet to improve drainage and prevent freezing to the surface.

• Variety Selection: For containers, especially if you plan to keep them outdoors, choose very hardy English lavender varieties.

By taking these steps appropriate for your climate and cultivation method, you can significantly increase the chances of your lavender plants successfully overwintering and thriving again next spring.