What is Overwintering? A Complete Guide to Protecting Plants in Winter

Introduction

Overwintering is the process of helping plants survive cold winter conditions by providing protection, storage, or specialized care. Many plants, especially tender perennials, bulbs, and vegetables, cannot withstand frost and freezing temperatures without proper overwintering techniques.

By overwintering plants correctly, you can save money, maintain healthier plants, and enjoy earlier blooms in spring.

In this comprehensive guide, we’ll cover:
✅ The meaning of overwintering and why it’s important
✅ Which plants need overwintering
✅ The different methods of overwintering plants
✅ Common mistakes to avoid
✅ Expert tips for ensuring plants thrive after winter

What Does Overwintering Mean?

Overwintering refers to protecting plants from winter weather to ensure they survive and regrow when temperatures rise. This can involve:
❄️ Bringing tender plants indoors to prevent frost damage.
🪴 Storing bulbs or tubers in a dry, frost-free location.
🌱 Using insulation methods like mulch, fleece, or cloches to shield outdoor plants.
🏡 Keeping plants in a greenhouse with temperature control.

💡 Tip: Overwintering allows plants that are not naturally hardy to be saved and replanted each year instead of buying new ones.

Why is Overwintering Important?

🌱 Protects plants from frost and freezing – Essential for non-hardy perennials, tropical plants, and some vegetables.
💰 Saves money – Instead of replacing plants every spring, you can reuse tubers, bulbs, and stored plants.
🏡 Extends the growing season – Overwintered plants start earlier in spring for faster blooms and harvests.
💪 Stronger, healthier plants – Older plants develop bigger roots and better resistance to pests and diseases.

💡 Tip: Overwintering is especially useful for gardening in cold climates where winter temperatures regularly drop below 0°C (32°F).

Which Plants Need Overwintering?

Some plants can survive cold temperatures, while others need extra protection or indoor storage.

1. Tender Perennials (Need Protection or Indoor Storage)

🚫 Cannot survive frost without overwintering.
✅ Geraniums
✅ Begonias
✅ Dahlias
✅ Fuchsias
✅ Canna lilies

💡 Tip: Store tubers, bulbs, and rhizomes indoors or keep potted plants inside.

2. Hardy Perennials & Shrubs (Benefit from Mulching or Covering)

🌿 Can survive winter but need extra insulation in very cold climates.
✅ Lavender
✅ Rosemary
✅ Strawberries
✅ Figs

💡 Tip: Use mulch, straw, or fleece to insulate roots and branches from extreme frost.

3. Vegetables for Overwintering (Cold-Hardy Crops)

🥕 Planted in autumn for an early spring harvest.
✅ Onions
✅ Garlic
✅ Kale
✅ Carrots
✅ Leeks

💡 Tip: Use cloches or row covers to shield young plants from snow and frost.

4. Greenhouse or Indoor Overwintering Plants

🌱 Best kept in a greenhouse or indoors over winter.
✅ Tomatoes (if grown as perennials)
✅ Chili peppers
✅ Citrus trees
✅ Orchids

💡 Tip: Keep greenhouse temperatures above 5°C (41°F) to prevent plant stress.

Different Methods of Overwintering Plants

1. Bringing Plants Indoors (For Houseplants & Tender Perennials)

✅ Move plants inside before the first frost.
✅ Place in a cool, bright location (10-15°C / 50-60°F).
✅ Water sparingly—only when soil dries out.

💡 Tip: Avoid placing near radiators or direct heat sources, which can dry out plants.

2. Storing Bulbs & Tubers Dormant (For Begonias, Dahlias, Cannas, etc.)

✅ Dig up tubers before the first frost.
✅ Trim stems to 10-15 cm (4-6 inches).
✅ Dry for 24-48 hours, then store in a cool, dry place (5-10°C / 41-50°F).
✅ Use newspaper, dry compost, or sawdust for insulation.

💡 Tip: Check stored tubers monthly for mold or shriveling, misting lightly if too dry.

3. Outdoor Protection with Mulch & Covers (For Hardy Plants & Root Crops)

✅ Apply 5-10 cm (2-4 inches) of mulch around plant bases.
✅ Use straw, compost, bark, or shredded leaves for insulation.
✅ Cover small plants with horticultural fleece or cloches.

💡 Tip: Remove excess mulch in early spring to allow new growth.

4. Overwintering in a Greenhouse or Polytunnel

✅ Move plants inside before temperatures drop below 5°C (41°F).
✅ Keep greenhouse temperature between 5-10°C (41-50°F).
✅ Water less frequently to prevent rot.
✅ Use bubble wrap insulation or heating mats if needed.

💡 Tip: A small paraffin or electric heater can keep a greenhouse frost-free.

Common Mistakes to Avoid When Overwintering Plants

🚫 Waiting too long to bring plants inside – Move them before the first frost.
🚫 Overwatering stored plants – Keep soil dry to prevent rot.
🚫 Storing bulbs while still damp – Dry thoroughly to avoid mold.
🚫 Using plastic covers without airflow – This traps moisture, causing fungal diseases.
🚫 Forgetting to check stored plants – Inspect monthly for rot or dehydration.

💡 Tip: If a stored bulb or tuber feels soft and mushy, discard it to prevent disease spread.

Final Tips for Successful Overwintering

🌡 Monitor temperatures – Keep plants at the correct overwintering temperature.
🏡 Choose the right method – Some plants need indoor storage, while others need mulching.
💦 Water less frequently – Most overwintering plants need minimal moisture.
🌞 Give light where needed – Houseplants still need bright, indirect light.
🌱 Check plants monthly – Prevent rot, mold, or dehydration.

💡 Tip: In spring, gradually reintroduce plants to outdoor conditions to avoid transplant shock.

Conclusion

Overwintering is a simple but essential gardening practice that protects plants from cold temperatures, frost, and harsh winter conditions.

By using the right method—whether indoor storage, mulching, or greenhouse protection—you can save plants, reduce costs, and enjoy healthier growth in spring.

Whether you’re overwintering tender perennials, root crops, or greenhouse plants, following these expert tips will ensure a thriving garden year after year!