Overwintering Geraniums UK: The Best Methods to Keep Your Plants Alive Through Winter

Introduction

Overwintering geraniums in the UK is essential to protect these tender perennials from frost. While geraniums thrive in warmer months, they struggle to survive in cold UK winters, making it important to take the right steps to store and protect them.

Instead of letting your geraniums die from frost, you can bring them indoors, store them dormant, or use greenhouse protection to ensure they bloom again in spring.

In this comprehensive guide, we’ll cover:
✅ The best methods for overwintering geraniums in the UK
✅ How to store geraniums indoors or in a greenhouse
✅ The right way to prune and prepare plants for winter
✅ Common mistakes to avoid
✅ Expert tips for strong growth in spring

Why Overwinter Geraniums in the UK?

Geraniums (Pelargoniums) are not frost-hardy and will die if left outdoors in UK winters. Overwintering them allows you to:
🌱 Save money by keeping plants for next year instead of buying new ones.
🌸 Enjoy bigger, stronger blooms from mature plants in spring.
❄️ Prevent frost damage and ensure healthy regrowth.

💡 Tip: If UK temperatures drop below 5°C (41°F), you need to overwinter your geraniums.

Best Methods for Overwintering Geraniums in the UK

1. Keeping Geraniums as Houseplants (Best for Potted Geraniums)

✅ Step 1: Bring Plants Indoors Before Frost

• Move geraniums inside before temperatures drop below 5°C (41°F).
• Keep in a cool, bright spot (10-15°C / 50-60°F) such as a sunny windowsill, porch, or conservatory.

✅ Step 2: Reduce Watering

• Water only when the soil is dry to prevent rot.
• Avoid overwatering, as indoor geraniums need less moisture in winter.

✅ Step 3: Trim Back the Plant

• Cut stems by one-third to prevent legginess.

💡 Tip: Use a south-facing window or LED grow lights to ensure healthy indoor growth.

2. Storing Geraniums Dormant (Best for Bare-Root Storage)

✅ Step 1: Lift Geraniums Before the First Frost

• Carefully dig up geraniums and shake off excess soil.

✅ Step 2: Trim & Dry the Plants

• Cut stems down to 10-15 cm (4-6 inches).
• Let plants air dry for 24 hours in a cool place.

✅ Step 3: Store in a Cool, Dry Place

• Hang upside down or place in a box lined with newspaper.
• Keep at 5-10°C (41-50°F) in a garage, basement, or shed.

✅ Step 4: Check Tubers Monthly

• Mist lightly if stems start drying out.

💡 Tip: Replant geraniums in March-April, watering them well to encourage new shoots.

3. Keeping Geraniums in a Greenhouse (Best for Large Plants)

✅ Step 1: Move Potted Geraniums to a Greenhouse

• A heated greenhouse is ideal, but an unheated greenhouse needs extra insulation.

✅ Step 2: Trim Back Growth

• Cut plants back to half their size to reduce stress.

✅ Step 3: Water Occasionally

• Water once a month to prevent drying out.
• Avoid overwatering, as cold damp soil can cause root rot.

✅ Step 4: Insulate the Greenhouse in Freezing Temperatures

• Use bubble wrap, fleece, or straw for extra protection.

💡 Tip: If temperatures drop below freezing (-2°C or lower), move geraniums indoors or provide a small greenhouse heater.

When to Bring Geraniums Back Outside in the UK

✅ Late March – Early April: Start watering more frequently to encourage new growth.
✅ April – May: Move plants outdoors gradually to harden them off.
✅ After the last frost (typically May): Replant into borders, containers, or hanging baskets.

💡 Tip: Apply a slow-release fertilizer when replanting to boost flowering.

Common Mistakes to Avoid When Overwintering Geraniums

🚫 Bringing plants inside too late – Always move them before frost arrives.
🚫 Overwatering dormant geraniums – This leads to root rot.
🚫 Storing in a too-warm area – They need a cool but frost-free space.
🚫 Forgetting to check stored plants – Inspect monthly for dryness or mold.

💡 Tip: If leaves turn yellow, your geranium is getting too much moisture or not enough light—adjust care accordingly.

Conclusion

Overwintering geraniums in the UK is easy and cost-effective, allowing you to keep plants alive through winter and enjoy bigger, healthier blooms next year.

Whether you bring them indoors, store them dormant, or use a greenhouse, these simple steps will ensure successful overwintering and a thriving garden in spring.