Overwintering Pelargoniums Indoors: A UK Grower's Guide

Introduction

Pelargoniums (commonly called geraniums) are not hardy in the UK — a single hard frost will kill them outdoors. But every year, thousands of gardeners bin healthy plants in October that could easily live for 5–10 years if overwintered correctly. The good news: you don't need a heated greenhouse. A bright windowsill, the right prune, and a careful watering schedule are all it takes. This guide is the exact method we use at Home Gardening Pedia, refined over multiple UK winters.

When to Lift Your Pelargoniums

The trigger date is when night temperatures regularly drop below 5°C — typically late September in northern England and Scotland, mid-October in the south, and right at the end of October in coastal and London gardens. Don't wait for a frost warning; pelargoniums are damaged by cold long before they freeze, and the leaves will start yellowing as a warning. Lift on a dry day so the rootball isn't waterlogged going into storage.

The Lift-and-Prune Method

Winter Care: October to March

• ✓ Water sparingly — once every 3–4 weeks is usually enough
• ✓ Only water when the top 3cm of compost is bone dry
• ✓ Never let water sit in the saucer — empty after 10 minutes
• ✓ Pinch off any sad-looking yellow leaves as they appear
• ✓ Check weekly for grey mould (botrytis) and remove affected stems immediately
• ✓ Do NOT feed at all during the dormant period

Bringing Them Back in Spring

From early March, gradually move plants to a brighter, warmer spot and increase watering. You'll see new buds breaking from the woody stems within 2–3 weeks. Start a weekly half-strength tomato feed in late March to encourage strong, flowering growth. Pot on into fresh compost in a slightly larger container in early April. Don't move plants outdoors until all risk of frost has passed — typically mid to late May in the UK, even later in Scotland and northern England.

Two Alternative Methods

Best Kit for Overwintering Pelargoniums

The right gear makes overwintering far more reliable. Four products we recommend specifically for this job: Westland Houseplant Compost (free-draining, ideal for the lift-and-pot method), Burgon & Ball RHS Pruning Snips (clean cuts that heal faster, reducing rot risk), GardenSkill Heavyweight Horticultural Fleece (for late-October emergency frost protection if you can't lift in time), and a basic XLUX T10 Moisture Meter (the single best tool to stop overwintering rot — you only water when it reads 'dry'). Together these four cost less than replacing 3–4 plants in spring.

Common Overwintering Mistakes

• ✗ Leaving plants outdoors until the first frost — damage starts much earlier
• ✗ Skipping the hard prune (the #1 cause of weak, leggy spring plants)
• ✗ Overwintering in a warm, centrally-heated room (causes weak growth and aphids)
• ✗ Watering on a fixed schedule instead of checking the soil
• ✗ Using a pot that's too big — wet compost around dormant roots causes rot
• ✗ Bringing plants outdoors too early in spring before frost risk has passed

Frequently Asked Questions