Geraniums cope well with heat, but not with frost. On Spain’s Mediterranean coast and in the Canary Islands they can spend the winter on the balcony with almost no care; in Madrid, across the two Castiles or in the north, a single night below freezing can kill them. If you’re wondering how to overwinter geraniums, the good news is that they’re perennials: with a few simple steps they’ll flower again in spring, often more vigorously than a newly bought plant.
When to protect geraniums
Get started when night-time lows begin to drop below 5 °C. In inland Spain this usually happens between late October and November. Check the overnight forecast, not the midday temperature: a light frost is enough to scorch leaves and stems.
Before you put them away: clean-up and pruning
- Remove flowers, buds and yellow leaves so the plant doesn’t waste energy on flowering.
- Cut the stems back by a third to a half, leaving several nodes on each one (the points where the leaves grow from).
- Check the undersides of the leaves and the stems. If you see aphids or whitefly, treat them before bringing the pot indoors so they don’t spread to other plants. If a stem has holes in it or is hollow, it may be the caterpillar of the geranium bronze butterfly: cut that part off.
- Water less in the days before: slightly dry soil reduces the risk of the stems rotting.
Method 1: how to overwinter geraniums in a bright, cool spot
This is the safest option. The geraniums stay in their pot or window box, somewhere with plenty of light and a cool temperature, ideally between 5 and 10 °C: a conservatory, an enclosed terrace, a landing with a window or a bright storeroom, as long as it doesn’t freeze. Water sparingly, just enough to stop the root ball drying out completely (usually every two or three weeks), and don’t feed until spring. Pick up fallen leaves to prevent fungal problems.
If all you have is a heated home, place them by the coldest window and away from radiators. In warmth and low light the stems grow long and thin, but the plant usually survives; a harder prune in spring will be enough.
Method 2: bare-root in a dark, frost-free place
If you don’t have a bright corner but do have a dry garage or cellar that never freezes (around 5-8 °C), you can store the geraniums dormant:
- Take them out of the pot and gently shake the soil off the roots.
- Cut the stems down to about 15 cm and remove all the leaves.
- Wrap the roots in newspaper or put each plant in a paper bag. You can also hang them upside down, with the roots facing up.
- Check them once a month: remove anything that’s rotting and, if the roots are very dry, mist them with a little water.
This method saves space, but some plants may not make it through the winter. That’s why it’s worth combining it with cuttings.
Method 3: geranium cuttings
If you’re short on space, keep cuttings instead of whole plants. Cut healthy tips 8 to 10 cm long, remove the lower leaves and the flowers, let the cut end dry for a few hours and plant them in small pots of moist seed compost (or compost mixed with sand). Put them on a bright windowsill and water in moderation. The best time is late summer, but they usually root in autumn too, just more slowly.
If they stay outside
In areas with mild winters they can stay on the balcony. Move them up against the wall of the house, in the corner most sheltered from the wind, raise the pots off the ground on a few blocks and, on nights when frost is forecast, cover them with horticultural fleece. Water in the morning, never in the evening.
What to do in spring
In late February or March, prune the stems back to two or three buds, repot in fresh compost and move the plant somewhere warmer and brighter. Increase watering gradually and start feeding when new leaves appear. Put them outside once there’s no longer any risk of frost; in inland Spain, usually between April and May.
Geraniums and pets
If your geraniums spend the winter indoors, keep your dog or cat in mind. The ASPCA, the American animal welfare organisation, lists geraniums among the plants that are toxic to dogs and cats: eating or touching the plant can cause vomiting, loss of appetite, lethargy or skin irritation. Keep them out of your pet’s reach and pick up any fallen leaves. And if you’re looking for things that make life at home with a dog or cat easier, take a look at our shop.