As soon as the sun comes out and the days get longer again, your green fingers start itching. How tempting to plant your balcony and patio with summer flowers at the start of May! You’ve been able to buy geraniums in the shops for weeks. However, it may not be a good idea to grab them just yet. If temperatures are too low, you risk them developing late or even dying.
Geraniums react to spring temperatures below 5°C with a pause in growth and frost can kill them. And it can be frosty in the UK until after mid-May.
What to do: We share 7 ways to protect geraniums from the cold.
Tip 1: Don't buy geraniums in early April!
The earlier you bring your plants home, the longer you have to keep an eye on the weather. And the higher the risk of them suffering cold damage. It depends on where you live and how quickly summer arrives in your area, but we advise you not to buy geraniums too early. While they are still in the nursery, they will receive the best possible care.
The alternative to geraniums for outdoors: Regal pelargoniums! They grow well indoors and create a summer feel from March onwards.
If you absolutely don’t want to wait, sooner or later you’ll have to provide protection from the cold. We explain what this might look like.
Tip 2: Place geraniums close to the house wall!
There, the waste heat from the building helps make the temperature tolerable for the plants. Walls are heat stores. They help equalise the differences between daytime and nighttime temperatures.
Tip 3: Don't place your geraniums on the ground!
Cold air sinks and collects there. This is why there’s often frost on the ground in late spring, even if it has long since stopped freezing at eye level. Place your summer flower boxes and containers on crates, tables and benches and save them from this ‘cold air lake’.
Tip 4: Put your geraniums under cover!
As explained in Tip 2, cold air sinks and collects on the ground. If your geraniums are under a shelter, the cold air doesn’t fall straight onto your plants. It will flow in from the side near the ground, so remember to put your geraniums higher up!
Tip 5: Cover your geraniums at night!
A garden fleece or a bedsheet will keep the cold away from your plants at night. A cardboard box placed over pots and containers also works. Remove the protection during the day so your geraniums get some light. Too much work? Garden fleece can be left on.
Tip 6: Keep your geraniums out of the wind!
Remember those winter days when icy wind cuts across your face? Maybe it wasn’t even freezing, but the air felt like it was filled with a thousand tiny, frosty needles. Geraniums feel the same way when they hang, unprotected, in their boxes on a balcony railing when there’s a risk of frost.
Of all the places around the house, a balcony railing is probably the most exposed to wind and weather. Use a garden fleece to keep the breeze from coming into contact with the leaves. This helps your geraniums withstand colder temperatures. If there’s the risk of crisp, frosty nights, it’s better to take the boxes down. Cover them and place them as close to a house wall as possible.
Tip 7: Bring your geraniums inside!
If the weather goes crazy and there’s a cold snap and all the measures described so far don’t help, you have no choice but to bring your geraniums inside temporarily. They will survive a few days in a garage, cool porch or frost-free shed.
What if it does happen?
If your geraniums have suffered a light frost, there’s usually no damage that won’t eventually grow back. Simply remove any frost-damaged leaves and monitor the weather forecast more closely from now on. If the stems and roots are intact, the plants will recover.
In autumn, it’s not worth protecting geraniums from frost. If you want to overwinter them, bring them in as late as possible, but before the first frost. Cut the shoots back to about the width of your hand, remove damaged foliage and keep them as cool as possible. You hardly need to water them at all in winter. Stop fertilising completely.
Why don't geraniums withstand frost?
Geraniums can’t withstand frost because they don’t need to in their natural habitat. The region around Table Mountain in South Africa is home to the ancestors of our ornamental plants. It rains very little there and the average annual temperature is 25°C. It hardly ever freezes in winter.
For comparison: In 2023, the town of Waghäusel near Karlsruhe was the warmest place in Germany with an average annual temperature of 13.1°C. The average annual temperature in Frankfurt was 12.5°C and 10.1 °C in Lüdenscheid.
Geranium planting made easy
Perfect conditions in a balcony box are the basis for a summer full of flowers. We explain how to plant balcony boxes with geraniums like a pro. Step by step. With a shopping list. And there’s plenty of background knowledge too. Read, get stuck in, enjoy!
