Geraniums react to temperatures below five degrees Celsius with pauses in their growth. Frost can cost them their lives, and it can be frosty in the UK until May depending on where you live.
In this article, we show you 7 ways to protect geraniums from the cold.
Tipp 1: Don't buy geraniums at the beginning of April
The earlier you bring the plants home, the longer you have to watch out for the weather and the greater the risk that they will suffer from cold damage. Although it depends on where you live and how quickly summer comes, we advise you not to buy your geraniums too early.
As long as they are still in the greenhouse, they will be well cared for.
The alternative to outdoor geraniums is noble geraniums! They grow well indoors and provide summer flair early in the year.
If you don’t want to wait, you will have to provide protection from the cold sooner or later. We will now explain how to do this.
Place the geraniums close to the outside walls of the house
In this location, the waste heat from the house will help you to make the temperatures bearable for the plants.
Walls are heat accumulators. They balance out the differences between the temperatures during the day and at night.
Tipp 3: Do not place the geraniums directly on the ground
Cold air moves downwards and collects on the ground. This is why there is often a frost on the ground in late spring, even when it is no longer freezing at eye level. Put your boxes and tubs of summer flowers on boxes, tables, or benches and save them from the cold air.
Tipp 4: Put a roof over the geraniums
As we explained in Tip 2, cold air moves downwards and collects there. If the geraniums are under a roof, the cold air does not fall directly onto the plants. However, it can still flow in from the side near the ground, so remember to place the geraniums higher up!
Tipp 5: Cover the geraniums in the evening
A garden fleece or a bed sheet keeps the cold away from the plants at night. A cardboard box placed over boxes and tubs also works. Remove the protection during the day so that the geraniums get enough light. If that sounds like too much work, the garden fleece can be left on the plants during the daytime as well.
Tipp 6: Move the geraniums out of the wind
Do you remember those winter days, when the icy wind cut into your face? Maybe it wasn’t even below zero degrees, but the air felt like it was covered with a thousand tiny, frosty needles. Geraniums have a similar experience when they hang unprotected in their boxes on the balcony railing when there is 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 wind from coming into contact with the leaves. This helps the geraniums to survive cool temperatures. If there is a threat of frosty nights, it is better to remove the boxes. Cover them and place them in an elevated position, as close as possible to the outside walls of the house.
Tipp 7: Bring the geraniums inside
If there is an unexpected cold snap where all the measures described so far do not help, you have no choice but to move the geraniums indoors temporarily. They will survive a few days in a garage or a frost-free garden shed.
What if my geraniums have been exposed to frost?
If your geraniums have suffered a light frost, usually the damaged areas will eventually grow back. Simply remove any leaves that have been damaged by the frost and pay more attention to the weather forecast from now on. If the stems and roots are intact, the plants will regenerate.
In late spring it is not worthwhile to protect geraniums from frost. If you want to overwinter them, bring them in as late as possible but before the first frost. Cut back the shoots about a hand’s width, remove damaged foliage and keep the geraniums as cool as possible. You hardly need to water them in winter.
Why don‘t geraniums tolerate frost?
Geraniums do not tolerate frost because this is not necessary in their natural habitat. The region around Table Mountain in South Africa is home to the ancestors of these ornamental plants. It rains little there, and the average annual temperature is 25 degrees Celsius. It hardly ever freezes in winter. By comparison, the average annual temperature in the UK is around 9.6 degrees Celsius. The Isles of Scilly have the highest mean annual temperature in the UK, of 11.5 degrees Celsius!