The geraniums, which bloom for many months, are popular flowers for balcony boxes and colorful flower beds. The mostly red, pink or white flowering wonders often show their splendor well into autumn – only to be transported with the first frost either in the basement to overwinter or in the garbage. Aren’t there hardy geranium varieties that can stay outside?
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Pelargoniums or geraniums?
Yes, of course some geranium varieties are hardy, some hobby gardeners will now think. After all, various discounters, hardware stores and garden centers offer new varieties every year. The problem with this: These are not the popular balcony geraniums, but similar flowering variants of the actually frost-hardy cranesbill. What are commonly sold as “geraniums” are actually pelargoniums (bot. Pelargonium). The cranesbill – geranium in Latin – is related to the pelargonium (or balcony geranium), but comes from different climate zones and therefore has a completely different winter hardiness.
Not hardy: balcony geraniums
So “geranium” is just the slang term for flowering plants, which are correctly called pelargoniums – and these are definitely not hardy. The majority of the approximately 220 different species of this genus, which belongs to the cranesbill family (bot. Geraniaceae), come from warm South Africa and are therefore naturally used to a climate similar to that of the Mediterranean. In Central Europe, on the other hand, the plants are not hardy, they survive temperatures of a maximum of minus five degrees Celsius for short periods. You should therefore move the plants to their winter quarters in good time before the first frost.
Hardy geranium varieties
However, there is one exception: the geranium Pelargonium finiterianum, which originates from the limestone mountains of Turkey, is considered conditionally hardy due to its origin. In order for the species to survive the cold season here, the following conditions should be met:
- dry ground
- no moisture, especially no waterlogging
- Temperatures up to minus 12 °C
- Prune the plant in the fall
- cover with brushwood, straw or other protection over the winter
This species becomes problematic if the winter is very cold over a longer period of time with temperatures significantly lower than minus 12 °C or if it is very wet. In both cases, it is advisable to either provide the plant with appropriate protection or to dig it up and bring it indoors to overwinter. But here, too, the species needs a cool hibernation, otherwise it will not form any flowers.
Hardy replacement: Geranium himalayense
Instead of the Pelargonium species that are difficult to overwinter, the Himalayan cranesbill (bot. Geranium himalayense), which also blooms profusely and permanently, is suitable for planting in containers and beds. As the name suggests, the perennial species comes from the Central Asian Himalayas and is therefore naturally well prepared for Central European winters. You need during the cold season:
- no winter protection
- a slightly moist soil
- no moisture, especially no waterlogging
In particular, the newly bred varieties ‘White Snow Double’, ‘Red Burcs Double’ and ‘Blue Birch Double’ look very similar to those of pelargonium with their double flowers that appear again and again throughout the summer months.
Overwinter geraniums properly
If you still prefer to enjoy the flowering splendor of the balcony geraniums, this is the best way to get the plants through the winter like this:
- Put in before the first frost
- Place containers planted purely with geraniums in winter quarters like this
- Location as bright and cool as possible
- Temperatures between five and a maximum of ten degrees Celsius
- do not fertilize, water very little
Overwinter pelargoniums in a dark place
The following form of hibernation is more space-saving:
- Cut flowers back heavily
- leave no leaves on the plants
- Lift plants out of the planter
- remove all soil
- Wrap bare root plants in newspaper
- winter dark and cool
- occasionally spray with water
From February, plant the overwintered flowers in fresh substrate and pull them up on the windowsill. However, the plants only come outside after the ice saints, when the danger of night frosts has passed.