In the garden I've planted various perennial hardy geraniums (cranesbills); I have two scented geraniums in large pots (Pelargonium quercifolium "Royal oak" and Pelargonium capitatum "Attar of roses"); and in both the garden and at home on our balconies I have a number of the traditional balcony pelargonium geraniums.
Each of these members of the Geraniaceae family needs different treatment to survive the winter in the latitude where we live.
Hardy geraniums are, as the name implies, perennials in Central Europe and can just stay put through the winter, although some of mine made it through their first winter better than others.
Pelargonium geraniums cannot survive outside, and up till now I've just let them die and replaced them in the spring. The city of Mannheim sponsors a geranium market each spring in the city's central square, and we enjoy purchasing new petunias and geraniums for our balconies there each year.
This year, however, I really liked some of my pelargoniums, both the brilliant red ones on the balconies and a small bed of variegated ones in the potager (sorry no photos), and felt bad about just disposing of them on the compost heap. Secondly, a dear elderly gardening friend of mine was very keen on imparting her knowledge of overwintering geraniums to me. So I consented and here's the method she taught me:
The first step was to remove the plants from their pots/beds before frost set in and place them in cardboard boxes indoors. There they were to remain until the earth on the roots dried completely and the plants themselves became limp and "floppy". This took a couple weeks.
The next step was to shake all the earth out of the roots, clip off any overly long roots, break off all the blossoms and strip off any dead or wilted foliage. The result looks like this:
This makes rather a mess, and a pile of earth and foliage is leftover, so be sure you do this on newspaper!
After this, the plants are carefully packed in several layers of newspaper, and then sealed with packing tape.
Thus prepared, they can be stored in the cellar or even, in my case, in the unheated garden cottage in a cupboard, until spring. They need no water or light until then. In the spring they are replanted in their pots or in the ground whenever it's reliably warm. Here that's the end of April or after the "frost saints" in mid-May.
Scented geraniums also cannot survive the winter outdoors and are simply left in their pots and placed indoors in a cool, frost-free place and watered very sparsely until spring. Because of the consistency of their roots, the "packing" method doesn't work with them. This is unfortunate, as it takes up much more space to store them. I was able to store 15 "packed" geraniums on a small shelf.
I know from browsing and books that there are other methods for overwintering geraniums, but my gardening mentor has been using her method successfully for over 60 years, and that inspires absolute confidence!
I am looking forward to having the rose-scented geranium next to the swing again next summer,
and to having the oak-scented geranium next to the birdbath in the potager (the oak-scented one didn't bloom much, but the foliage was very strongly scented). I had it there in hopes that it would discourage mosquitos from using the birdbath, although changing the water every day was certainly more effective.
I'd love to hear about the methods anyone else uses for overwintering their various kinds of geraniums.