What’s involved in overwintering annuals that you’d like to bloom next year like geraniums and tuberous begonias?
For geraniums, can you simply shake them dry and hang them up in the basement?
For tuberous begonias, is there an easy way to overwinter them that isn’t too involved (and that requires keeping the temperature and the humidity just right)?
There are tried and true methods for overwintering geraniums (Pelargonium) and tuberous begonias — and what an excellent way to save those beautiful plants you enjoyed last summer.
For geraniums, your friend was right that it is possible to shake the soil off their roots and hang them up in the shed or the basement, as long as the place you choose is cool but frost-free. But if you don’t want to have them literally hanging around, you can wrap them in newspaper and place them in a cardboard box. This solution of overwintering them in a semi-dormant state is one method.
Another is taking cuttings, which takes up even less space. But if you have the space and you want a few blooms over the winter, you can always bring your plants indoors in their original pots. See “Wintering Geraniums” on the TMG website for more information on these other methods. https://www.torontomastergardeners.ca/index.php/askagardener/wintering-geraniums/
However they’ve been overwintered, once the geraniums show early signs of growth in the spring, soak their roots in water for a few hours, and then pot them up, cutting back the stems to about 4 inches (10 cm). Keep them inside until there’s no danger of frost.
For further information see
Tuberous begonias need to be dormant over the winter. It is a normal part of their life cycle. It is possible to grow them indoors over the winter under perfect conditions, but it is difficult to keep light and humidity at the ideal levels so they can thrive. The easier method is to dry and store them.
Here’s what the TMG suggests:
“Your begonias can be dug up in fall once the foliage has faded or just after the first light frost. Spread the begonia clumps on newspaper and leave them in a sunny spot for about a week until they are completely dry. Cut off any remaining foliage and gently shake off any soil still clinging to the tubers.To prevent problems with fungus or powdery mildew while wintering your begonias, dust the tubers with sulphur powder before you put them away. Store the begonia tubers individually in paper bags or place them in a single layer on newspaper in a cardboard box in a cool, dark, dry location. Make sure you do not store them in plastic. They need to breathe and stay completely dry.”