The Sauk County Gardener: How to overwinter your geraniums
“I grow plants for many reasons: To please my soul, to challenge the elements or to challenge my patience, for novelty, or for nostalgia, but mostly for the joy in seeing them grow.”— David Hobson
By Jeannie Manis
I grew up on a farm outside of Wonewoc and I remember bringing in my grandma’s geraniums every fall to overwinter in her unfinished basement. We would set them up in the basement windowsills and water them every three to four weeks. By the end of winter, they looked pretty rough. But every spring, we would take them out, trim them up and they would soon bloom another season. Overwintering your geraniums is a great option if you have a unique geranium that you’re unsure you’ll find next year, want to save some money next spring, or simply want a new learning experience or challenge. Whatever the reason, there are several techniques you can use.
Bring your geraniums in the house and treat them like houseplants.
Before the first frost, cut them back to about half their size, dig them up and plant them in a container.
Check the plant for any insects or disease. Because you are treating them like a house plant, place them in a cool location with plenty of indirect bright light. After potting them up, water them as needed. If need be, pinch the tips back to promote branching. Fertilize them lightly before planting them out next spring, typically in May.
Take cuttings from your geraniums and root them.
If you are looking to get more geraniums for next year, this is a great option to use. Take about a three-four-inch cutting from a plant’s stem tip. Dip the cut end in rooting hormone (if desired) and place it in a soil-less potting mix. Sand or perlite can be used as well. Make sure the pot has drainage holes. Put a clear plastic bag over the top of the pot to create a mini-greenhouse and set the pot in location with bright, indirect light. Once the roots about an inch long, transplant the cuttings into a three to four-inch pots and place in a sunny location and water as needed. My east-facing windows in my kitchen are perfect for this option. As the geranium grows, pinch its shoots back to force branching. To learn more about rooting plants from cuttings, visit: https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/he....
Place potted geraniums in cool storage.
This is essentially the technique my grandma used. Place the potted geranium in a cool place (like a garage or unheated basement). Remove dead or diseased plant parts and cut the plant back to a third or half. Water it deeply and place it in storage. Then throughout the winter, check it occasionally and give it a light watering. In the spring, reintroduce it to light and normal watering.
Store the bare root of your geraniums.
For this technique to work, you will need a cool, dark location that is between 45-50 degrees like a garage or unheated basement. Before frost, dig up the entire plant and shake off any excess soil. Put the plant in a brown paper bag and hang them upside down in a cool dark location where they will not freeze. A couple times over the winter, take them down and soak the roots in water for one to two hours. When you do this, also look over the plant. The stems should be firm and solid; if not, discard the plant as it most likely will not survive. Pot them up late next March or early April, water them, cut back any dead stem tips and put them in a sunny location to promote new growth. Don’t become too impatient as it can take a couple weeks to get them to come out of dormancy and start growing again.
To learn more about overwintering geraniums, check out https://hortnews.extension.iastate.edu/2004/9-17-2004/geraniums.html.
Remember to contact the University of Wisconsin Madison Division of Extension Sauk County if you have any gardening questions. Please send an email to haley.weisert@saukcountywi.gov or call the University of Wisconsin Madison Division of Extension Sauk County office at 608-355-3250.
Jeannie Manis is president of the Sauk County Master Gardeners Association (SCMGA).
