Overwintering geraniums

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Geraniums (Pelargonium) are favorite annual flowers in Minnesota. Easily grown in planting beds, pots, window boxes or hanging baskets, annual geraniums can also be overwintered.

If you have included geraniums in your garden this year, you might be considering bringing them indoors to save for next year’s garden. There are several options for accomplishing this. Geraniums can be overwintered indoors by taking cuttings, potting up individual plants or storing bare-root plants in a cool, dry location. Make sure to do one or all of these things before the first frost.

Take geranium cuttings

• Take 3- to 4-inch stem cuttings from the tips of the plant.
• Remove the lower leaves and dip the base of each cutting in a rooting hormone.
• Stick the cuttings into a pot or flat with drainage holes containing vermiculite or a mixture of perlite and sphagnum peat moss.
• Insert the cuttings into the growing medium far enough to stand on their own.
• Water the container after all the cuttings are inserted.
• Allow the medium to drain for a few minutes, then place a clear plastic bag or dome over the cuttings to prevent the plant foliage from wilting.
• Place the cuttings in bright, indirect light.

They should root in six to eight weeks. When the cuttings have good root systems, remove them from the rooting medium and plant each rooted cutting in its own pot. Place the potted plants in a sunny window or under artificial lighting until spring.

Overwinter geraniums as potted plants

• Dig up each plant you want to save, making sure to get most of the root ball, and place in a large pot.
• Water thoroughly, then place the plants in a sunny window or under artificial lighting.
• Water plants about every two weeks.

Geraniums prefer daytime temperatures of 60 to 65 degrees F and slightly cooler nighttime temperatures. They are likely to become tall and lanky by late winter. Prune your potted geraniums in March, removing one-half to two-thirds of each plant. They will begin to grow again within a few days and should develop into attractive plants by May. 

Overwinter geraniums as bare-root plants

• Carefully dig up the geraniums before the first fall frost.
• Remove all of the soil from the plant’s roots.
• Place one or two plants in a large paper sack and store in a cool (45- to 50-degree F), dry location. Or hang the plants upside down in a cool, dry location. The foliage and the shoot tips will eventually die.

In March, remove all shriveled, dead material and prune back to firm, green, live stem tissue. After pruning, pot the plants and water thoroughly. Place the potted geraniums in a sunny window or under artificial lighting. Geraniums that are pruned and potted in March should develop into attractive plants that can be planted outdoors after the last frost.

Find out more about growing geraniums in Minnesota.