November 5, 2015 – Kenosha News
Question: Are there instructions for overwintering large geraniums plants. A friend told me to put the plant in a paper bag and hang them in the utility room. Anything more scientific than that? M.K.
Answer: I’m assuming the geraniums you are asking about are the bright red or pink flowered type that won’t survive our Wisconsin winter outdoors. Botanically, these plants are Pelargonium – true geraniums are garden perennials – and can be overwintered three ways.
The paper bag hanging method recommended by your friend depends on your home. Modern homes are usually too warm and dry, but if your house has a cool (45 to 50 degrees), moist basement or fruit cellar give it a try. Remove the geranium from its pot and gently shake off all soil. Hang the plants upside down from rafters or wires in a cool dark area. Two or three times during the winter take the plants down and soak the roots in water for 1 to 2 hours, then re-hang. The leaves will drop off but the stems should remain firm. Re-pot in early April, move to sunny window, and keep watered. It will take several weeks for new growth to begin.
Another way is to leave the geraniums in their pots and care for them like other houseplants. Shortly after bringing indoors, trim the plants back by one-half to one-third their original size. Cut the stems just above a leaf. Geraniums should be grown in a cool room with lots of bright direct sun. Water when the soil is dry to touch. Do not overwater. During the winter you may need to pinch back new grow to shape the plants and remove weak sprouts. Fertilize once a month with a general houseplant fertilizer at half the rate recommended.
Geraniums are easy to root by stem cutting. Use a knife to cut 3 to 4 inch long stem tips from the healthiest plants. Pull off all the leaves on the lower half of the stem. Dip the lower end of the cutting in a rooting hormone powder. Tap off excess powder. Insert the lower half of the cutting in a well-drained potting soil. You can use pots or flats. Cover everything with a plastic bag to keep humidity high around your cuttings. Keep in bright, indirect light and water to keep the soil moist. After six to eight weeks your cutting should have roots and may be transplanted into larger pots. Care for your new plants as described above.
Barb Larson is horticulture educator for the Kenosha County University of Wisconsin Extension. She holds a master’s of science in horticulture from the University of Wisconsin-Madison. If you have a plant or gardening question, email her at firstname.lastname@example.org or call 262-857-1942.