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Thursday, Sept. 18, 2008 06:02 am

Take your geraniums with you into winter

A summer staple across the world, geraniums are easy to grow in a window box, in patio containers or integrated into an annual garden.

Are you sad at the thought that your cheery geraniums will soon fall victim to winter frost? Why not take them inside for the winter? Gardeners have several alternatives, including potting the plants, taking cuttings from them, or storing the plants as bare-root specimens.

It's important to make sure that the plants are vigorous, healthy, and insect- and disease-free. White flies, aphids, and mealy bugs, often hide on the plants; these will spread indoors, where predators can't keep them in check. Consider repotting the geranium in fresh houseplant soil, which practically guarantees no soil-borne insects are brought indoors.

For plants in larger pots or in the ground, carefully dig up the geranium and plant it in a 6- or 8-inch pot. Prune back each plant by half.

Geraniums require at least 10 to 12 hours of light and temperatures of 65 to 70 degrees during the day and 55 to 60 degrees at night. Excessively warm temperatures tend to encourage legginess.

The approach of taking cuttings permits the use of smaller plants that take up less space and have a better chance of acclimating to indoor light, temperature, and humidity levels. Take 4 to 6 inches of terminal growth and strip off the bottom 2 or 3 inches of leaves. Dip each cutting in a rooting hormone. Stick the cuttings in sand, perlite, or vermiculite up to the first set of leaves. Water thoroughly and place in a bright, sunny window or under fluorescent lights. Cuttings should root in one or two months. When rooted, pot in a 3- or 4-inch pot and continue to grow until spring.

The bare-root approach is by far the easiest but also the least successful. It involves digging up your geraniums, shaking most of the soil from the roots, and hanging the plants upside down in a cool basement or dry crawl space where the temperature hovers at 45 to 50 degrees.

Once a month, soak the roots for an hour or two in warm water. Expect that leaves will probably turn brown, dry up, and fall off. If all goes well, though, stems should remain green. In March, cut each plant back by half or to green, fleshy, solid stems. Pot each plant up and water thoroughly, placing the geraniums in a bright, sunny window. Plants should start budding out, sending out new shoots, and developing into attractive plants that can be set outside in May.

These tips first appeared in Illinois Times Oct. 18 last year. Dave Robson is an extension educator with the Sangamon/Menard unit.

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