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Sad at the thought that your cheery geraniums will
soon fall victim to the dropping temperatures of autumn? It’s
possible to beat the frost and save the plants by taking them inside for
the winter.
“As soon as we get freezing temperatures, most
unprotected annual geraniums will turn a mushy green and die,” says
David Robson, a horticulture educator with the University of Illinois
Extension. “However, it’s possible to take those geraniums
before they get nipped by a hard frost and overwinter them indoors. Gardeners have several alternatives, including
potting the plants, taking cuttings from them, or storing the plants as
bare-root specimens. It is important to make sure that the plants are
vigorous, healthy, and insect- and disease-free. White flies, aphids, and
mealybugs, which hide on the plants, will spread indoors, where predators
can’t keep them in check. “Check the soil to avoid bringing in other
hitchhikers,” Robson says. “Some gardeners will always repot
the geranium in fresh houseplant soil. That might be a little unnecessary,
though it practically guarantees no soilborne 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. Use potting soil
instead of garden soil to avoid a soggy, heavy soil indoors. 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 cutting approach 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,”
Robson says. “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, Robson says. 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,” he says. “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.”
For information about the University of Illinois
Extension Sangamon-Menard Unit, go to www.extension.uiuc.edu/sangamon.
This article appears in Oct 11-17, 2007.
