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Your vision of window boxes spilling over with geraniums (Pelargonium spp.) can come true if you save your plants this year and start out next spring with established plants. Keep geraniums healthy all winter by cutting back on water, fertilizer, and the plant's foliage.
What to Do This Fall and Winter: Wash off. "Give each plant that you plan on bringing indoors a good washing off to remove any pests," says Lane. As an extra precaution, you may also spray the plant with an insecticidal soap spray
(see "Plant Rx," right).
Acclimate slowly. Moving a sun-loving plant abruptly from a bright outdoor
location to the indoors can shock it into dropping its leaves. Jon Mugglestone, a horticulturist at the United States Botanic Garden, recommends moving plants under a shade tree for a few days and then to a very sunny spot indoors.
Trim down. Cut back the plant's foliage by one-half in mid-September (see the trimmed geranium above). Remove all dead or yellowing leaves.
Lighten up. House your geranium under lights or in a bright indoor location, such as a south-facing window (see "Let There Be Light" on page 55).
Pinch back. Houseplant geraniums tend to become leggy. Encourage bushier plants by pinching new growth back to just above a healthy set of leaves.
Water less. Geraniums have succulent stems—that is, they store water in their stems—so they actually prefer drier conditions. As the days shorten and the weather cools, your geraniums will need less water. Water only when their soil is dry down to your second knuckle. Don't fertilize from October to March, because fertilizing in the off-season encourages leggy, soft foliage that is susceptible to disease.
Don't worry. Plants that spend the winter inside won't necessarily look fantastic, Lane warns. The goal, says Mugglestone, is to get them through the winter healthy so that you can start next season with an established specimen.
What to Do Next Spring: Fertilize lightly. Apply fertilizer in half-dilution from March until May, and then full dilution from May until September, advises Peggy Campbell, of Molbak's Nursery in Woodinville, Washington.
Move out. Suddenly moving your plants outdoors can shock them. So, two weeks before your average last-frost date, begin taking your plants outside to harden off. On the first day, place them in a sheltered, shady spot for two hours and then bring them back inside. Gradually increase the length of time they spend outside and the amount of sun and wind they receive. By the end of the two weeks, you can leave them outside all day.
Plant Rx Cuttings and overwintered plants often fall victim to three tiny insects:
Aphids suck the life out of your plants (literally) by feeding on plant sap. Look for clusters of tiny, pale green insects on the undersides of leaves.
Mealybugs look like tiny cotton tufts clinging to the undersides of your plant's leaves.
Spider mites are tiny reddish orange mites that feed on plant sap and may form a fine webbing on plant leaves and stems.
The solution: Carefully observe your plants. If you notice any problem insects on a plant, take it outside and wash it off with a heavy stream of water. Then spray the entire plant, including the undersides of leaves, with a commercial soap spray such as Safer Soap. Rinse off the soap before bringing the plant back inside. Keep watch and repeat this treatment if the pesky critters return.
