Geraniums, impatiens can be overwintered successfully

Question: This fall, I dug up and potted all of my impatiens, geraniums and begonias. So far, they are doing well and still in bloom. How can I best care for them through the winter• I'd like to replant them outside next spring. Right now, I have them in a large window, but it gets very little sun. Should I give them some extra light?

Answer: It's quite easy to overwinter geraniums and impatiens indoors as long as you provide them with some basic needs. They should receive ample light; otherwise they will get leggy and pale. Because your window isn't very bright, I would recommend hanging a fluorescent shop light from hooks in the ceiling above them. Your primary goal is not to produce blooms, so you don't need to purchase special light bulbs. Just use fluorescent tubes. Keep the lights about 5 inches above the plant tops and move the lights higher if the plant grows. You'll want to have them on for 12 hours to 15 hours per day. Of course, you could invest in an "official" grow light (available online ), which will encourage blooms.

Another good tip is to be careful to avoid over-watering. Geraniums and impatiens are prone to fungal diseases like botrytis if they are watered too often or if the foliage is frequently wet. Be sure the container has good drainage, and do not allow water to sit in the saucer beneath.

There is no need to fertilize through the winter, because you don't want to encourage too much active growth. But do begin to use a diluted kelp emulsion fertilizer when April arrives. You can do this every two to three weeks until the plants can be moved outdoors.

Pinching the plants back might be another necessity once or twice during the next few months. In order to keep the plants compact and bushy, use sharp, clean scissors to remove the terminal two inches from each stem. This will encourage a well-branched plant that is less likely to become leggy and top heavy.

As for the begonias, I don't know which type you have. If they are wax begonias, you'll have a challenging time overwintering them, and it usually isn't worth the effort. If they are dragon-wing or angel-wing begonias, you can follow the directions above. If they are tuberous begonias, your best bet is to dig up the fleshy tuber, cut off all the foliage, brush off the soil, let them sit for a week in a cool, dry place, and then store the tubers in a cardboard box filled with peat moss in the garage. Replant the tubers into the garden in late May.

Horticulturist Jessica Walliser, co-author of the book "Grow Organic," can be heard from 7-8 a.m. Sundays on KDKA Radio's "The Organic Gardeners." You can also find her teaching at Phipps Conservatory and Botanical Gardens, where she has been a faculty member for more than 12 years.