This is the time of year when I make yet another stab at bringing plants in from the garden for the winter. I always have great success in getting new plants started, but nurturing them through the winter is the real challenge.
I've had excellent luck with geranium, rosemary, thyme and tarragon cuttings (I care more about having herbs than flowers in my house during the winter). I'm told that impatiens is easy to root, and this year I'll also try to propagate my lantana.
The cuttings should be good, healthy stock from the top of the plant. Many plants -- rosemary, tarragon, a mature geranium and lantana, for instance -- have very woody lower stalks that don't lend themselves well to rooting. You won't have this problem with impatiens, but it's still a good idea to clip an active, growing shoot to root. The only exception is thyme, which can be pulled right off the ground where it spreads, sending out many small roots from new stalks that creep along the ground. Cuttings should be about six inches long.
Although many books recommend using rooting powder (available at any garden center) to start cuttings, I've had good luck with simply putting cuttings in a wide-mouth glass jar of water. Within a few days, or a couple of weeks, small white roots will sprout from the bottom of the stalks. Once a good number of long new roots have developed, I simply plant the shoots in good garden soil in clean pots. While there may be some risk of transmitting garden diseases or fungi via garden soil, I've never found this to be a problem. If you're worried, buy some bagged garden soil and add a little sand or vermiculite to lighten it up and hold in moisture.
Thyme that has already rooted in the garden as it spreads can go directly into a pot of garden soil, as long as you keep that soil moist until the new plant has had a good chance to reestablish itself.
Preparing old clay and plastic pots for new plants is important: Wash them in a water-bleach solution or run them through the dishwasher before you put in new plants. There's a greater chance of disease and fungus transmission from used pots than from garden soil that's exposed to cleansing sunlight all the time.
Keep all newly planted shoots evenly moist and watch for healthy new growth. Then treat your potted plants as you would any other house plant, watering and misting as needed, and giving them plenty of light.
NOTABLE NARCISSUS: Speaking of bringing in garden plants for the winter, one lively way of brightening a kitchen window is with fragrant white narcissus. Buy some bulbs now and place them in a shallow bowl or pan of water on a two-inch layer of clean pebbles, available by the bag at your garden center. I like to crowd them so they're almost touching. I never put fewer than three bulbs in a dish, since they look best when they're clustered. Keep the water level up so that the bulb bottoms are always submerged. Some garden books insist you should refrigerate narcissus bulbs for several weeks -- supposedly to simulate winter -- before starting them. I've never done this and I've never had a bit of trouble growing handsome narcissus on my window sills. It's a good idea to provide some sort of support for the narcissus as they grow since they don't have a lot of strength in their stalks and will fall over when loaded with blooms. Small plastic trellises, available at garden centers, do well, and they set off the green foliage nicely. Tie the stalks loosely onto the trellis. In his "Victory Garden" book, James Crockett suggests setting out narcissus bulbs (you can hardly call this planting) every couple of weeks for continuous blooms all winter. It's about two months from the time you put the bulbs in their bed of water and pebbles to blooming, so if you get some onto your windowsill this weekend, you should have something pretty showy by Thanksgiving.