To get more mileage out of certain plants, grow them in the garden during the summer and indoors during the winter.  The best way to do this is to root cuttings that you clip in midsummer.  You'll not only have plants to enjoy indoors during cold months, you'll have sizable starts for next spring.  The easiest plants to manage in this dual role are coleus, wax begonia, geranium, and impatiens.  Take only as many cuttings as you can handle indoors.

Cut about four inches of stem just below a leaf axil.  Remove the lower leaves, and insert the cutting into a peat and perlite mix or coarse sand.  It is possible to root cuttings in water, but a later transfer to the growing medium might be tricky, because roots will be delicate.

After the cuttings are stuck in the rooting medium, water well, and place the container in a tightly closed plastic bag.  Place in good light but not direct sun.  In about ten days, check for rooting by gently pulling on the cutting.  When you feel resistance, the cutting is rooted.  Pot it up, using a rich, porous potting soil in a three-inch pot.  Move to bright light, and water whenever the soil surface dries.

Taking cuttings in midsummer also benefits the plant.  The snipping will reshape overgrown or sprawling plants and will ensure a fall flush of bloom for many plants.

Although it is possible to dig plants out of the garden and bring them inside for the winter, you'll have better luck carrying them over by cuttings.  Plants dug from the garden are often leggy, one-sided, or in a soil riddled with insects and disease.  (The pests then often will spread to your pampered houseplants.)  Leaves will fall when the annuals first move in, leaving behind an even leggier plant.