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Gardeners, listen up. You need not stand by each fall while Jack Frost kills off your favorite tender plants one by one. You can rescue your plants from certain death by bringing them in for the winter. Coleus, begonias, and even heliotropes don't mind taking a holiday as houseplants. And once your plants are indoors, it's easy to make more with cuttings. On the following pages, we've laid out a strategy designed to keep your plants healthy through the winter so that you can start spring a step ahead.
Coleus
[Cuttings]
Want to dip your toe into the world of plant propagation? Making cuttings of coleus (Solenostemon scutellarioides) is an easy way to get started, because they root well and grow quickly.
What to Do This Fall and Winter: Prepare the rooting medium. Roots push easily through a one-to-one mixture of perlite and soilless potting medium. "Make sure the medium is sterile," says David Nelson, a gardener at the United States Botanic Garden. To ensure sterility, use new bags of perlite and soilless mix, and disinfect all planting trays and pots with a 10 percent bleach solution. Then premoisten the medium and fill the planting containers with it. (Choose containers with drainage.)
Pick a stem. Take cuttings earlier rather than later, says Dayna Lane, an organic gardener and plant records technician at the United States Botanic Garden. "If you wait too late in the growing season, the cuttings often won't take off." Choose a nonflowering, thicker stem with healthy leaves and new growth, recommends Bill Lamack, grounds and nursery manager at Bowman's Hill Wildflower Preserve in Pennsylvania.
Make the cut. A cutting needs to be 3 to 4 inches long and include three to six nodes—the swollen areas where leaves adjoin the stem. Cut just below a node. Remove leaves from the bottom 1 to 11?2 inches of the stem, because they will rot if buried in the soil medium. Be sure to use a sharp knife when making cuttings and removing leaves, Lamack says. Using scissors or pinching with your fingers crushes the plant tissue, which makes it more susceptible to disease.
Plant the cutting. Using a chopstick, make a hole in the medium that is as deep as the leafless end of the cutting. Hold the cutting by its leaves and insert it into the prepared hole. Gently firm the medium around the cutting's stem with the chopstick. Label each cutting and place the tray in a bright window or under lights (see "Let There Be Light," below).
Keep it humid. "When you make a cutting, you remove the plant from its roots," Lamack says. "It's important to increase humidity around the cutting so it doesn't dry up and die." Keep things humid by placing a cloche over the tray. If the cuttings begin to wilt, spray them with a fine mist. Keep the rooting medium evenly moist, but not soggy.
Put down roots. Cuttings should root in two to four weeks. Placing the tray on a heat mat speeds root development. Check for rooting by gently tugging on the cutting. If your tug meets with resistance, roots have most likely started to form. New growth is a sure sign that roots are developing. Transplant each cutting into its own pot (filled with soilless potting mix) when it develops roots that are a few inches long. Place a cloche over the transplanted cuttings.
Pinch back new growth. Keep your plants compact and bushy by occasionally pinching back new growth to a set of healthy leaves.
What to Do Next Spring: Fertilize lightly. In March, or when the plant begins actively growing, fertilize your rooted cuttings with a diluted solution of fish emulsion or liquid kelp.
Harden plants off. Harden off your cuttings before you move them back outside permanently (see "Move Out" under Zonal Geranium), and be sure to plant only after the last frost.
Let There Be Light Plants need sunlight for photosynthesis—the process that uses light energy to convert carbon dioxide and water into essential sugars and starches (plant food). Photosynthesis slows down in plants that don't receive enough light, so they grow more slowly and produce pale foliage and few or no flowers. Plant stems often elongate in search of light, resulting in weak, leggy growth. Place overwintering plants and rooted cuttings in as much natural light as possible. If the plants show symptoms of inadequate light, set them on a table under a fluorescent shop light for 12 to 18 hours per day for the remainder of the winter.
