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.

Zonal Geranium
[Winter Houseplant]

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.

Plants That Make the Cut and In-House Favorites
Plants That Make the Cut
Begonia spp.
Chrysanthemum spp.
Coleus (Solenostemon scutellarioides)
Dahlia spp.
Impatiens spp.
Lantana spp.
Ornamental sweet potato (Ipomoea batatas)

Make your own inexpensive cloche by draping a plastic bag over chopsticks.

Premoistening the medium prevents it from floating away when you water.

Prevent disease by cleaning the knife's blade with alcohol after each cut.

In-House Favorites
These plants also don't mind wintering over on your windowsill:

Coleus (Solenostemon scutellarioides)
Flowering maple (Abutilon spp.)
Heliotrope (Heliotropium spp.)
Hibiscus spp.
Lantana spp.
Rex begonia (Begonia rex)

You can root the trimmings from your geranium, but first allow the cut ends to dry for 24 hours. This allows the wounded ends to form scabs, which prevent the cuttings from rotting once they're planted.