Extend the Life of Your Summer Annuals

By Joanne K., Pitt County EMGV
Coleus displays  in many home and public container gardens around the area have been spectacular this year. Perhaps you have a favorite coleus or another summer annual that you don't want to lose when the frost comes.

Coleus Green (Coleus scutellarioides) in late summer.
Photo by Joanne K.

As summer winds down, many annuals have luxuriant growth from which cuttings can be taken to propagate over the winter to enjoy in your garden next spring. Propagating cuttings is a fun way to extend your gardening season.

Following are two easy propagation methods using stem cuttings.

i) Angel Wing Begonia (Begonia coccinea) leaf about
    to be cut. 
ii) Angel Wing Begonia leaf cut in half horizontally.
Photos by Dick W.

1. Use a pot with good drainage and fill it with a commercial seed starting mix or perlite.

Select a healthy stem or a large leaf with a stem.

Cut a 4"-6" long stem with several leaves between nodes. When cutting a single large leaf such as an angel wing begonia, cut it in half horizontally to encourage root development.

Remove flowers and any leaves from the bottom half of the stem, moisten it, and then dip it in rooting hormone (available at garden centers). The stem of the single leaf should also be dipped in the rooting hormone.

Make a hole in the moist commercial seed starting mix or perlite and place the stem or the large leaf in it. The stem should have one node below the soil line for root growth.

Several cuttings can be placed in a single container. It's a good idea to take more than one cutting to ensure successful rooting.

Cover the container with a bottomless milk jug or a clear plastic bag to maintain high humidity. Be careful to keep the leaves clear of the covering to prevent mold from developing.

Keep away from direct sunlight and water lightly if needed to keep the mixture moist but not soggy.

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2. Rooting in water (begonia, coleus, geranium, and impatiens)

Take a 4"-6" stem cutting and place it in a jar of water, removing any leaves below the water line.

Change the water every three days to give new oxygen to the plant. Keep the container out of direct sunlight.

What to do once the cutting forms roots
How will you know it's time?
Most cuttings root in 4 to 6 weeks. A gentle tug on the stem cutting will have some resistance.

You may also see new growth at the base of the leaf cutting. In water, the roots are visible.

You are ready to pot it up in a planter with regular potting soil. Place each cutting in a separate planter and water. Don't water again until the top inch of soil is dry.

Beefsteak Begonia (Begonia erythrophylla) leaf cutting showing new leaf at base.
Photo by Joanne K.

Place the planter in a properly lit place for the type of plant you have. Use a 10-10-10 fertilizer when needed according to package directions.

Six Beefsteak Begonia (Begonia erythrophylla) leaf cuttings rooting in one container.
Photo by Joanne K.

The following annuals respond well to home propagation, but feel free to experiment with propagating your other container and bedding plants. You may be surprised how easy it is to do.

Floss flower, Ageratum; Wax begonia, Begonia ? semperflorens-cultorum; Dragon wing begonia, Begonia; Angel wing begonia, Begonia coccinea; Coleus, Coleus scutellarioides; Geranium, Pelargonium; Polka dot plant, Hypoestes; Impatiens, Impatiens walleriana; Persian shield, Strobilanthes dyerianus; Petunia, Petunia; Sweet Potato Vine, Ipomoea batatas; Verbena, Verbena; Vinca, Catharanthus roseus.

Coleus (Coleus scutellarioides) stem cutting rooted in water.
Photo by Joanne K.

For an excellent series of plant propagation photos and instructions go to the following Missouri Botanical Garden site:

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/propagating-plants-by-cuttings#:~:text=Some plants will root in,rot if kept too wet.