The orchid family (Orchidaceae) thrives in U.S. Department of Agriculture plant hardiness zones 3 through 12 depending on the species. In general, you cannot replant a cut orchid stem to make a new plant. Instead, orchids are propagated by dividing pseudobulbs and rhizomes or planting offshoots, also known as "keikis."
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About the Orchid Family
Of the 20,000 to 30,000 orchid species, approximately 70 percent are epiphytic plants. They grow on other plants, like rainforest trees, but are not parasites. Among the many epiphytic orchids grown as houseplants are the Cattleya species, hardy in USDA zones 10 through 12, and the Dendrobium and Oncidium species, hardy in USDA zones 9 through 12.
Moth orchids (Phalaenopsis spp.), hardy in USDA zones 10 through 12, are the easy-care epiphytic orchids found in garden centers and grocery stores. These orchids thrive in bright filtered light and temperatures between 60 and 85 degrees Fahrenheit. The delicately arching stems feature multiple blossoms that can last for months.
Terrestrial orchids like the lady slippers (Cypripedium spp.) thrive in USDA zones 3 through 8. Unlike their tropical cousins, lady slippers grow into large clumps in rich, moist, well-drained soil in light or dappled shade. These hardy orchids may be propagated by dividing the rhizomes or from seeds, but the seeds need the help of a soil fungus (Rhizoctonia genus) to germinate.
Sterilize Cutting Tools
Orchids are susceptible to viruses and other plant diseases. Sterilize your cutting tools by dipping the blades in rubbing alcohol or full-strength Lysol or Pine-Sol. Allow the blades to air dry. You can also wipe the blades with a rag dipped in the sterilizing solution.
Always wear gloves and safety glasses when using cutting tools. Add a mask when working with potting soils, compost, bark, fertilizer and other products to protect your lungs.
Propagate From an Orchid Stem
Keikis may develop on the flower spikes of moth orchids as well as Cattleyas and Dendrobiums. When these little plantlets appear, allow them to grow until the roots are 1 to 3 inches long, and it has two or more leaves. Cut the stem with a sharp knife or pruner 1 inch above and 1 to 2 inches below the keiki. Plant in fresh orchid mix using the stem to anchor the keiki or add a stake to keep it stable in the pot.
Keep the new orchid plant in bright, filtered light and mist regularly. Water once or twice a week and fertilize with one-half to one-quarter strength orchid fertilizer. A keiki may take three years or more to mature and develop flower spikes.
Divide Orchid Plants
Orchids that grow from rhizomes or rhizomatous roots, such as Cattleyas, can be divided like any other houseplant in spring. Water thoroughly and then slide the orchid from its pot. Rinse the potting mix from the roots and then divide the roots so each section has roots and at least one pseudobulb or stem. Dust the cut ends with a fungicide and repot in fresh orchard mix.
Replant a Cut Orchid Stem
There's an exception to every rule, and a few of the Dendrobiums are "it" when it comes to rooting from cuttings. The long stems, or pseudobulbs, can be cut from a parent plant, like the Noble Dendrobium (Dendrobium nobile). Cut each stem into sections containing three to four nodes each.
Fill a tray with moist peat moss and lay the sections horizontally on top. Cover the tray with plastic wrap and set it on a seedling heat mat to keep the cuttings at a consistent temperature of 75 to 85 degrees Fahrenheit. Mist regularly with water to keep the cut stems moist. Fertilize with diluted, one-quarter-strength liquid nitrogen fertilizer biweekly and similarly diluted 6-6-8 liquid fertilizer on the alternate weeks until roots and leaves appear. Replant in small flowerpots and place them in a warm, brightly lit location.
- Brooklyn Botanic Garden: Orchids and How They Grow
- Missouri Botanical Garden: Cattleya (Group)
- Missouri Botanical Garden: Dendrobium (Group)
- Missouri Botanical Garden: Oncidium (Group)
- American Orchid Society: What Is Growing on the Flower Stem?
- St. Augustine Orchid Society: Propagating Orchids Vegetatively
Ruth de Jauregui is the author of 50 Fabulous Tomatoes for Your Garden. She writes numerous home and garden articles for a variety of online publications. She got her start as a book and cover designer in San Francisco for William (Bill) Yenne at American Graphic Systems. In addition to designing books, she wrote her first book, Ghost Towns. With several nonfiction books under her belt, de Jauregui recently published her first novel, Bitter.