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Reblooming Poinsettias and Christmas Cactus


The colorful parts of the poinsettia are the bracts and the knobby yellow growths that appear in the center are the flowers. Photo courtesy of MelindaMyers.com.

The colorful parts of the poinsettia are the bracts and the knobby yellow growths that appear in the center are the flowers. Photo courtesy of MelindaMyers.com.

Gardeners like a challenge and the sense of accomplishment when trying something new. Forcing poinsettias and Christmas cactus to rebloom provides such an opportunity.

These plants need 14 hours of uninterrupted darkness each night to set flowers for the winter holidays. Starting between late September and October 1st, cover or move your plants into a dark location each night. Shield them from any outdoor, street or reading lights that can delay or prevent flowering.

Uncover or move your plants back to a brightly lit location each morning. Growing the plants in a cooler location, especially at night, and keeping the soil slightly drier will help stimulate bloom. Some experts believe this is all that is needed to rebloom Christmas cactus. A combination of the two treatments seems to give the best results.

The colorful parts of the poinsettia are the bracts, often called the flowers. These are leaves that turn color after the dark treatment. The true poinsettia flower is the knobby yellow growth that appears in the center of the colorful bracts at the tip of stem.

Continue the dark treatment until the poinsettia bracts are fully colored or your Christmas cactus is covered with well-developed buds. Move the flowering plants to a cool, bright location free of hot and cold drafts. Continue to water thoroughly and often enough to keep the soil slightly moist while the plants are flowering. This is especially important to prevent bud and flower drop on Christmas cactus.

Consistently providing the required dark period is key to having flowers for the holidays. Each missed or interrupted 14-hour night delays blooming by one day. There is no need to give up after a couple of interrupted nights. Just enjoy the event when your poinsettia does bloom. Their colorful bracts are sure to brighten any winter day.

If your poinsettia fails to flower, you can still enjoy your plant this winter. Just add some faux poinsettia blooms, berry sprays or other floral décor. No one needs to know this wasn’t the plan all along.

Don’t be surprised if flowers appear on your Christmas cactus at Thanksgiving. Although sold as a Christmas cactus, it may truly be a Thanksgiving cactus or a hybrid of the two. The true Christmas cactus has small segments with smooth edges and blooms later than the Thanksgiving cactus with toothed or jagged segments.

Fortunately, the Christmas and Thanksgiving cactus’ growing requirements and care are basically the same. The plants will do fine; they just bloom during different holidays. Both are native to the tropical rain forests, not the desert, as their common name implies. They both prefer bright light, high humidity, and a thorough watering when the top few inches of soil begin to dry when they are actively growing.

Enjoy the experience as well as the results. As with any gardening endeavor, the fun is in trying something new.

Melinda Myers has written more than 20 gardening books, including the recently released “Midwest Gardener’s Handbook, 2nd Edition” and “Small Space Gardening.” She hosts The Great Courses’ “How to Grow Anything” instant video and DVD series and the nationally syndicated Melinda’s Garden Moment TV & radio program. Myers is a columnist and contributing editor for Birds & Blooms magazine and her website is www.MelindaMyers.com.

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