Although poinsettias are typically equated with the holidays, another group of plants to consider are the Thanksgiving and Christmas cacti, according to LSU AgCenter horticulturist Dr. Allen Owings.
Christmas cactus is probably the most popular of the holiday cacti and was a favorite house plant for the holiday season in years past. Although it is not as popular as poinsettias, Owings recommends it for long-term enjoyment.
Christmas cactus is known by the scientific name Schlumbergera bridgesi. Thanksgiving cactus is a related species and is sometimes called crab cactus. Its scientific name is Zygocactus truncatus or Schlumbergera truncatus. Thanksgiving cactus blooms from October to November and has rather flat, glossy green leaves that are distinguished by two prominent teeth (claws) at the growing tip. Flowers are usually scarlet.
Christmas cactus is distinguished from the Thanksgiving cactus by its rounded leaves with blunt tips. Flowers are carmine-red with a purple tinge in the center.
Another holiday cactus that blooms later on in the spring is the Easter cactus. It blooms in March and April and is scientifically classified as either Schlumbergera gaertneri or Rhipsalidopsis gaertneri. Easter cactus has long, flattened joints, dull green leaves with rounded margins and a few bristles at the growing tips. Flowers are a deep scarlet and star-shaped. Also, they are symmetrical, which distinguishes them from the other two holiday cacti.
Owings says many hybrids now are available among all these cacti, featuring different growth habits, foliage characteristics and flower colors previously not seen in older varieties.
Flowering in most of the holiday cactus is regulated by day length and temperature. Christmas and Thanksgiving cacti bloom when given shorter fall days and cool nights. Owings points out that these same conditions cause bract coloration and flowering in poinsettias.
Thanksgiving cactus sets buds as early as mid-September (with major flowering in October and November). Christmas cactus has its buds set by late October or early November (with major flowering around Thanksgiving and continuing through early January). Flower buds of Easter cactus develop more slowly and will not appear until late winter or early spring.
After cacti complete flowering, plants produce new vegetative growth. The new growth supports flower bud development for the next bloom. During this active growth period, the horticulturist says to increase water and fertilizer application. Harden off new growth and increase opportunity for bud development in the fall by reducing irrigation and fertility in mid-August.
Holiday cactus thrives in a well-drained, sterile potting medium that is high in organic matter. Sand may be added to increase the weight of the medium. As plants develop new branches and buds, they often become top-heavy and difficult to handle. A soil pH of 5.5-6.2 is optimum for growth.
Clay pots are great for cactus because they are porous and allow the soil to dry out some between waterings. Use a wide, short pot to assist in balancing out any top-heavy growth that the cactus produces.
Fertilize until flower buds appear. Owings recommends a good soluble fertilizer, such as 20-20-20). But he cautions not to overwater. "This is a major problem on cacti," Owings says.
Maintain temperatures of 70 degrees F to 80 degrees F for ideal growth. A cactus will tolerate 90-degree F to100-degree F temperatures, but vegetative growth may be reduced. Avoid direct sun exposure during the late spring and summer.
For related topics, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site: www.lsuagcenter.com. Additional yard and garden topics are available from an extension agent in your parish LSU AgCenter office.