Allen D. Owings | 12/18/2007 9:20:30 PM
Although poinsettias are typically associated with the holidays, another group of plants to consider are the Thanksgiving and Christmas cactuses. LSU AgCenter horticulturist Dr. Allen Owings recommends them for long-term enjoyment.
Christmas cactus is probably the most popular of the holiday cactuses and was a favorite house plant for the season in previous years.
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 edges 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 cactuses.
Owings says many hybrids are available that feature different growth habits, foliage characteristics and flower colors not seen in older varieties.
Flowering in most of the holiday cactuses is regulated by day length and temperature. Christmas and Thanksgiving cactuses bloom because of shorter fall days and cool nights. 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 bud 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 cactuses finish flowering, they produce new vegetative growth. The new growth helps buds develop for the next bloom cycle. Owings advises to water and fertilizer more during this active growth period.
In mid-August, water and fertilize less to harden off the new growth and increase opportunity for bud development in the fall.
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. A soil pH of 5.5-6.2 is optimal for growth. Clay pots are great for cactus because they are porous and allow the soil to dry out somewhat between waterings.
As plants develop new branches and buds, they often become top-heavy and difficult to handle. 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. Be careful not to overwater. This is a major problem. Maintain temperatures between 70 and 80 degrees for ideal growth. A cactus will tolerate 90-100 degrees, but it will grow slower. Avoid direct sun exposure during the late spring and summer.
For related ornamental plant information, click on the Lawn and Garden link at the LSU AgCenter Web site, www.lsuagcenter.com. Also, contact the county agent in your local parish LSU AgCenter office.