Most varieties of the so-called Christmas cactus are really examples of the Thanksgiving cactus.

While there is a type of cactus named the Christmas cactus, the Thanksgiving species has by far the most hybrids and is more prominent during the Yuletide season.

The kind you see most often at Christmas has three to four pairs of saw-toothed projections resembling crab claws on the leaves, and that’s the Thanksgiving or crab cactus. The leaves of the true Christmas cactus, in contrast, are rounded with no saw-toothed edges.

Despite their differences in leaf shape, the two types have quite similar flowers. The Thanksgiving cactus flower comes in many colors from white, to magenta, to red. Christmas cactus blossoms are mainly cherry red.

There’s also a third species: the Easter cactus, which is much different from the other two. The leaf is thickened or even triangular with hairy projections at the tips of the leaves. The Easter cactus has many branches. Flowers come in many colors, ranging from pink, to red, to violet.

The Thanksgiving cactus initiates flower buds sooner and produces flowers earlier than the Christmas species. In some tests of the two species at the same age, flower buds on the Thanksgiving type were visible Sept. 20, while buds on the Christmas cactus were not visible until Oct. 24.

After the normal Christmas blooming season, both species can flower again at or near Easter. To succeed with this, night temperature should be no higher than 60 degrees Fahrenheit. Research with the two common species shows they respond best to eight hours of light daily and 60 degree Fahrenheit for flowering. If flower buds start to drop, the temperature may be too high or the light intensity too low. Christmas cacti seldom flower well at temperatures above 75 degrees Fahrenheit.

New leaves will develop in the spring. At that time, Christmas cacti can be replanted. Use a rich, acid-type soil of one part leaf mold, one part sharp sand, and a handful of bonemeal in an eight-inch pot. The plants are rarely bothered by insects or disease and enjoy summers outdoors under a tree where they can get light shade.

Next year you should leave them outdoors as long as possible in the fall. If you bring the plants inside before Oct. 1, place them in a cool, light area of the basement. Bring them to a sunny window as soon as buds start to show.

Easter cacti are not as dependent upon day length for flowering as the Thanksgiving and Christmas species. Although they will set buds naturally from January to March, they will bear flowers under cool temperatures at other times of the year.

“Growing Green” is contributed by Lehigh County Extension Office Staff and Master Gardeners. Information: Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-746-1970.