One of the plants mentioned last month as a nice gift for the holidays was the Christmas Cactus. One of the most asked questions about the Christmas Cactus is, “why doesn’t my Christmas Cactus bloom at Christmas?” The fact is that there are several species of holiday cacti; each of them has certain requirements for blooming and they bloom at various times depending on those conditions. Cacti are succulents of which there are over 2000 species that grow all across the Americas from the Arctic Circle to the Andes mountains of Chile.
Most cacti that are grown in Minnesota are grown indoors as houseplants and probably the most popular of these are the holiday cacti. Holiday cacti can be very long-lived. It is possible for these plants to live over 100 years, passed down from generation to generation.
Christmas Cactus (Schulumberga bridgesii), Thanksgiving Cactus (Shulumberga truncata) and Easter Cactus (Ripsalidopsis gaertneri) are true cacti, but they do not have the same requirements of the desert cacti that we see in southwestern United States. Holiday cacti are epiphytes which means they cling to or are supported by trees in the forest, but they are not parasitic (feeding off the host plant).
Bromeliads and orchids are other examples of epiphytes. They are native to tropical rain forests and require high humidity, bright filtered light and relatively moist soil.
The sharp teeth in the leaf margin distinguish the Christmas and Thanksgiving Cacti, while the leaf of the Easter Cactus has smooth waves along the edges. Holiday cacti bloom at different times of the year but not by the calendar. Rather they require short days and cool nights.
Holiday cacti should be potted in standard cactus soil mix, or you can make your own with two parts potting soil and one part sand. Prior to and during blooming they should be watered thoroughly but allowed to dry out between waterings.
In the fall (or 6-8 weeks before you want them to bloom) the plants should be placed in a bright location; the brighter the sunlight the more blooms will be produced. Nighttime temperatures should range from 55º -65º and daytime temperatures 5º- 10º higher. If nighttime temperatures are kept at 55º then the plant should bloom in 5-6 weeks. If nighttime temperatures are 60º – 65º, then the plant will require 12 hours of total darkness per night in order to bloom. You can move them to the basement or a dark closet, or cover them with a dark cloth to attain this. Just remember to return them to the bright sunlight during the day. If nighttime temperatures are any higher than 65º then it is unlikely that the plants will bloom at all. The plants are very sensitive to environmental changes during bud formation. Drafts, sudden changes in temperature or humidity, or even the direction of sunlight they receive can result in bud drop. Avoid moving or disturbing the plant from the time you see buds until the plant is in full bloom.
After your cactus blooms prune out several sections with a sharp knife. This will cause the plant to branch out resulting in a fuller plant with more blossoms next year. Water less frequently and refrain from fertilizing until the late spring or early summer when the plant begins to actively grow again. Then you can increase the watering and fertilize with a diluted houseplant fertilizer.
Plants can be moved outdoors in the summer but should be kept in a shady or semi-shady spot. Avoid hot direct sunlight –if exposed to too much sunlight the leaves will turn reddish. With a minimum of care, but good timing of cool nights and bright days, you should be rewarded with a blooming plant for the holiday – whichever one you want.
Happy New Year!
“Shed no tear – O shed no tear! The flower will bloom another year
Weep no more – O weep no more! Young buds sleep in the roots white core.” –John Keats.