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Elisabeth C. Miller Library

Keyword: Schlumbergera

encouraging Christmas cactus to bloom

I have a Christmas cactus that is very healthy and blossomed profusely last November. I attempted to duplicate the same environment that the cactus had a year ago, but that wasn’t possible, and it didn’t produce a single blossom. The foliage is glossy with health, but I don’t water the plant for a couple of months in the fall to stress it a bit to encourage blossoms.

I put the cactus in our dark, cool garage for the month of October just as I did last year. When I returned the cactus back upstairs in our house to its usual south window spot and watered it, it gave no blossoms this year. Why?

I’ve looked online and in books for info on encouraging bloom, but I haven’t come across much about Christmas cactus. The cactus gets direct southern light all year except for the month when it is in the garage, which has only a north window. Is lighting the problem? The garage is about 65 degrees F, same as last year, so I’m thinking the temperature isn’t part of the problem, or is it?

 

There may be a combination of factors involved in the lack of flowers on your plant. If it is a young plant, it may have needed repotting. It may not have been in the dark, cool environment quite long enough or soon enough. According to The Complete Houseplant Survival Manual by Barbara Pleasant (Storey Publishing, 2005), the ideal conditions for Christmas cactus (Schlumbergera hybrids) are as follows:

  • Bright light from late spring to fall, and moderate light from late winter to early spring
  • 65 to 80 degrees from late spring to late summer, and 50 to 65 degrees during fall and winter
  • Balanced fertilizer every 2 weeks from spring through summer, and monthly in fall and winter
  • From spring through fall, keep soil lightly moist but in winter, it should nearly dry out before watering sparingly
  • Repot young plants each summer; older plants can be repotted every 2 to 3 years
  • Plants tend to have a lifespan of 5 to 6 years, but you can propagate them from stem cuttings

Clemson University Extension has additional information on growing Schlumbergera. Here is an excerpt:
“The secret of good flower production involves temperature and dark (photoperiod) control. To flower, plants need bright light; night temperatures between 55-65; long nights–13 hours or more of continuous darkness each day is required before flowering will occur. Long nights should be started about the middle of September and continued for 8 weeks.”

 

controlling whiteflies and recycling grass clippings

I have whiteflies on my orchid Christmas Cactus. How can I get rid of them? I also would like to know if grass clippings are good to fertilize raspberries.

Christmas cactus, or Schlumbergera bridgesii, does occasionally have problems with insects. Whitefly nymphs and adults cause damage by sucking plant juices, and their feeding can weaken a plant. They also secrete a sticky substance called honeydew, which may then harbor sooty mold. For indoor plants affected by this insect, you might try gently washing the leaves. Rodale’s Encyclopedia of Indoor Gardening, edited by Anne Halpin (1980) says that adults are easy to wipe up when it is colder indoors, and the young are usually on the undersides of leaves and may be wiped off with a sponge. Many whiteflies are now resistant to insecticides, and so it is best to start with plain water or soap and water. The book Indoor Gardening the Organic Way by Julie Bawden-Davis (Taylor, 2006) lists sticky traps, insecticidal soap, alcohol spray, oils, and pyrethrin as potential controls. There are products containing Neem oil which could help, if plain water or soapy water don’t control the problem.
Clemson University Extension has some helpful information on general care of this plant.

As for using grass clippings as fertilizer, as long as the grass was not treated with weed-and-feed or other pesticides, it should be a good source of nutrients. Also, avoid using grass which has already gone to seed. Mulch It! by Stu Campbell (Storey Books, 2001) advises not to spread the clippings too thickly, and to let them dry out a bit before using. Here is a link to Virginia Cooperative Extension’s page on recycling grass clippings.

Taylor’s Guide to Fruits and Berries edited by Roger Holmes (Taylor, 1996) says that “reasonably good soil enriched with an inch or two of good compost or a moderate dose of balanced fertilizer each year should provide sufficient nutrients for your plants to thrive. Berry lovers sometimes provide regular doses of foliar fertilizers to give their plants a boost. Absorbed by the leaves in liquid form, seaweed, fish emulsion, and similar organic materials in balanced formulations provide a broad spectrum of nutrients.”