How Do I Grow & Propagate Christmas Cactus
1. Take at least a 3 or 4 stem segment and twist it off at the joint. Some people do take sharp scissors and cut right at the joint - you decide on the method you'd like to use.
2. Allow cuttings to dry a minimum of 24 hours so they seal over.
3. Using 1/2 peat moss and 1/2 perlite soil mix, moisten to just moist - not wet. Plant the cutting half the depth of the first segment in the soil mix.
4. Set in a bright window or bright area outside. Mist it to keep soil from drying out completely. Don't water.
5. The cutting will wilt. Don't be alarmed. This is normal. When it starts to come back to life again - roots should be growing at this time. Any new growth on the cutting is also a sign that your cuttings is taking root.
6. When you see the above signs - you can water normally which means when the soil is dry 1" down -- water until water runs out bottom of container -- then pour off any excess water.
7. Once the cutting has grown one new segment you can start fertilizing until October 1st. Now it's time for blooms!
8. Prepare for blooming - Leave outside to get natural cooling temps at night and natural hours of daylight. If your plant is inside - keep it cool and give it light equivalent to outside daylight.
9. If you are lucky, you will get blooms the first year around Thanksgiving or Christmas. If you root early in the year, this is very possible.
10. After blooming, the plant should rest until March. Watering should be decreased - water when 2" - 3" of depth is dry before re-watering as stated above. Don't let your plant dry out completely. Do not fertilize during this dormant period.
Here is some more info on Christmas & Thanksgiving Cactus Written by: Gardenweb member grant_in_arizona
Despite what you may read in articles by newspaper and magazine columnists (who either don't live in Arizona, or who live here but don't grow Christmas cacti), Christmas cactus and Thanksgiving cactus (genus Schlumbergera) are actually quite easy to grow successfully in the desert southwest, and in Arizona in particular.
Cool, long nights are what trigger blooms in Schlumbergera plants, so the easiest way to encourage bloom is to grow them in pots, in the shade (some morning sun is okay, but not more than an hour or so) and the naturally long, cool nights of autumn will trigger bloom production just in time for the holidays.
Christmas, and Thanksgiving cacti are not desert cacti, but are from tropical jungles, so they appreciate more water than our native SW desert cacti. Water them when their soil is lightly dryperhaps every ten days outside in winter and once a week or so in summer. Give them a thorough drink and then let their soil dry out before the next watering; just keep in mind they are not from desert regions so they cannot tolerate bone dry soil for very long (though they will not tolerate constantly moist soil either).
Being from the tropics, Schlumbergera cacti are absolutely *not* frost tolerant, so while they can take quite chilly nights without any problems, they will not survive a frost, so bring them indoors when frost threatens. In warm winter areas of Arizona, that means you can grow them outside practically year round, but bring them indoors if there is a frost warning in your area. In cold-winter areas of Arizona, just grow your plants outside until frost threatens, and then gradually bring them indoors.by then the chilly long nights will have triggered flower bud production.
Even in frost-free gardens, it can be nice to bring the plants indoors to enjoy their blooms up close and then place them outside again when flowering is finished. Just make sure whenever moving any plants from indoors to out, or vice versa, that you do so over a period of several days so that the plant doesn't go into shock.
Repotting Christmas and Thanksgiving cacti can be done any time they are not forming buds or blooming, so generally repot them in late winter/early spring. They do flower best when crowded in their pots, and this also reduces chances of rot, so repot only when absolutely necessary, perhaps every three years, or even less for very large plants. Any regular potting soil will work fine, although some people prefer to add about 25% by volume of coarse builder's sand (also known as "play sand" or "sandbox sand") available from any large garden center or hardware store.
Fertilizing Schlumbergera is easy: just use any regular house plant, or tomato plant, water-soluble fertilizer once a month from spring through autumn. If mineral deposits or residue from fertilizers or hard water form white spots on the leaves of your plant, just use a paper towel or cotton ball soaked with distilled white vinegar to rub off the spots. I do this just a few times a year for cosmetic purposes. It's always best to "test" your vinegar on your plant by wiping just a segment or two first and then waiting a week to make sure your plant and your vinegar are compatible.
Propagating Christmas and Thanksgiving cacti is easy: just cut or snap off a stem with several stem segments ("leaves") on it. Let it air-dry in the shade for two or three days and then plant in a mix of 50% sand and 50% sterile potting soil. Water the soil when it is dry and keep the cuttings in bright, indirect light and warm temperatures. The roots form at the bottom of individual segments, so make sure at least one of the lower segments has its lower end in the soil (individual leaf/stem segments can actually root just fine, but make sure half of the segment is beneath the soil surface). If your cutting is long, feel free to bury more than one of the lower segments; but make sure at least one is under the soil. The cuttings will often wilt dramatically since they have no roots to take up water, but with regular watering when the soil is dry, they will plump up again when the roots are formed. Cuttings are easiest to take during late spring/early summer when temperatures are warm and stable.
So the general guidelines are these: keep your potted Schlumbergera plants outside as long as possible in bright shade or morning sun, water when the soil is just dry, and protect from frost by bringing them to a frost free spot but do let them enjoy the long chilly frost-free nights. That's all there is to it. If you follow these general guidelines, your Christmas and Thanksgiving cacti will get larger and showier each year.