Jo,

I don't know these species very well, but the one that flowers in spring earned the name Easter Cactus (Hatiora gaertneri?), while the one that blooms in the fall has been called Christmas Cactus, Thanksgiving Cactus, and now the politically correct and inert "Holiday Cactus"... and there may be more than one species involved here as well as numerous hybrids.

One species flowers in response to longer days (Easter), while the other one flowers as days get shorter (Thanksgiving and Christmas). The fall/winter bloomer initiates flower buds in the fall in response to shorter days, drier conditions, and cooler temperatures, so if you protect it from all these stimuli it probably won't flower. It may require a long dark period, or no lights at night. Commercial growers quit watering them for about a month around Sept/Oct (they start to look like they are dying as they shrivel up) and also expose them to cooler night temps perhaps in the 50's F. After the dry period they resume normal watering. I don't think much fertilizer would be required at this stage. Buds should start to appear soon thereafter.

Forget about cactus soil for these types of cactus. Treat them like a tropical foliage plant during the growing season, and yes the Miracle Gro 20-20-20 is fine, and do not let them stay too dry. I would also recommend using the Miracle Gro Moisture Control Potting Mix for this type of cactus. It's an excellent soil mix and zygocactus/schlumbergera/hatiora should do well in it.

BTW you are right about being careful with an old plant like yours. Most plants, like most people, adapt to changes easier when they are younger. I would wait for springtime and better growing conditions before repotting it.

Hope this helps!

Peyton

Ladynine, what you have here is a real "old style" Christmas Cactus. It should normally flower during the winter. Easter Cactus (Hatiora Gaertneri) looks different, you'll find pictures on the Web. I would suggest taking cuttings later this year, as insurance.

HTH