NOTES ON CULTURE OF CHRISTMAS CACTI

Xmas cacti like cool, humid conditions and an open soil mix.  They are 
tough plants, but their weakness is rot when the stems are exposed to
soggy soil for a long time, particularly if it's hot out.  

Ideal temps about 50-65F (9-18 C) but will tolerate down to freezing and
up well into the 90s (32-36 C).  Needs SHADE or filtered light (here at 
40 degrees north latitude, they can only take full sun in winter, not 
after February).  

In the wild they live on trees in tropical cool forests.  Is an EPIPHYTE, 
*not* a soil-growing plant, so must have very very open potting mix, especially
when air is humid, or will rot at soil line.  I plant in a mix of tiny
bark chips and shredded treefern root and perlite. They can even be grown
bare on slabs of treefern bark.  The mix they come in when you buy them 
is invariably full of peat; I have never been able to keep one alive in 
such a mix for very long.  I realize the growers grew them in this mix 
but my statement stands.  

Xmas cacti are weird because they like cool humid air but not too much water.
People say not to let them dry out, but this has
not been my experience at all.  I find you must let the pot get dry before
watering again - not bone dry for weeks and weeks like a terrestrial
cactus, but bone dry for a few days until you notice the segments losing
turgor.  I have NEVER lost a root to drought. But remember that it's
quite humid here in the Midwest and so perhaps such advice comes from
growers in the western US where the air is much dryer.  

In very hot and humid conditions, only someone with a very open mix 
and a very careful hand with the water can keep one from rotting.  
If you have air conditioning I would bring them indoors
when the temp hits 85 (29C).

When these cacti bloom, their leaves ALWAYS wilt.  The flowers transpire 
so much water that the roots can't keep up with them.  You would expect 
it only to have as many flowers as the roots can support, but Christmas
cacti bloom with total disregard for this issue.
Perhaps they would not wilt as much at lower temperatures - mine are at 
70F or higher during the day - or perhaps a plant with a much larger root 
system would wilt less.  Regardless, this wilting is deceptive.  
Continue your normal watering regime, or slightly increase it, but don't 
try to keep the segments turgid when the plant is in full bloom; doing so 
will only make them rot at the base instead.  The plant looks like it's 
near death, but it's not. It fattens back up as soon as the flowers 
fall off.