Depends on temperature, watering and light... I'm assuming you mean the 'Christmas' or 'Easter' cacti - ours seems to do it's own thing if I remember to water!

It was hidden in a ceramic trough on a south facing bay window next to a crown of thorns and a pelargonium. Thing is the pot is tall but flowers hit the sill. Very festive for november

If it has long, trumpet-shaped blooms, then it is a "Christmas" cactus (Zygocactus). If it has simple cup shaped blooms, then it is an "Easter" cactus (Rhipsalidopsis). The former blooms around 3-5 weeks after the nights are long enough, while the latter blooms around 12-15 weeks after the nights are long enough. When the plant decides the nights are long enough depends on its light exposure, and the amount of artificial light it gets. It sounds like this one was being shielded from the living room lights by the other plants, so it bloomed nearly on time, unlike most of the ones that I have owned!

I wonder if it is a schlumberga They are a genus of succulent rather then a true cactus that flower from nov. onwards. mine are starting to flower now.

We don't close the curtain facing south ...so african violets are happy there too. I think it is a shlum thingy ...but the colour is different to all those seen in local garden centres.
We have a tropical trumpet pink flower from Chile I think...Looks like pink lips!!!. It grows tall but I broke it. Replanted the broken one so now I have 2....Can't remember the name tho!!

I am behind the times! :/ Apparently plants formerly named Zygocactus are now classified as Schlumbergera, while Rhipsalidopsis is now Hatiora. Schlumbergeras are true cacti, but they are so highly modified from the traditional cactus plan that most people don't recognize them as such.

you are correct Tug about their classification. I was repeating what I heard at a recent lecture on houseplants for Christmas. I 'd always been under the allusion they were cacti but when one has an expert giving a talk well..... so much for the expert! I should have checked in my RHS book before posting :o)

In the old days I thought it was a/desert b/forest.....oh well....by nest yr we may have s th else to reclassify.