The holiday cactus refers to a number of different houseplants: the Thanksgiving cactus (Schlumbergera truncata), Christmas cactus (Schlumbergera bridgesii), and Easter cactus (formerly Schlumbergera gaertneri, now Rhipsalidopsis gaertneri). Although technically different plants, they all have very similar needs and come with the same room for errors, especially when it comes to fertilizing.
It doesn't matter if you're caring for a Christmas cactus or caring for a Thanksgiving cactus, all holiday cacti can be harmed if fertilized in January due to this being in the middle of the dormant season. This is even true for the Easter cactus which is yet to bloom at this point in the year. Fertilizing now may result in symptoms like discoloring foliage and bud drop.
