What is wrong with this schlumbergera/Christmas cactus?

(Question)

I have been looking after a Christmas cactus at my work ever since I started there, and found it nearly dead in Jan 2014. With careful watering, it recovered and did very well for about a year until I went away over the holidays this past December and it went without water for three weeks (I asked people to water it but it turned out everyone else was away too). It still produced three flowers over those three weeks and was alive when I got back though the leaves were no longer plump and it had dropped its newer growths. I started watering it again (about once a week/as needed) and thought it was recovering. The remaining buds didn’t bloom and eventually fell off but I have read it is not unusual for Christmas cactuses to drop buds. It also hasn’t grown any new leaves since the new growths that fell off after those three weeks of no water but I figured it was just going through a rest period after blooming. However, starting in late February, its leaves gradually started turning brown and hard, starting with just a bit of orangy-brown around the edges then turning a lighter bright green and having the brownness spread from the outside in with only the middle stem part where water passes relatively free of the hardness. It also hasn’t developed any new growths yet even though it started getting them in February or March last year. Its soil looked poor (and had the remains of some other plants in it that died before I came) and so finally a couple weeks ago I decided to repot it into some new soil (regular potting soil mixed with about 1/3-1/2 cactus soil). But so far that doesn’t seem to have helped. It dropped a few more branches (which I’ve been trying unsuccessfully (so far) to get to grow roots) and is still developing the brown hardness and not growing anything new. I am still watering it about once a week. It is sitting in a North-facing window. There is a vent next to it (heat in the winter, air conditioning in the summer, and nothing at this time of year) but there are no windows without vents in the building and it grew fine last year despite the vent. Why is the Christmas cactus turning brown and hard? Why is it not growing anymore? Is it dying? What can I do to help it? Also, do you have any tips on how to get the branches it drops to grow? (I’ve tried just planting them and also tried putting them in water (just the bottom portion) but no success so far…) Thank you!

p.s. I have more pictures but it would only let me upload one.

(Answer)

Christmas Cactus or Schlumbergera bridgesii is a tropical cactus originally found in South America though the variety we have in our homes is actually a cross between two wild varieties. As such Christmas cactus won’t thrive in the same hot and dry conditions as cactus. In fact, Christmas cactus grows in moist forest debris rather than in soil.

Breakage of leaves and branches may be an indicator that the soil is too dry. You may need to increase your watering schedule so that the top inch of soil is moist but the plant is not so saturated that the cactus pot is sitting in water. Humidity is also a factor in Christmas cactus growth. Though most plants adjust to the relatively low humidity levels indoors putting a saucer of pebbles and water near your pot might give it an advantage.

You mentioned that it is by heating and cooling vents – in its weakened state the plant may be struggling in fluctuations of heat and now cooler temperatures. Try moving it away from the vents to a table or desk near a window till it gets a bit stronger.

Repotting the cactus was probably a good choice though pot size may be an issue. Christmas cactus tends to do well if slightly root bound (meaning that the roots are filling the pot which you can see if you gently ease the plant out of the pot). If the pot if too big it likely won’t flower and will not be getting the moisture it requires (either way too much or not nearly enough).

If your cactus is just not thriving propagation may be the best way of continuing to enjoy this lovely plant. You’ll want to use the top segment of a healthy branch, not ones that have fallen off. Trim of a few segments and plant a quarter of its length deep in slightly sandy soil. Keep evenly moist in a well lit area.  You’ll know that the cuttings are rooted when you give them a (gentle!) tug and they feel firm in the soil. This can take many weeks depending on light, warmth and moisture.

Below are a few more links that you might find helpful: