I bought a Rebutia krainziana cactus from a plant show in San Francisco last spring. At the time I bought it, the cactus looked as it should; short, round, plump, spiral pattern of spines, and was blooming. I decided to keep this cactus on my work cubicle, which is next to a window. However, over the summer the cactus grew to be an irregular shape…it’s now very tall (10cm), and cone shaped. The top of the plant is very narrow, and it slowly starts to round/plump out towards the lower half of the plant. The spines are also no longer arranged in a spiral shape and are not fully formed (there are very few actual spines in the white spots on the upper half of the plant). Other than the abnormal shape of the cactus, it looks perfectly healthy. I’m just wondering what’s going on with the plant, and if there is anything I can do to get it back to its original round, plump shape. Could lighting be an issue?
It sounds like it is not getting enough light. Can you send a photo or
bring it by the nursery? Anyway, try getting it a minimum of 4 hours
direct sun, or adding a full spectrum light bulb within 12″ of the
Per your request, attached is a picture of my Rebutia. Would it be okay to keep my cactus outdoors (I live near ocean beach in San Francisco), or is San Fran weather too cold for it?
That is an extreme case of not enough light. Quite the interesting shape!
It can survive just fine outside in SF, but it would do better in a terra cotta pot with a fast draining cactus soil, and no saucer – you never want it sitting in water.
When you bring it out into the sun, it will need to be “hardened off” which means giving it progressively more light over a couple weeks, and not putting it straight into full sun.