Christmas cactus - Knowledgebase Question

Sloansville, Ne
Question by plstory
January 3, 2011
My cactus branches are turning red. I have 2 plants doing it, one looks a little wilty all though I water weekly. The other is very healthy just red branches. The rest I have are nice and green. The red ones turned last year, before that they were green also. Any help would be appreciated.


Image
Answer from NGA
January 3, 2011

0

The red leaves on your Christmas cactus indicate that it has experienced some type of stress. This is usually related to a lack of nutrients and being exposed to excessive bright light (like being set outdoors in the sun). Leaves contain a flavonoid called Anthocyanin, which functions to provide the colors we see in flowers and fruit. In some plants, it is also thought to protect leaves from ultraviolet radiation. (In other plants, it's thought to repel browsing herbivores!) Leaves also contain carotenoids called Xanthophylls. These also help absorb and dissipate any damaging excess light energy that cannot be harvested by the leave's chloroplasts and turned into food. The red leaves on your cactus are an indicator that it has suffered sunburn. This could be from sudden exposure to excess light, or due to the fact that is lacks the nutrients necessary to help filter out damaging ultraviolet light. Check to see that it isn't pot bound, which can affect the root's ability to take up nutrients. As long as it's not pot bound, a dose of fertilizer will probably be enough to turn the leaves back to green again.

Good luck with your Christmas cactus!

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