The main cause of a cactus turning red is due to a lack of sunlight.

Why Is My Cactus Turning Red? (8 Causes And Solutions)

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If your cactus is turning red, it could be due to one of several reasons. It could be getting too much sun, not enough water, or it could be a sign of a nutrient deficiency. If your cactus is turning red, it’s important to figure out the cause so you can take the necessary steps to fix the problem. Here are 8 possible reasons why your cactus is turning red, along with solutions for each problem.