The Christmas cactus has a talent for causing confusion.
A large part of this is the fact that many growers mix up this Schlumbergera with its siblings, the easter cactus and Thanksgiving cactus.
This can lead to a plant that doesn’t bloom when you expect it to.
But there’s another issue that can cause a lot of head-scratching, and that is when the leaves of your Christmas cactus turn purple.
Why are My Christmas Cactus Leaves Turning Purple?
It’s normal to see a bit of purple tint on a Schlumbergera, but not for it to become the dominant color.
Caused by improper care, this discoloration is easy to diagnose and remedy. Here are the most common reasons:
Improper Watering
Giving your Christmas cactus too much or too little water is an easy mistake to make, but it can have serious consequences.
Underwatering can lead to several symptoms, with purpling being a less common one.
In the event you’ve returned from vacation to find the soil completely dry, don’t pour a gallon of water on your plant. Slowly add a small amount of water every day for 2 to 3 days until the soil is moist at the drainage holes.
Overwatering is far more serious, as the purpling could be a sign of root rot.
Root rot happens when the plant’s roots are exposed to too much water and prevents the roots from absorbing water and nutrients properly.
It can also kill the plant if not treated quickly enough.
To prevent watering issues, practice the soak-and-dry method with your Christmas cactus.
This means checking the soil every few days and watering only when it’s dry ⅓ of the way down the pot.
Add the water slowly and evenly until it begins to seep from the drainage holes.
Nutrition Or Better Malnutrition
You probably already know that plants need nitrogen, phosphorus, and potassium (the NPK in fertilizers), but that’s not all they need.
Trace minerals such as iron and copper also play an important role.
However, Schlumbergeras need a much higher magnesium content than most plants. The common symptom of a magnesium deficiency is that the Christmas cactus plant starts turning purple.
It’s generally a good idea to give your Christmas cactus a diluted balanced liquid houseplant fertilizer every other week from April to October, then stop for the winter.
To combat a magnesium deficiency, you may also wish to add a teaspoon of Epsom salts to the soil as well.
Just be sure to do the salts on the weeks you don’t fertilize and vice-versa so the plant isn’t overwhelmed.
Overcrowding
As with most plants, Christmas cacti need to be repotted every few years to replenish the soil and give them room to grow.
When one of these plants becomes rootbound, it can result in the roots being unable to draw sufficient food from the soil, resulting in malnourishment.
It’s easy to diagnose this as the cause by looking for roots poking out of the container’s drainage holes.
You should repot a Christmas cactus every 2 years in the spring, graduating to one container size larger as needed.
Note, however, that Christmas cacti actually like to be a little root-bound, so don’t rush to repot out-of-season unless the plant is showing signs of extreme distress.
Too Much Direct Sunlight
A very common cause of purpling, especially in the summer months, is exposing your Schlumbergera to too much sunlight.
As is the case with most houseplants, Schlumbergera is adapted to live on a forest floor, sheltered by trees.
As a result, you should avoid exposing it to direct sunlight, especially at midday (a little morning or evening sun is okay in moderation).
Ideally, you should have your plant in indirect, bright light or filtered sunlight, such as behind a sheer curtain.
Fixing this particular problem is as easy as moving the plant to a slightly less sunny spot.
Temperature Issues
Fluctuations in temperature can turn a Christmas cactus purple, just like it can to people.
Ideally, the plant should be kept in temperatures of 70° to 80° degrees Fahrenheit during the day and 60° to 65° degrees Fahrenheit at night.
It’s also best to keep the plant sheltered from drafts or direct line of fire of air conditioners and heaters.