Christmas cactus is a popular indoor plant because of its vibrant colors. However, seeing the purple discoloration on its leaves and stem brings concern about your plant’s well-being.
Why is my Christmas cactus turning purple? A Christmas cactus turns purple as a response to environmental stress, such as too much light, to protect itself from the sun’s rays. Other factors such as nutrient deficiency, sudden temperature drops or overwatering also lead to the plant’s discoloration.
If you’d like to know an in-depth discussion about why a Christmas cactus turns purple and ways to help it turn back to its normal color, keep reading.
What Is a Normal Color for a Christmas Cactus?
A deep, vibrant green indicates that your Christmas cactus is normal. A healthy Christmas cactus possesses plump green leaves and bears abundant flowers. Here are additional indicators of a healthy Christmas cactus:
- Green-colored stems. Yellowish or pale green stems exhibit signs of nutrient and sunlight deficiency. If the stem turns dark green or purple, it indicates getting too much sunlight.
- Glossy green leaves. Purplish shade on leaves means the plant was exposed to too much light. Colors such as yellow, orange or brown on leaves signal a problem.
- Bright-colored flowers. Flowers make a good indicator of your Christmas cactus health. A healthy Christmas cactus produces vibrant and uniform blooms. If the flowers look faded, it might be a sign that your plant doesn’t get enough light. Aside from the colors, the flower should also:
- Produce abundant flowers. If the Christmas cactus grows a noticeably small amount of flowers, it might be a sign of deficiencies in light, nutrients or water.
- The size and shape of the flowers are ideal. The flowers of a healthy Christmas cactus look large and well-formed. Small or distortedly-shaped flowers mean your plant doesn’t get enough light and nutrients.
- Long-lasting lifespan of flowers. The average lifespan of the Christmas cactus flowers ranges between four to six weeks. However, if the flowers last for several days only, your plant lacks enough water or nutrients.
Importance of Understanding the Causes of Color Change in Christmas Cactus
Knowing and understanding the changes in the color of your Christmas cactus plays a very important role in maintaining a healthy plant, providing optimal care, timing blooms and increasing propagation and cultivation measures. In the following section, we will discuss the essential factors in understanding why your Christmas cactus changes color.
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To Detect Potential Problem
When your Christmas cactus turns yellow, brown or purple, it indicates problems such as overwatering, nutrient deficiency or root rot. Color change also signals your plant experienced environmental stress or acquired diseases. By understanding why your Christmas cactus alters its color, we can identify and address the problem correctly.
To Provide Optimal Care
Factors such as the amount of water and sunlight, temperature and fertilizer affect the color of your Christmas cactus. Knowing these factors allow Christmas cactus owners, like us, to provide the right amount of care for your plants. For example, adjusting the amount of light exposure promotes more vibrant-colored stems, leaves and flowers. Also, supplying the right amount of nutrient levels and water guarantees healthy leaves and flowers.
Successful Cultivation and Propagation
Knowledge of the color change of Christmas cactus allows plant breeders and enthusiasts to successfully propagate this plant using different techniques like grafting to preserve and propagate specific color traits. They can also use the knowledge about changes in color to develop new varieties, or cultivars, with desired colors. Some examples of Christmas cactus cultivars are the Christmas Fantasy and the Christmas Flame.
Related article: Most Common Christmas Cactus Problems [+How to Solve Them]
Reasons for Purple Coloration in Christmas Cactus
Anthocyanins are color pigments responsible for the purple color of your Christmas cactus. Environmental stress factors produce these pigments on plants as their response. In the case of your Christmas cactus, anthocyanins absorb the excess sunlight to prevent damage to your plant’s cells. In other words, the Christmas cactus changes color to purple to protect itself from too much light absorption.
Aside from excessive light protection, here are the other reasons why your Christmas cactus turns purple.
Temperature Stress
Temperature changes induce the production of anthocyanins in the Christmas cactus. The cold temperature causes the accumulation of anthocyanins to prevent cold-induced damage. The ideal temperature for your Christmas cactus should range between 50 to 60 degrees Fahrenheit. Exposing your plant to temperatures below 50 degrees Fahrenheit can cause permanent damage.
Related article: How to Grow a Bigger Christmas Cactus
Nutrient Deficiencies
The purple discoloration signals a lack of nutrients – specifically magnesium and phosphorus. Phosphorous deficiency increases the development of anthocyanin levels which turns foliage to purple discoloration. It also impedes root growth. For the worst symptom, your plant becomes pale due to extreme deficiency.
On the other hand, a deficiency in magnesium turns the leaf edges purple. Magnesium is a component of chlorophyll – a green pigment in plants. When your Christmas cactus lacks magnesium, it inhibits the production of chlorophyll. To compensate for the lack of chlorophyll, your plant produces anthocyanins, which are purple pigments.
Although anthocyanins play an unnecessary part in your plant’s growth, they help protect leaves from any damage caused by too much sunlight exposure.
An ideal amount of phosphorus and magnesium for Christmas cactus is shown in the table below.
| Nutrient | Recommended Amount |
| Phosphorous | 200-300 ppm |
| Magnesium | 50-100 ppm |
Christmas cactus requires a balanced amount of phosphorus and magnesium. Phosphorus helps your plant bloom and magnesium plays an important role in photosynthesis. We can supply these important nutrients to your Christmas cactus by using fertilizer. The ideal fertilizer ratio contains 20% nitrogen, 20% phosphorous and 20% potassium.
You can provide magnesium to your plant by using Epsom salts – a natural source of magnesium. You can easily mix this with your fertilizer. The ratio of Epsom salt to give is 1 teaspoon per gallon of water.
Other Underlying Issues
Environmental stresses such as pests, improper potting soil and overwatering or underwatering cause purple discoloration in your Christmas cactus.
- Overwatering – Overwatering leads to root rot. Root rot stops the plant’s absorption of water and nutrients. This problem stresses your Christmas cactus which leads your plant to produce anthocyanins – the purple pigments in your plant.
- Underwatering – Insufficient water supply causes stress to your Christmas cactus. It attempts to produce anthocyanins to protect itself from stress. This causes your plant leaves to turn purple.
- Pests – Pests such as mealybugs, scale insects and aphids don’t directly cause the purple discoloration to your Christmas cactus. However, when they feed on the sap of your plant, it weakens your Christmas cactus. It stresses them and causes the production of anthocyanins.
- Improper Potting Soil – Using soil not appropriate for your Christmas cactus causes purple discoloration. Improper potting soil brings forth several problems such as poor drainage, nutrient deficiency and too high or too low soil pH. As mentioned, these problems cause stress that leads to the production of anthocyanins in your plant.
Natural Color Variation
Some Christmas cactus variations naturally exhibit purple color in their leaves and stem. Examples of these variations include the Purple Passion Christmas cactus, Schwarzenberg Christmas cactus and Limelight Christmas cactus. Purple leaves and stems are perfectly normal for these variations and don’t indicate problems. This means that observing the growth and overall health of your Christmas cactus helps determine if this is the case.
Will a Purple Christmas Cactus Turn Green Again?
Yes, the Christmas cactus can go back to its normal color. Here are the following steps on how to address the purple discoloration:
- Provide adequate light. The cactus needs 8 hours of indirect light per day. The ideal location to put the Christmas cactus is by the window except the south. If we place the plant in a south-facing window, use blinds or sheer curtains to filter the light.
- Fertilize using a balanced fertilizer. The ideal fertilizer formula for this plant is 20-20-20 – 20% nitrogen, 20% phosphorous and 20% potassium. It helps solve the nutrient imbalances causing purple discoloration in the Christmas cactus.
- Ensure proper watering. Soak the soil and let it completely dry before watering. Consistency is the key here. If you follow consistent and appropriate practices in watering, it restores your plant’s health and color.
- Maintain stable temperatures. We must keep the Christmas cactus in a stable temperature that ranges between 60 to 70 degrees Fahrenheit. Exposing this plant to fluctuating temperatures causes it stress, which may turn it purple again.
If the following conditions above are met and still the plant doesn’t return to its normal color, the presence of genetic factors or underlying issues may affect its ability to return to its normal color. You may want to consult a horticulturist for further assistance.
Related article: Ultimate Guide: Types of Christmas Cactus
Conclusion
Aside from its normal color variation, environmental stresses cause the purple discoloration in the Christmas cactus. These stresses include temperature stress, nutrient deficiency and underlying issues such as overwatering, underwatering, pests or improper potting soil. We can help address these issues by consistently providing the appropriate care such as addressing the right amount of light, water and nutrients. By doing these things, you can help your plant return back to its normal color.