Aloe plants, known for their green foliage, sometimes turn purple. While this color change can be concerning, it’s often a natural response to environmental cues, signaling the plant is adapting rather than in severe distress.
Understanding Why Aloe Turns Purple
Aloe vera’s green color comes from chlorophyll. A purple tinge is due to anthocyanin, a pigment produced by the plant to protect itself from environmental stressors. This protective mechanism can be triggered by several factors, causing leaves to show purple hues, often at the margins.
Too Much Sunlight
Intense or direct sunlight commonly causes aloe plants to turn purple. When exposed to excessive light, the plant produces anthocyanin as a natural sunscreen. This pigment shields the plant from UV rays, preventing sunburn and resulting in reddish or purplish hues.
Cold Temperatures
Aloe plants thrive in warmer conditions. Exposure to cold temperatures, especially below 50-60°F (10-15°C), induces stress and purple discoloration. Cold acts as an environmental stressor, prompting anthocyanin production as a protective measure against cell damage.
Water Stress
Watering practices influence an aloe’s health and color. Underwatering frequently causes purple discoloration, signaling dehydration. Overwatering can also indirectly contribute to purple leaves. Consistently damp soil leads to root rot, starving the plant of nutrients and oxygen, which can trigger anthocyanin production.
Nutrient Imbalance
Less common than light or temperature issues, certain nutrient deficiencies can also cause aloe leaves to turn purple or reddish. A lack of phosphorus can cause purpling and stunted growth. Magnesium deficiency, essential for chlorophyll, can fade green color, making purple hues more prominent. These imbalances disrupt plant functions, leading to color changes.
Is Purple Color a Problem?
Purple leaves often indicate an aloe plant’s response to environmental stress, not imminent demise. Mild purpling, especially at leaf tips or margins, can be the plant adapting, similar to a “suntan.” This cosmetic change often signals healthy stress adaptation.
However, severe, widespread purple discoloration, or symptoms like mushy leaves, stunted growth, or a soft stem, may signal a serious underlying issue. The purple color serves as a visual cue that the plant is stressed. Assessing overall health, including leaf texture and growth patterns, helps determine if the hue is cosmetic or a warning sign.
Corrective Steps for Purple Aloe
Addressing environmental factors causing purple discoloration can restore your aloe plant’s green color. Adjusting its care routine supports recovery and well-being.
Adjusting Light Exposure
If excessive sunlight is the cause of purpling, move your aloe plant to a location with less intense, but still bright, indirect light. For indoor plants, a sheer curtain can help filter strong sunlight from a south or west-facing window. When moving an outdoor aloe, gradually acclimate it to a shadier spot over several days to prevent further stress.
Optimizing Watering Practices
Allow soil to dry completely between waterings, checking the top 2-3 inches. Water thoroughly until it drains from the pot bottom, ensuring the root system is hydrated. Avoid leaving the pot in standing water to prevent root rot.
Protecting from Cold
Aloe vera thrives in temperatures between 65°F and 85°F (18°C and 29°C) and does not tolerate temperatures below 40°F (4.4°C). Move indoor plants away from drafty windows or doors, and ensure consistent room temperatures. For outdoor plants, bring them indoors before the first frost or use insulating materials like frost cloth if they cannot be moved.
Addressing Nutrient Needs
If a nutrient imbalance is suspected, consider fertilizing with a balanced, diluted succulent-specific fertilizer during the growing season (spring and summer). Aloe plants have low nutrient requirements, so dilute the fertilizer to half strength to avoid over-fertilization. Ensure the soil has good drainage, as poor drainage can hinder nutrient uptake.
Preventing Future Discoloration
Maintaining consistent, optimal environmental conditions prevents future purple discoloration. Provide bright, indirect sunlight, especially for indoor plants, avoiding harsh, direct afternoon sun. For outdoor aloe, consider partial shade during the hottest parts of the day.
Water deeply but infrequently, allowing soil to dry completely between sessions to prevent underwatering and overwatering. Use a well-draining soil mix and a pot with drainage holes. Shield your aloe from extreme temperature fluctuations, bringing it indoors below 50°F (10°C) or during cold drafts. These measures help maintain its green color.