African violets, known for their velvety leaves and vibrant blooms, are a favored houseplant. When an African violet begins to show distress, the most common outward sign is the yellowing of its leaves. This change in foliage color, known as chlorosis, is a symptom indicating an underlying problem with the plant’s environment or care regimen. Diagnosing the exact cause requires careful observation of the yellowing pattern and the plant’s overall condition. The following sections explore the primary reasons why African violet leaves lose their deep green color.
Water Related Issues
Improper watering is the most frequent cause of African violet decline, with both too much and too little moisture leading to leaf yellowing. Overwatering quickly becomes a serious problem because it deprives the roots of oxygen, creating conditions for fungal pathogens that cause root rot. When the root system is compromised, it cannot absorb water and nutrients effectively, causing the leaves to turn yellow and often feel soft or mushy, typically starting with the lower, older leaves.
Underwatering presents a different set of symptoms, as the plant attempts to conserve moisture by sacrificing older foliage. In this situation, the leaves, usually the lowest rows, will turn pale yellow, wilt, and often feel dry or crispy. The soil will feel completely dry to the touch, which is a clear indicator of dehydration.
To prevent both extremes, growers should only water when the top layer of soil feels slightly dry to the touch. Many growers prefer bottom-watering, where the pot sits in room-temperature water for about 30 minutes, allowing the soil to wick up the moisture it needs. Using tepid water is also important, as cold water can shock the roots and cause yellow or bleached spots if it splashes the foliage.
Light and Temperature Stress
The placement of an African violet significantly affects its leaf health, with both inadequate and excessive light causing distinct forms of yellowing. Too much light, particularly direct, intense sunlight, can cause the leaves to suffer from sunburn or bleaching. This damage typically appears as pale yellow, white, or brown scorched patches in the center of the leaf.
Conversely, an African violet not receiving enough light will struggle to produce sufficient chlorophyll, which gives the leaves their green color. This light deprivation results in the plant’s foliage becoming a uniform pale green or yellowish hue. The leaf stems (petioles) often stretch out in an attempt to find a light source. Ideally, African violets thrive in bright, indirect light, such as that found near an east-facing window or under grow lights for 10 to 14 hours daily.
Temperature stress also contributes to leaf discoloration, especially when the plant is exposed to cold drafts. African violets prefer consistent temperatures between 65 and 75 degrees Fahrenheit. A sudden drop in temperature, such as from an open window or an air conditioning vent, can cause the leaves to turn yellow, curl downward, or even develop black, necrotic patches around the edges.
Nutritional Imbalances
Beyond environmental factors, the availability of nutrients in the soil directly impacts leaf color and plant health. Nitrogen deficiency is a common nutritional cause of generalized yellowing, as this element is a fundamental component of the chlorophyll molecule. When nitrogen is scarce, the plant mobilizes the nutrient from older, lower leaves to support new growth, causing the older foliage to uniformly turn light green or yellow.
Another factor is soil pH, which dictates the availability of micronutrients for plant uptake. African violets prefer a slightly acidic soil range, ideally between pH 5.8 and 6.2. If the soil becomes too alkaline or too acidic, the plant experiences “nutrient lockout,” where essential elements like iron or magnesium become chemically unavailable.
This inability to absorb nutrients leads to chlorosis, mimicking a deficiency. To address these imbalances, use a fertilizer formulated specifically for African violets and repot the plant annually. Repotting with fresh African violet potting mix helps to refresh the soil composition and remove accumulated mineral salts that can interfere with nutrient absorption.