From our roots' perspective, water is our lifeblood, but it's a delicate balance. When you overwater us, the soil becomes waterlogged, driving out the oxygen our roots need to respire. We essentially begin to drown. Without oxygen, our roots cannot function properly; they become soft, rot, and die. This root rot means we can no longer absorb the water and nutrients we desperately need, leading our leaves to turn yellow, often starting from the lower parts. Conversely, underwatering is just as catastrophic. Without enough water, we cannot transport nutrients or perform basic cellular functions. To conserve resources, we will sacrifice older leaves, causing them to yellow, crisp, and drop. The solution is to check the soil moisture before watering; we prefer a deep, infrequent drink that allows the top few inches of soil to dry out between waterings.
We require a balanced diet of macro and micronutrients to synthesize chlorophyll, the green pigment essential for photosynthesis. A lack of key nutrients directly inhibits chlorophyll production, resulting in chlorosis, or yellowing leaves. Nitrogen deficiency is a common culprit, causing a uniform yellowing of older leaves as we move this mobile nutrient to support new growth. Iron deficiency presents differently, with yellowing between the deep green veins of younger leaves, as iron is immobile within our systems. Magnesium deficiency also shows as yellowing between the veins but typically on older leaves first. The solution is a soil test to identify the specific deficiency, followed by an appropriate, balanced fertilizer or a targeted supplement like chelated iron or Epsom salts (for magnesium).
As photosynthetic organisms, sunlight is our sole source of energy. When planted in too much shade, we cannot produce enough energy to sustain our full foliage. In this energy crisis, we are forced to ration our resources. Lower and inner leaves, which receive the least light and become less efficient, are often the first to be abandoned. We will withdraw chlorophyll from these leaves, allowing the yellow pigments (xanthophylls) to show, before eventually dropping them entirely to redirect energy to sun-exposed leaves and new growth. The solution is to ensure we receive at least six hours of direct sunlight per day. If we are in a pot, please move us. If we are in the ground, consider pruning surrounding vegetation that may be casting shade.
Our leaves can also yellow due to direct attacks from pests and fungal diseases. Spider mites are tiny arachnids that pierce our leaf cells and suck out the chlorophyll-rich contents, leaving behind a stippled, yellow appearance, often with fine webbing. Black spot, a common fungal disease, starts as dark spots on our leaves. As the disease progresses, the tissue around the spots turns yellow before the entire leaf drops. This is a defensive measure to isolate the infection and prevent it from spreading to the rest of the plant. The solution involves vigilant monitoring. For pests, a strong spray of water or horticultural oil can be effective. For fungal issues like black spot, improve air circulation through pruning, avoid wetting our foliage, and apply an appropriate fungicide, removing and disposing of infected leaves promptly.
