Chrysanthemums are sun-loving plants that require at least 6 hours of direct sunlight daily. When grown in low-light conditions, their leaves may turn yellow due to reduced photosynthesis. The plant prioritizes energy conservation, shedding older leaves to redirect resources to newer growth. If your chrysanthemum is indoors or shaded, consider relocating it to a brighter spot or supplementing with grow lights.
Yellowing leaves often signal root distress caused by excessive moisture. Chrysanthemums prefer well-draining soil; waterlogged roots suffocate and develop rot, impairing nutrient uptake. Symptoms include yellow lower leaves that may feel soggy. Ensure pots have drainage holes and reduce watering frequency—allow the top inch of soil to dry between waterings. For garden plants, amend heavy clay soils with organic matter.
Key nutrient shortages manifest in leaf discoloration:
Sap-sucking insects like aphids, spider mites, or thrips weaken chrysanthemums by draining nutrients, leading to yellow, speckled, or curled leaves. Check leaf undersides for tiny pests or webbing. Treat infestations with insecticidal soap, neem oil, or introduce beneficial predators like ladybugs. Severe cases may require pruning affected foliage.
Pathogens such as Fusarium wilt or bacterial leaf spot disrupt vascular systems, causing yellowing and wilting. Fusarium-infected plants show yellowing on one side first, while bacterial spots have yellow halos. Remove diseased foliage immediately, avoid overhead watering, and apply copper-based fungicides. Sterilize tools to prevent spread.
Older leaves near the base naturally yellow and drop as part of the plant’s growth cycle. If only a few lower leaves are affected and new growth appears healthy, this is normal senescence. Regularly remove yellowed leaves to maintain plant vigor and prevent fungal harborage.
Chrysanthemums thrive in moderate temperatures (60–75°F/15–24°C). Extreme heat accelerates moisture loss, while cold shocks inhibit root function, both triggering yellow leaves. Protect plants from frost with covers and provide shade during heatwaves. Potted chrysanthemums should be moved away from drafty windows or heating vents.
These plants prefer slightly acidic to neutral soil (pH 6.0–7.0). Highly alkaline soils (>7.5) lock up iron and manganese, causing chlorosis. Test soil pH and amend with sulfur to lower pH or lime to raise it. Container plants benefit from fresh, pH-adjusted potting mix annually.
Recently transplanted chrysanthemums may yellow as roots adjust to new soil conditions. Minimize stress by transplanting on cloudy days, keeping roots intact, and watering with a diluted seaweed extract solution to encourage root recovery. Avoid fertilizing until new growth emerges.
Herbicide drift or excessive fertilizer salts burn roots, leading to yellow or brown leaf margins. Flush potted plants with distilled water to leach salts, and avoid using lawn chemicals near chrysanthemums. Always follow fertilizer dosage instructions.
