Mint plants thrive in bright, indirect light. If your mint is turning yellow, it may not be receiving enough sunlight. While mint can tolerate partial shade, prolonged low light conditions hinder photosynthesis, leading to chlorophyll breakdown and yellowing leaves. Ensure your plant gets at least 4–6 hours of sunlight daily. If grown indoors, place it near a south- or west-facing window or supplement with grow lights.
Mint prefers consistently moist soil but is highly susceptible to root rot if overwatered or planted in poorly draining soil. Yellow leaves often signal waterlogged roots, which suffocate and decay, depriving the plant of nutrients. Check the soil moisture before watering—stick your finger 1–2 inches deep; if it feels wet, wait. Use well-draining soil and pots with drainage holes to prevent excess water retention.
Yellowing leaves can indicate a lack of essential nutrients, particularly nitrogen, iron, or magnesium. Nitrogen deficiency typically causes older leaves to yellow first, while iron deficiency leads to yellowing between leaf veins. Magnesium deficiency shows as yellow patches with green veins. Feed your mint with a balanced, water-soluble fertilizer every 4–6 weeks during the growing season. For iron or magnesium issues, consider adding compost or a targeted supplement like Epsom salts (magnesium sulfate).
Pests like spider mites, aphids, or whiteflies can sap nutrients from mint leaves, causing them to yellow and wilt. Inspect the undersides of leaves for tiny insects, webbing, or sticky residue. Treat infestations by spraying the plant with a mixture of water and mild dish soap or neem oil. Isolate affected plants to prevent pests from spreading to nearby greenery.
Fungal diseases, such as mint rust or powdery mildew, often manifest as yellow spots or patches on leaves. These thrive in humid, overcrowded conditions. Remove infected leaves immediately and improve air circulation around the plant. Avoid overhead watering to reduce moisture on foliage. For severe cases, apply an organic fungicide like copper spray or sulfur powder.
Mint prefers moderate temperatures (60–70°F or 15–21°C). Extreme heat or cold can stress the plant, leading to yellow leaves. In hot climates, provide afternoon shade to prevent scorching. In colder regions, protect outdoor mint from frost by mulching or moving potted plants indoors. Sudden temperature fluctuations can also trigger yellowing, so keep the plant in a stable environment.
Older mint leaves naturally yellow and die off as part of the plant’s growth cycle. If only the lower leaves are yellowing while new growth appears healthy, simply prune the aging foliage to redirect energy to younger leaves. Regular harvesting or trimming encourages bushier growth and prevents legginess.
Mint grows best in slightly acidic to neutral soil (pH 6.0–7.0). Highly alkaline or acidic soil can lock up nutrients, causing yellowing. Test your soil’s pH with a kit and amend it if needed. To lower pH, add peat moss or sulfur; to raise pH, incorporate lime. Maintaining the right pH ensures nutrient availability for healthy green leaves.
