Seedlings turn yellow mainly due to a few common reasons: overwatering, insufficient light, nutrient deficiencies, or natural leaf life cycle.
- The cotyledons (first leaves) naturally yellow and fall off as the seedling grows new true leaves, which is normal and not a problem. But if the larger or true leaves are yellowing, it usually indicates an issue.
- Overwatering is a frequent cause; seedlings need moist but not wet soil. Let the soil partially dry out between waterings to avoid root problems.
- Insufficient light can cause yellow leaves. Seedlings require about 12 hours of good light daily followed by a dark period.
- Nutrient problems often stem from either too little or too much fertilizer. Seedlings typically do not need fertilizing for the first few weeks. If there is too much fertilizer, harmful mineral buildup can occur, strangling the roots.
- Nutrient deficiencies like nitrogen (general yellowing), phosphorus (yellowing with purple tinge), potassium, iron, or magnesium can cause yellow leaves if the soil lacks these nutrients.
Ensuring proper watering, adequate light, and balanced nutrients is key to preventing yellowing of seedlings.
