Why Your Seedling Leaves Are Yellow (4 Causes)
Seedling yellow leaves come from 4 causes: overwatering, not enough light, nutrient deficiency, or cold stress.
The 4 Causes
Cause 1: Overwatering (Most Common)
Signs: All leaves pale, soil wet, leaves droop. Fix: Stop watering. Let soil dry.
Cause 2: Not Enough Light
Signs: Lower leaves yellow, plant is leggy and pale. Fix: Move to brighter light.
Cause 3: Nutrient Deficiency
Signs: Older leaves yellow first, plant is stunted. Fix: Fertilize lightly (1/4 strength).
Cause 4: Cold Stress
Signs: Leaves yellow or purple, plant stopped growing. Fix: Move to 65-70°F.
The Diagnosis
| Sign | Cause |
|---|---|
| Wet soil + droopy | Overwatering |
| Leggy + pale | Not enough light |
| Old leaves yellow, stunted | Nutrient deficiency |
| Purple tinge, cold location | Cold stress |
Common Questions
Should seedlings be fertilized? Not until they have 2-3 sets of true leaves.
Will yellow leaves turn green? Usually no.
How much light do seedlings need? 12-16 hours per day.
Why are only the bottom leaves yellow? Nutrient deficiency or light issue.
Can cold cause yellow leaves? Yes. Below 60°F.
How long until they recover? 1-2 weeks.