Why Your Seedlings Are Purple (Usually Cold)
Purple seedling leaves usually mean cold stress or phosphorus deficiency. Both are fixable.
The 2 Main Causes
Cause 1: Cold Stress (Most Common)
Signs: Purple tinge, plant stalled. Cause: Below 60°F. Fix: Move to 65-70°F.
Cause 2: Phosphorus Deficiency
Signs: Purple on old leaves first. Cause: Soil lacking phosphorus. Fix: Fertilize with phosphorus.
Naturally Purple Varieties
Some varieties are purple from the start:
- Purple basil
- Purple kale
- Red cabbage
- Beet greens
How to Tell the Difference
| Sign | Cause |
|---|---|
| Purple appeared overnight | Cold stress |
| Purple on old leaves, stunted | Phosphorus deficiency |
| Variety is naturally purple | Normal |
Common Questions
Is purple bad for seedlings? Not always. But it signals stress in most varieties.
Will purple leaves turn green? If cold was the cause, yes.
Should I fertilize purple seedlings? Only if temperature isn’t the issue.
Can cold kill seedlings? Below 40°F, yes.
Why is only one seedling purple? Closest to the cold window.
Do all varieties get purple in cold? No. Tomatoes, peppers show it most.