Treat yellowing leaves by adjusting light and airflow

Yellow microgreens can have several causes, but the two most common are too little light and overwatering. The fix depends on when the yellowing appears.

Diagnosis

• Yellow after blackout removal: Normal — seedlings are pale from darkness and will green up in 24-48 hours under light. No action needed.
• Yellow after several days of light: Insufficient light intensity or duration. Move lights closer and extend to 14-16 hours.
• Yellow with mushy stems: Overwatering. Let the medium dry slightly between waterings and increase airflow.
• Yellow lower leaves only: Natural — cotyledons yellow as the plant shifts energy to true leaves.

Tips

• Don't confuse post-blackout paleness with a problem — patience fixes it
• Nitrogen deficiency is rare in microgreens since they're harvested before nutrients deplete
• If yellowing persists despite good light, try a different seed source