Seed shell stuck on the seedling's first leaves
Right after emergence; the cotyledons can't open..
- Also called
- helmet head
- seed shell stuck
- cotyledons trapped in seed coat
- seedling can't shed its shell
Likely causes, most likely first
Ranked for this sign on its own. Your stage, medium and readings change the order, so run the checker for your plant.
LikelySeed coat stuck on the cotyledons (helmet head)
Fix: Mist the shell to soften it and raise RH around the seedling (dome) for a few hours; if it is still stuck, ease it off gently with clean tweezers. Plant seeds about 0.5-1.5 cm (1/4-1/2 in) deep so the medium scrapes the coat off on the way up.
Recovery: Cotyledons open within a day.
How to confirm it
- Check temperature and RH at canopy height with a calibrated sensor. Put a calibrated sensor (salt test: a sealed bag with damp table salt reads 75% RH after 8-12 hours) at canopy height, out of direct light, and log for 24 hours including lights-off. Look for lights-off RH spikes and dew point.
Look for
Seedling with the seed coat clamped over the cotyledons..
The full guide: What do I do if the seed shell is stuck on my seedling?
Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.
