Seed starting: yellow leaves, bolting…

[loneshepherdParticipant]

I have several seedlings that I have started (some in soil blocks, some in trays) in a grow tent with an LED grow light. They should have sufficient light, water, airflow. They were started in a peat-based potting mix and have not had any fertilizer applied.

However, some of the kale and spinach, particularly, are getting yellowing leaves and just don’t look great. I’m starting to harden off the spinach and noticed a couple of them have actually started to bolt!

They were starting around Feb 6, so the seedlings are a little under 8 weeks old.

Any ideas what’s going wrong here? Overwatering? Soil blocks / trays too small for the plant? I’ve had this problem before and need to get this figured out…

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[CleansweepParticipant]

I expect if you were to tip the tray out you would find a mat of roots at the base.I think you may have started them too soon, or should have planted them out 2 weeks ago if conditions were fit.
Basically they have done well, with the provided conditions but I feel, have outgrown their surroundings, depleted the compost and are now responding to the stress by a last ditch attempt to seed before its too late!
Spinach is especially prone to this, some varieties will bolt almost while you watch. Suggest you harvest the good baby leaves,to take some crop for your efforts, and maybe sow more outdoors now.

[charlesModerator]

Yes lone shepherd you left them way too long. Harvestable already as cleansweep says.
From that sowing date I would plant them early March with fleece over.
Aim for four week seedlings on average, see my propagation video for examples.
Small seedlings thrive in the ground which is compost initially in no dig.

[loneshepherdParticipant]

Thanks for the feedback — good to know it was as simple as that.

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