That's pretty wild. If I didn't think that the soil were exactly the same, then I'd be questioning that. But right now, looking at what happened with a HUGE batch of seeds I started in February, yadda yadda yadda, I find myself wondering if perhaps just the slightest difference in location might be what's causing it.
Have you tried giving it a big push of nitrogen, and maybe some alfalfa tea?
This is progressing into an interesting discussion involving the earliest possible time to put plants out in Northern California...
With seed starts, I've put them out as early as March, as seedlings. Then just let them do their thing whenever it happens. Which is to say that when it's cold, nothing happens, so there's kinda no point.
My plants are on the porch under a painters tarp (to help insulate the heat during the 48 degree nights. The lights go on shortly before sunrise and go on again in the morning about an hour before sunrise equaling 8.5 hours in darkness. I'm hoping this will help the process of transitioning them into 10 hour dark nights that are rapidly approaching.
I would to put then out on this next full moon which is may 14th...but the nights are still a tad cold so I'll probably rock the third week of May as to get monsters.
If anyone wants to share their hardening off process that would be awesome.
There are a couple of ways to do this. You can put them in dappled shade and move them to sunnier positions through a week's time. You can use something like landscaping or shade cloth, pulling it back for a couple of hours at first in the morning and evening, then extending that time. If you have something like a greenhouse then they can go directly from the GH to full sun IME.