Seedling growth slowing post-transfer
Forgive the novice question; I am relatively new to gardening. I grew a bunch of veggies/herbs from seed and most of them did well, grew to seedlings within a few weeks. At around week 4, I transferred them to a big planter box (about 9x5) and since the transfer (about 3 weeks ago), several of the seedlings have slowed down almost completely. The broccoli, in particular, looks like it's about to die and hasn't grown at all. I have onions, thyme, oregano, rosemary, lettuce & spinach as well. And all have pretty much shown 0 growth. The soil mix was 50% topsoil & 50% organic compost. Am I missing some key nutrients?
I live in Oakland so the temps have been consistent. They get excellent sun.
Thanks for any insights/advice you can offer.