I originally posted this in the Vegetable Gardening Forum, but thought I'd get some good advice here as well:

This week I've noticed that the cotyledon leaves on all my cole crops are yellowing (kale, cabbage, tatsoi, pak choy, and broccoli). They were transplanted out into 8" raised beds using the square foot system two weeks ago and were looking great until recently. They now have about two sets of true leaves that are looking lovely, but the cotyledons are yellowing and I don't want it to get worse.

The soil mix is 1/2 organic compost, 1/4 vermiculite and 1/4 peat moss (give or take). Since there are a lot of nutrients in the new soil mix I doubt there would be a nitrogen issue, but do correct me if you think I could be wrong.

We had a ton of rain last week and cold temps but the cole crops were proected with row covers which were removed the following morning. Now it is in the upper 70's, low 80's and sunny this week. Could they be in shock with the sudden transition?

On another note, I kept a few "extra" seedlings from thinning and transplanted them into small pots filled with potting soil for friends. Those plants look great with no yellowing, which leads me to suspect it is a soil issue in the new raised beds. I'd love and ideas or advice, since this is my first year attempt at raised beds and don't want to lose my little seedlings! (My other crops seem to being doing great in the new soil mix though)