|Your giant Vanilla Marigolds germinated in two days and continued to do well. However, after about six weeks, they are 10-12" tall and have just started to turn yellow. They are still in the 2" cells and the roots are lying in water. I'm going to transplant them today into 3-4" pots.
What else do I need to do to get them green again.
I also will begin using a dilute liquid fertilizer but not on the leaves.
|I believe you've answered your own question! It sounds like the seedlings are potbound and in need of nutrients. Once you repot them, put them under a grow light or in partial sun for a few days before putting them in full sun. This should do the trick!
Ideally, you should transplant your seedlings before the pots are packed with roots, and fertilize them with half-strength fertilizer as soon as the first "true" leaves appear. The first "leaves" that appear after germination are the leaves that were inside the seed. All the leaves that grow after that are "true" leaves. Enjoy!