I've been doing a lot of ironing. I'm about ready to go to wash and wear and forget ironing altogether!
I got some iron pills, crushed them as fine as I could and then watered the seedling. It wasn't magic, but I ended up with concentrated green spots on the leaves. I guessed, whether right or wrong, that was where a little iron granules stuck and then got absorbed. I hope you can see it in the photo.
But that's as far as it got. Then when I was at the feedstore picking up cowfeed, it turned out they had one bottle of liquid iron on clearance because they aren't going to carry it anymore. I got that and mixed a solution carefully following directions and did a foliage spray. No help again. After a day or two I took the original solution I had made using the iron pills and drenched the soil with it. I can't tell if any of that is doing anything. The plant is getting greener, but so are some of the few that show yellow foliage that I'm not treating. I'm inclined to credit warmer temperatures. Something isn't right, but now the seedling is growing a scape, so it's managing the deficiency better than I am. It has a long way to go to reach what I'd consider a normal color, but at least the paleness coming out on new growth is uniform and not interveinal. Any suggestions? Anyone?
@sooby Sue? I haven't, at this point, done anything to the little almost white seedling.