They look like thirsty, to me.
That soil (5-1-1 ?) is coarse and it can dry up real quickly in those starter pots.
Seysonn.

Foliar feeding ? Those seedling roots need moisture. I wouldn't do foliar feeding on them. Foliar feeding a supplement and bypass of the root system.
Maybe the fertilized in the foliar spray was too strong and got them. Just guessing.

Have you water them yet ?

Seysonn

Foliar feeding is a scam, plain and simple.

It is not beneficial to a healthy plant in any way. There are no nutrients that they take up better or faster through the leaves than they do through the roots.

The *ONLY* reason to foliar feed is when a plant has *EXTENSIVE* root damage and is incapable of taking food/water through them. Cuttings benefit from foliar feeding because they have no roots. Plants with almost total root rot can benefit from foliar feeding.

Any normal healthy plant however will get no benefit from it short of what drips off the leaves and onto the ground as regular fertilizer.

Why do they sell specialized foliar feed? Because there was a fad about it and they realized they could make money off of giving people what they wanted instead of educating them better.

I think they dropped below freezing... do the leaves look messed up, like they had frozen and thawed out? If you water them in the shade and they don't pop back up pretty quickly it isn't lack of water.
If they froze, im sorry for your loss.

Looks like frost damage to me, personally, but I'm not as much of an expert.