What's up with my seedlings??

[TomatoGirl]

Not sure what's going on with my seedlings right now. About half of them are getting crispy/limp leaves.
They are under grow lights, 6 inches away, 12 hours a day. They were repotted 2 weeks ago in promix organic garden and herb. Some are thriving and double the size. I'm keeping soil consistently damp and watering every 2-3 days as needed. Any clues? One of my more sensitive varieties is also getting leaf curl, this normally happens when I transplant it, although it didn't this year and is just starting to do it now.
Last photo is of big healthy brandywine.

[TomatoGirl]

First one is healthy plant. Sorry. Loaded the last one first.

[imafan26]

It looks like it is time for them to go out already. Tomatoes are heavy feeders once they get true leaves they need to be fed and be planted in the ground.

[applestar]

I associate this kind of damage with too-heavy anaerobic soilmix in containers or clay-heavy ground. -- I've seen it reported with Miracle Gro Moisture Control -- I hadn't seen this particular ProMix product before and I'm not seeing very much info on-line so maybe it's a new formulation?

A quick search -- it seems to be described as can be used in-ground or in containers but right away that sounds a bit iffy. Is is very moisture holding? Is there enough perlite to make it well draining?

If you only made holes in the bottom of the cups, that might be creating an issue, too. It's a good idea to make holes that won't get blocked when the cups are sitting flat on a flat surface. Instead of making holes, I snip 3-4 pieces from bottom corner of the cup with utility scissors and make several slits up the sides of the cups with a box cutter when using tall containers like this.

[TomatoGirl]

Unfortunately weather here won't permit me to put these out until after 24th of May here. Too cold and we are having a LOT of heavy rain right now. I can't repot them in to bigger containers either because then I won't have room under my lights.

It looks like it is time for them to go out already. Tomatoes are heavy feeders once they get true leaves they need to be fed and be planted in the ground.

[TomatoGirl]

There isn't a ton of perlite, but it looked ok to me. It came pretty highly recommended and up until recently they had been fantastic since I planted them in it. Growing amazing. So I'd be surprised if it was the soil.
I'll cut some slits in the bottom as yes I had only made holes.
By the dried wilting leaves I thought I was under watering but I always test how damp the soil is before watering.

I associate this kind of damage with too-heavy anaerobic soilmix in containers or clay-heavy ground. -- I've seen it reported with Miracle Gro Moisture Control -- I hadn't seen this particular ProMix product before and I'm not seeing very much info on-line so maybe it's a new formulation?

A quick search -- it seems to be described as can be used in-ground or in containers but right away that sounds a bit iffy. Is is very moisture holding? Is there enough perlite to make it well draining?

If you only made holes in the bottom of the cups, that might be creating an issue, too. It's a good idea to make holes that won't get blocked when the cups are sitting flat on a flat surface. Instead of making holes, I snip 3-4 pieces from bottom corner of the cup with utility scissors and make several slits up the sides of the cups with a box cutter when using tall containers like this.