I had some seedlings slow to a stop this year....I suspect problems with an open bag of seed starting mix

Change it up !......Put them into some new/different mix even tho they are officially "too small"

......what are you using ?

I used Miracle Grow Seed Starter. I repotted them into 4" pots about 3 weeks ago. I use an inexpensive soil I bought from Ace. It was the only soil I could find anywhere that didn't have the fertilizer in it. It is kinda heavy. Now I know why the other tomatoes we have in pots aren't doing much. Thanks!

If they have their 1st set of true leaves, you can certainly fertilize them...unless I'm misunderstanding your original post...?

& FWIW, I could not grow Brandywines here, they have poor resistance to diseases, seemingly = (

Someone around here grew Brandywines and bragged about the taste. I thought they had to have their second set of leaves to fertilize. I have nothing to lose at this point. It's getting too late to grow them unless we can make a little room in our tiny greenhouse.