I get bales of Promix from Menards. Works fine for me. Think maybe you just got a bunk bag? Was this bag from a different purchase than the one you just used up?

Was this bag from a different purchase than the one you just used up?

Yes. Two years apart. I bought the second bag at the end of last summer knowing I'd need it for this year's plants.

I use pre-made, local nursery brand.

Maybe since they were different batches you got a bunk bag. Since it's been two years I hope it's not a case of they changed formula or sources and that's an issue.

Nothing sacred about store-bought germinating mix. You can easily make an adequate mix at home. Should have some natural soil for minerals, sifted to remove pebbles and large debris,, and a component like peat moss or compost to fluff up the mix. Best to heat sterilize it to avoid damplng off. Many recipes available.

daninthedirt, I realize some people prefer to make their own, that's why I asked. My personal preference is ready made.

I went to the nursery today to buy a larger bag of Fox Farm Ocean Forest potting soil. I used some yesterday to re-pot a couple dozen tomatoes. The change in their appearance in just 24 hours was amazing. I'll do the same tomorrow with the rest. I didn't see any seed starting mixes at the store. At this point I'm thinking about trying Fox Farm's Light Warrior seed starter next year.

https://foxfarm.com/product/light-warrior-seed-starter

I've seen some of the fox farm products in stores around here, but I haven't tried any of them yet. But yay that a soil switch out has worked! Hopefully they will thrive in their new soil :)

I don't use seedling starter mixes at all. I've read you need a sterile mix void of nutrients for starting seedlings and most are. but I think otherwise. In nature there is nothing sterile when a seed falls to the ground which usually has nutrients in it. So I just use a potting mix of any brand to start and grow seeds, and once I get true leaves I start sprinkling a glandular fertilizer other the top every week or two. I really don't like re-potting if I can help it and like to start and grow in one pot.

SunGro Professional mix was obviously missing something the fox farm had. Glad to hear your tomatoes are doing good now.

One month of progress growing Brussels sprouts directly in one pot to move directly to the ground.

It's true that upon germination, seeds don't really need nutrients, because the cotyledons, which are already formed inside the seed, have the nutrition needed to sustain seedling growth for the first few days or so. But after that, added nutrients are very important. So just-germinated seedlings are pretty self-sufficient, but beyond that, they're going to be real hungry. I don't plant out for several weeks, so adding half-strength fertilizer is essential. True, the mix itself need not contain much of any nutrients. In my mind, seed starting mix need only be something friable that holds moisture, and I'm not going to spend money to get that. As to sterility, sure, seeds fall to the ground which isn't sterile, but betcha not a lot of them survive.

Back when I started most of my plants from seed I never had a problem using Jiffy Seed Starter Mix. I did add about a pint of boiling hot water to the bag one day before using it to hold down the dust, electrostatic properties, and also made it easier to work with when filling cell packs. Adding the hot water to the mix also aided in water absorption with the first seed watering.