Hi--I have a small organic market garden in southeastern South Dakota. I am putting together a Cornell Mix for seedstarting this year (the peat/vermiculite/perlite combo) and am wondering what I should use for fertilizer. I have heard that fish emulsion and the like won't work in a soil-less mix because there aren't organisms in the mix to fix the nitrogen for the seedlings. Any ideas?
Thanks. Rebecca.

compost tea and vermipost do quite well. My seedstarting mix is perlite, coir, vermipost. Have great luck with it.

No matter if you garden in the soil, or in containers, there are plenty of beneficial microbes in mature homemade compost.

Compost will supply plenty of microbes for feeding and protecting your plants, while the humus in compost will supply plenty of chelating, or "soil magnet-sponge" powers to hold nutrients near your plant roots.

Also any fish or seaweed tea will breed beneficial soil/composting microbes from the compost mixture in a potting mix, or from the soil.

Aerated compost tea recipes are the best, for maximizing a variety of aerobic microbial species and activity, near the plant's roots (rhizosphere), and even on the plant's foliage (phyllosphere).

All microbes love sugary substances like molasses or corn syrup, in tea recipes, in order increase microbial growth. Since all sugars are high in carbon, they also help chelate, balance, and buffer nutrients to plant's foliage and roots, from foliar/soil drenches.

Plants can absorb 20 times more available nutrients and disease-fighting substances, from foliar feeding, than from just soil drenches, or from dry soil amendments alone.

The only thing seeds need to germinate is moisture and warmth, some more warmth than others. They don't need any fertilizer until after their first true leaves have formed and then not much. Whichever "fertilizer" you do use, if it has a number showing a percentage of Nitrogen, that is readily available, soluble, and does not need soil microbes to make it available to the plants. I've not fed any of the seedlings I start until just before they are ready to be planted and then they get a couple of doses of half strength fish emulsion over a two week period.

Last year I waited until I repotted my seedlings out of cell packs and into larger pots before I fed them. I think I ended up feeding them too much (nitrogen) because I had aphids sucking on my bell pepper plants by the time they were about 3-4" high. I even used half of the recommended amount of fertilizer (Whitney Farms). So I soaped them up and hoped for the best. They did okay, but my peppers came in later than expected.
I have to agree with the Captain and say using a compost tea is the way to go. That is my plan this year. I also like to foliar feed and enjoy the quality time spent pampering my plants this way. Hope you find something you like!