Since you have already done it, you might want to get back to us in a few weeks and tell us if it works. Everything I have read suggests that you may have more problems with fungus and disease.

Are the seedlings in the pots ONLY until you can plant them in the ground? If so they should be ok. I would not recommend keeping them in the pots for the whole season. If I were to grow vegetables in containers I would want a soiless mix that would not collapse and rot the roots. Al

Thanks guys.
They're going to be planted in my garden in a month or so.
Right now they're sitting in my greenhouse and seem fine. I am a little nervous about their roots, the compost is loose and spongie.

What kind of compost? I mix in the potting soil Humus (bought) along with Sphagnum moss and Perlite and all my plants are doing fine.

The compost is made up of leaves, kitchen scraps, grass, horse manure/shavings, coffee grounds and eelgrass.

It's been almost a week and I have no noticeable problems, though the seedlings don't look like they've grown any, but that could be my eyes.

Take some pictures of them, so that you can be more accurate in your growth observations. Secondly, you could measure and record the exact heights, widths, etc. of the plants to determine growth.

Most of the time when plants are transplanted, there is a period of adjustment, and if the roots have more room to grow, they will expand before you see any growth on the top of the soil.

Nothing to add except that I'm alarmed that your compost contains horse shavings :P

And let me tell you, it wasn't easy!
have you ever tried to shave a horse before? Takes a lot of razors and band aids!

You might want to watch or tweek your watering regime. The compost will act much differently than a soilless mix...the compost may not move water throughout the container like you normally are used to. Bottom watering will become a whole different beast...so feel the weight of the container...don't go by looks alone.