Myself, I wouldn't put that kind of mulch over seeds. If anything, something light, like grass cuttings...but very lightly. When the plants get bigger, I put mulch around them, but never up to the plant itself. It could cause the stems to rot if there's too much moisture.
Hope this helps.

Kat

The whole point of mulch is to keep sun away from the ground so that (weed) seeds cannot germinate. The same principle holds true for desirable plants. If you are looking for something light to cover the seeds as you sow them, just vermiculite. Otherwise, don't mulch until you set them in the ground or move them into their permanent pots.