Seed-starting mix is the best option but you can also use regular potting mix or you can even make your own.
You need something to grow your transplants in. Seed-starting mix is the best option but you can also use regular potting mix or you can even make your own. If you go with potting mix, I recommend sifting it before use as it tends to be much coarser and more difficult to work with. I use this PRO-MIX premium organic seed starting mix and this Fox Farm Ocean Forest potting soil. Under normal circumstances, you should never use soil from your outside garden to start seeds. Doing so risks bringing in disease and pests from outside. But if it is all you have right now, give it a shot.