After the tap root appears

Seedlings like slightly warmer, humid air. Their entire mass is brand new growth with a thin cuticle, very little defense against the elements; so think of a nice gentle environment for them to get a solid start. You can really plant the seedlings in most any kind of mild potting soil. It is also recommended to mix in some additional perlite for drainage. These babies don't want the soil to be WET, just moist. For a container, I like to start in a solo cup with a few holes poked in the bottom for drainage. This small mass of soil is easy to water/drain, and is more than enough space for the first few weeks of your plant's life. Transplanting from a solo cup is also exceedingly easy, and minimally affects the plant.