All plants can benefit from mulch or compost to help prevent the top layer of dirt from drying out too quickly. You can start your own compost pile, to use later, but in the meantime go buy a big bag of compost from your garden center. The size of your seedlings will determine the depth of the compost you use - perhaps just start with an inch or so if the seedlings are tiny. It's important to keep some kind of mulch/compost on the soil here in the southwest where soil temperatures can soar. Keeping the roots cool goes along way toward plants surviving through the summer.

I use organic mulch too, for the reasons cited above. Just remember to pull the mulch away from the crown of the plant to minimize rotting.