I use Styrofoam cups for transplanting seedlings and just keep increasing size for re-transplanting. Not PC but it's what I do. For starting seed I've used all kinds of things but settled on peat pots for starting and as soon as they get their true leaves, into the Styrofoam cups. Now if I'm starting tomatoes real early to get big plants to put in I will use plastic pots, (the cheap thin black ones), because they don't make big enough Styrofoam cups, (picture gallon size).
