Rose of Sharon is a hardy hibiscus that will grow up to 15 feet tall but your seedlings should go into a pot until they are three or four feet tall. They need good drainage so make sure the container has holes in the bottom and use potting soil. This shrub also loves full sun - I have one that still blooms in partial shade but the flowers are not as plentiful as they would be in full sun. Do not put the seedlings in an oversized pot. This leaves too much soil without roots and can cause root rot. Instead pot them each up in pots that are 8 to 12 inches across and move them to larger pots in a year or two when the seedlings fill the smaller pots with roots. Use a slow release plant food like Osmocote mixed into the potting soil. You may want to trade in your seedlings in a year or two with another gardener to get some shrubs that will thrive in your very wet and shady yard. Camellias, rhodies, red twig dogwood, acuba, lamiums, ferns, and brunnera are just a few of the plants that would be happy to grow in moist soil with no hot sun. Keep growing, Marianne Binetti