Sometimes if you wait a week or two, the seedlings are sturdy enough to be separated, David. I use a pair of chop sticks with small, round ends to gently pull them apart.
Coleus are pretty lusty plants, but as XiaoLong says, it sure would be better if you can separate them. I recently yanked a handful of seedlings all in a clump out of my garden, wrapped them in paper towel and brought them with me to my daughter's house in Utah. Here, I pulled them apart with chop sticks and potted them each separately last week. They all survived and are now growing happily. I'm going home tomorrow, so we'll see if these kids (with a toddler and new baby) will be able to keep them alive until I return.
