I have several large sweet gum trees growing around the yard. Over the past 4-5 years I have dug up maybe 10 seedlings and put them in pots. They grow straight with thick trunks and have great leaves in the fall. Then in the spring the buds start to swell, and then they die. One lasted a second year, but most don't. The parent trees are obviously acclimated to the "winter" temperatures here, so I am puzzled why the seedlings don't last. There are several about a foot high out there in the yard right now, and I am trying to decide if I should dig them up or just run the lawn mower over them and forget it.

Like all my trees, they are outside most of the "winter" here, which means temperatures in the twenties (F) a total of five nights since last year, and just barely below freezing eight or ten nights.

Ideas?

"I am trying to decide if I should dig them up or just run the lawn mower over them and forget it."

Ivan, don't.
Killing trees is not good for your karma.
Besides that, once done there's no coming back, and most probably you will regret it!

Agreed completely. There is this other occupant of the house who doesn't realize that the yard is just an extension of the bonsai area and thinks that the grass should be unbroken, so that all these little trees should disappear. She doesn't seem to understand.

Always a difficult compromise...