Can I seal my new fence posts even if they are wet?

My husband built a treated wood picket fence gate probably 6 years ago and we didn't bother to paint it until this summer. It was fine. We use opaque white exterior stain and the rest of the fence is 14 years old now and is in great shape. Some of the parts aren't treated and they're still in good shape. (The gate is newer because the original one was an ancient one we found in the backyard that broke when a paperboy hit it with a newspaper.) We bleached the heck out of the gate before painting it.

If you used treated lumber, you shouldn't have any problems leaving it unpainted/stained for now.

Cover the tops of the posts with upside-down tin cans or something. They will stop absorbing additional water, but they will be able to dry out a bit too. (and wait to paint when the posts are dried out)

Neater than tin cans would be plastic squares or circles cut from ice cream lids or the like. One small nail will keep them in place until you can treat them with sealant.

The wood is already treated for outdoors. I like the idea of covering them now. I was wondering if that would help. Thanks.

I wouldn't use any tar-type roofing product, as it may end up running down the sides of the post when it gets heated by the sun later on. Just use the stuff they make for wooden decks. It's best to wait until the wood is dry, so that you don't trap the moisture inside.

If they're already treated, they'll be just fine over winter. In fact, it's probably best to let treated lumber weather a season or two before considering coating them with anything.