Well I see no one is reading the postings in a timely manner, so I will reply as a novice, I am no expert but I did read just last night on mountainmaples.com that if your trees leaf out and there is a freeze you must cover them well and some trees need more watching then others. So if a little scratch does not show green they may be gone. If green you maybe OK. Zone 5 last frost date is in May, you have a ways to go. Were these grafts sounds like they were not. I have some question to post but no one is replying so I bought a big book on maples. I wrapped all my maples in February with cotton duck and then wrapped aluminum foil around that to slow the sap. It worked well, I am seeing some tree just stating to leaf now and it has been in the mid 80s here already. Seedling may need a incubator or be in a cold frame, If I had good seedlings I would drop them in a cold frame for sure. Not to force them but to slow them. I went so far last winter that on a few warm days in February I dumped several big bags of ice on the ground around the trees.

Being obvious that you live in Bloominton Il the last average frost date is around ..apr 25th...but I think we are past it now other than just a possible mild one but who knows ... As far as your plants ... according to your post...the seedlings that did not leaf out early are also not now... theoretically containers should stay warmer thus the early leafing...unless it was a really hard freeze they should come back ...but with all of yours doing nothing I would say ...again w/o seeing them...they are toast ....ALL of my jm's started breaking buds only about 10 days ago and are just now beginning to leaf out and I'm only 60 miles south of you and NONE are potted.... all in the ground and survived the winter well with NO die back ...BUT it was a really mild winter...so I don't know whats up with your seedlings...which tend to be hardier than all of my grafted ones ...but I am NOT optimistic...since they are seedlings hopefully you paid little for them ( as they should have been cheap!!) or started them from seeds youself and are only out the sweat labor to plant 'em...David

First off, I made a mistake - they're a mix of grafts and seedlings.

Second, I tried scratching a couple and I saw green.

Third, I asked another gardener friend what they thought. They believed my JMs may bloom late because they're only getting sun in the morning, and a few hours at that.

Fourth, while my other trees have burst their buds, none of them have fully leafed out yet.

So I guess I have some reason to be optimistic yet.

The green is a good sign ...don't know how sun effects their lateness many of mine get alot of shade and I have seen no differnce ..I'd just wait ...but if not out by first of may i wouldn't be to hopeful they ever will. All you can do is wait but since they are many differnt types, i assume, it seems odd none are doing anything..David