Planted many varieties of apple trees on my property this year. The weather has turned cold below freezing and in the low 20's for days at a time. Half of the trees have lost their leaves and went dormant. The other half still has leaves on them that are green.   Anyone have any idea what is going on here??? Should I be worried about these trees not going dorment yet??

Apple trees survive the winter just fine without human worry or interference.

Mine take a long time to drop their leaves, too. They've made it through the winter just fine--I think apples just take longer to drop their leaves than other trees. Some of mine still have their leaves despite freezing night temps, and even a few days of snow. Keep an eye on them if/when it snows, though, because the leaves will hold more snow than bare branches, and they might get weighed down and break under the weight of the snow. I lost a young tree last year because the snow was too heavy and tipped it over.

maybe you have just developed some zone 2 apples. But I wouldn't worry too much as long as they get their 400hrs of chill hours they should fruit when the spring/summer comes along

Randy,  The trees I grafted last spring and planted out this fall also still have their leaves, but hoping that is normal for new trees.  Even my 50 year old Norway Maple still has its leaves, much longer than it has in years past   Bill  

My apple trees stay green year round.  I'm in zone 10b, so we get maybe 200 to 250 chill hours a year --- not even close to the recommended 300 to 400 hours many of my trees "require" to break dormancy.  Yet they still produce.

I used to get all heroic and hand pick all the leaves off my apple trees.  I figured that it was my duty to force them into dormancy, so once Christmas was over, I'd go out there and strip them clean.  It didn't seem to make any difference --- all it did was really slow them down in spring time.  Now I just leave them alone and they do OK.  I still wish we would get a good cold snap and get them all to go dormant but it's not absolutely necessary.

My cherry trees do the same thing and it's a sign of tree health. The longer they keep their leave green through fall the healthier they are. But definitely watch out if there's a big snow.