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No these are dawn redwoods. I think they avg 30 to 50 ft. They're only about knee height right now. How big of a hole are you thinking? 5 ft dia 2ft deep? Also do I not have to worry about frost damage? I was think of building a box to put over them. Put on the evening take off in the morning?
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Dawn Redwoods can get relatively large. And they're wide trees, so give them plenty of room wherever you plant them so they can become the really awesome trees they're meant to be.
If the trees are planted properly, then no, I would not try to protect them from frost.
Consider that idea a little more deeply and I think it will make sense to you.
These trees are hardy in Kentucky. In their real life, without you interfering, they will lose their leaves and go dormant in fall, live through the winter (as long as it's a normal winter) and leaf out again in spring.
If you coddle the tree, you reduce the trees ability to adapt to really cold temperatures. You can't save the tree from extreme cold--and it WILL get extremely cold at least a few days a year here. I don't think you plan to keep it warm every night and uncover it every morning all the way through the winter, right? And if you do that, what happens next winter?
Letting the tree go through its natural cycle (once again as long as it's planted properly and mulched) is the best thing for the tree.
MIGHT you lose the tree?
Yes. You might.
But you might lose the tree no matter what you do.
A tree hardy in zone 6 will survive in zone 6 unless something else is wrong.
The ONE exception I can think of is if you dug a tree in Georgia this summer and brought it here. That tree probably won't survive anyway. It might, but odds are against it. It does not have the genetic background to be hardy here.
The best thing you can do for them is to get them in their final growing place as quickly as possible, and do a good job planting them. Make sure they're not where the roots will be wet without draining. Make sure they don't get planted and then have no water for the next four weeks.
With regard to hole size...I need to know what the trees are in now. Are they in containers? B&B? Bare root? Or what? If they're in containers, what size? If they're B&B, how big is the root ball? If they're bare root, those roots do NOT need to get bitten by frost. But I'm assuming you have them somewhat underground.
Go to Gardenweb and look up tree planting advice. "Best way to plant a tree" or something. You'll get good advice.
Also, KNOW your tree. Spend an evening reading about what kind of planting site is needed for the kind of trees you want to plant.