Best time to move a tree is while it is dormant. Most nurseries
recommend December or January, although you can sometimes stretch this
to mid-November through mid-February. After that, you chances of
success diminish considerably.

bryan lafleur wrote:

Have a 12' Japanese Maple, a wedding gift we planted 30 months ago,
which we want to move from our old to our new home.



This is a terrible time to move an established plant, especially trees
on the mature side. But if you are moving now and it has obvious
sentimental value, not much choice. With the right equipment and care
it might make it.

Good luck,
Bryan