The simple answer is: Transplant
tress when they are DORMANT. But let's elaborate on that
answer a little bit...
B&B trees dug in Spring
DECIDUOUS TREES (those
with leaves that fall off in the winter) are best transplanted when
they have no leaves on them, which translates into late fall
and early spring. However, some trees (see list below) are best
transplanted only in the spring of the year.
transplanted in the Spring while they are dormant
EVERGREEN TREES are
quite similar when it comes to the best time to transplant them.
Basically, when they are not actively growing. One difference
between evergreens and their leafy brothers and sisters is that
evergreens can be transplanted earlier in the fall, once their new
growth has 'hardened off" (September in the midwest and northeastern
So that should answer the question.
But let's look at the reverse of that question as well...
"When is the worst time to transplant trees?" That
answer is late spring and early summer as trees are growing and
putting on their tender new growth. In other words, when they are
not dormant, and actively growing.