Crape Myrtles are easy to transplant, and have shallow root systems. Do it soon, though, before the weather warms up, and it'll get along better.

First, prep the new location, so you can plunk it straight in. Dig a new hole twice as wide as the rootball you'll be digging up, and about the same depth. Fill in the bottom of the hole with some nice compost, to a level that will put the top of your rootball a couple of inches above ground level.

Dig out the beast, taking as big a rootball as you can handle. Transport it to the new hole (dragging it on a tarp is a good way) and set it up in the new hole. Get someone to help by standing back and eyeballing the plant to make sure it's straight up and down, and the best side is exposed. Backfill around the rootball with a mix of the soil that came out of the hole, and more compost. Water it in well.

Finally, prune the top to compensate for damage to the roots.

I agree with almost everything Donn said, but I think most people have stopped following the advice to prune the top to compensate for root loss. I can't tell you anything about the studies that led people to abandon this practice, except that there were some experiments done that debunked the idea of pruning after transplanting.

It still seems logical to me to "balance" top and root, but I've stopped doing it, and have been surprised by the good results. After transplanting - even with significant loss of soil around the roots - I just make sure to protect the plant from sun and wind, and I keep watering frequently and deeply until the plant is re-established. I've moved many plants this way in the past 3 years, wilting and leaf-drop notwithstanding, and won't go back to pruning unless I read about demonstated advantages to doing so.

Thanks to both of you for the advice! Donn, it *was* easy to move! And I didn't prune the top, mostly because I'm trying to encourage the "tree" shape and don't want lots of big clusters of flowers making it shrubby looking. We'll see how it goes in a few months. Thanks again!

An interesting page about compensatory pruning (to prune in order to compensate root loss) :

http://www.mntca.org/Reference_manual/compensatory-pruning.htm

Thanks, Olivier - that article was really helpful.