Zone 6 is the lowest zone where routine fall planting is feasible; this is a largish specimen of a type that is not northern adapted, won't shut down in fall until forced into it by cold. So waiting until end of winter/early spring (after winter cold but before spring bud break) may be best in this instance.

Ideally executed fall planting catches the tree right after winter stem buds have set, so that any roots that have not been cut by the transplanting operation will then extend into the soil of the new planting site. But crape myrtles are built for warm temperate and subtropical climates, where a prompt response to autumnal conditions (in preparation for a regular, distinct and cold winter) may not be required.

This post was edited by bboy on Thu, Oct 2, 14 at 13:51

These are almost perennials in my zone six. That must be what they mean by hardy. Every one I have transplanted in fall has died back to the ground that winter.

I moved a six foot bushy one to a more sheltered location. What a waste of time. It still died back a couple years after the move. AND I spent all afternoon moving something which I could have bought new for $30.

Next time I might try to root one.

I am in south Jersey close to Philly, so it is in southern Zone 6. With global warming, it is more like Zone 7 and more and more crape myrtle are planted in my area. The last time I saw died back of crape myrtle from winter cold in my area was almost two decades ago.

So is it safer to transplant in late winter or early spring before budding out?

Safer in Spring before budding out. I'd do it in early to mid April.

If you want to preserve the trunks yes moving in early spring is probably best.
However, with a CM that big, especially on sandy S NJ soil, you're going to have a gigantic root system. Whether you move it in spring or fall, there's a chance the top of the plant will be stressed enough for some dieback if you don't do it correctly and don't provide adequate after care. In fact, if I had a choice of using a huge tree spade now, or a bunch of shovels and axes in spring, I'd probably take the former.

This post was edited by davidrt28 on Fri, Oct 3, 14 at 12:33

I see tornado's second paragraph now (sorry, I suppose I need to stop doing that - sometimes I respond to the OP first & then read responses) and that corroborates what I said. If it isn't happy with the transplantation, problems could show up even the following year.

This post was edited by davidrt28 on Fri, Oct 3, 14 at 12:32

The way to conserve roots of a transplant is to bare-root it, working carefully to get as much root as possible in the process. Arbitrarily cutting it out of the ground with a tree spade is as likely to leave behind a large proportion of roots as is using a hand spade, there is no point in producing and handling a massively heavy soil ball if the roots are cut way back in the process.

And if a tree spade dug hole is used to re-plant the spade dug tree quick re-establishment is not encouraged as the cut root ends will be left pressed against compressed hole walls. New roots respond to loosened, aerated soil rather than compacted soil, a back hoe should be used to dig planting holes for spade dug trees, with hand shovels being used to refill them.

"there is no point in producing and handling a massively heavy soil ball if the roots are cut way back in the process."

Yes, that's why this doesn't happen with a large enough tree spade! They don't get cut "way back".
Sorry bboy, all of the extremely 'heavy duty' tree moving companies use huge tree spades, not manually digging out the roots. It just isn't feasible or deserable at a certain point. Granted, more applicable to a 30' Elm than a 10-14' crape myrtle, but still. I don't think many people OR landscapers have the patience and technique to properly move either w/o specialized equipment.

Isn't root pruning still considered a good practice for transplanting a tree of this size when you have the time and flexibility? Believe the idea is to reestablish some new feeder roots within the zone that will eventually be moved with the tree. If so, seems it would be better to root prune now and move next spring or fall.

Because it is a CM, you'll likely be dealing with many suckers when/wherever you cut the roots.

Here is a link that might be useful: Root Pruning in Transplanting or Moving Trees...

If the spade were ever big enough to get most of the roots the top would be this little thing sitting in the middle. That's what nobody is ever going to do, use a spade big enough to get most of the roots.

The theory behind pruning roots in advance of transplanting depends on all the new little roots that grew out from the advance cuts being conserved during the final digging. Most of the time probably better to cut the roots once.

Bboy, Absolutely agree if there's no way to eventually move the plant without damaging (cutting) the new feeders created by pruning, then it makes no sense to waste time or effort on root pruning. Though was uncertain what you meant in your first paragraph.

Pre-transplant root pruning only affects roots within a foot or so of the surface; a depth reachable by many garden spades (or by shallow trenching where roots are too large for a garden spade to cut through). The key seems to be whether the tree/truck spade will be the right size or labor will have the know how to capture the new feeders with little or no damage when the root ball is eventually dug and moved.

The shrubs we root prune seem to adapt better than those we don't, but all these have been under 7ft - most much smaller. Do suspect it becomes less practical to pull off on larger plants, just thought it something else to consider if concerned about transplant die-back.