As you allow them to grow back thin out unwanted crossing etc. stems to restore natural amount of density.

You can, if you can access the trunks at ground level, take out one or more of the stems (up to a third of them for the next 3 years) at ground level, and let replacements grow up to a natural height. Keep taking out the old trunks until you have taken them all, and they are all now the natural height. If the topping has gone on for a number of years, then it will be hard to have a natural look with the old, topping-grown knuckles there.

If you REALLY can't get at the old stems at ground level to take out individual trunks, which may well be the case, you have 2 choices - 1) take all the trunks down at ground level, let the new shoots grow up, selecting 3-7 of the stronger ones, and start over again. Or 2) take the knuckles off to where the stems are straight, select a very few of the resultant sprouts, and train them to grow up as a new canopy. The drawback to this is that there will be a noticeable difference where the cut was made, in the diameters of the trunk and branches.

It would help to know the cultivar, so the probable height can be known. If it's one that grows to 30' or more, and there is room for only 20' or less, then you may have to take them out or move them to where there is room for them to grow, replacing them with more suitable cultivars. Rejuvenation pruning of a third of the stems annually will keep the height smaller, but you won't have the muscular-looking, peeling trunks, as those only develop with age, and you aren't letting the trunks age.

I'm sure you don't want to take the large limbs to the ground, but I think doing what bboy said may be the most feasible alternative for most people. We had this one man who lived close to my house who would top huge sycamores every year. At some point (maybe 5-10 yrs ago) he stopped doing it and they are growing very well...and you cannot tell he used to top the sycamores. Its amazing how nature can quickly repair our mistakes with time...or even some of its own mistakes such as high wind damage from hurricanes.

I don't think simply not pruning the trees, like the guy with the sycamores, would result in nature correcting the aesthetics of the Crepe Myrtles (at least not for a very very long time if at all). I would recommend bboy's method in many cases, but the advise dibbit gave can work quite well. I have cut Crepe Myrtles back to near ground level and had them resprout with excellent results.

From a publication by Virginia Tech:

"Crapemyrtles that have previously been topped can, to an extent, be "untopped." Select two or three of the stronger shoots per "topping knuckle" (the knob that develops where the topping cut was made) and prune the others off. Then prune (head back) the selected shoots above outward facing buds to begin to develop a new branch pattern. The plant will never again have its true or natural crapemyrtle form, but it can be improved."

A link to the entire publication is below. Great info there.

Here is a link that might be useful: Pruning Crape Myrtles

Around here there are lots of crepe myrtles, and I've noticed that every year they are topped and every year they grow back and flower beautifully.

I have some myself, but I think the previous owners never looked after them as they are a big scragly looking.

As someone that lives in the South where this ignorant practice goes on every year, I agree with dibbit that there are some trees that will never look natural again. These trees have been topped year after year to the same place each year; they now have knots the size of a big man's fist. The sprouts that come out of these knots are spindly and weak - a hot afternoon's thunderstorm makes a real mess of them.

For those people that still don't get it, these plants WILL flower beautifully each year WITHOUT being topped. Topping is not required.

Neighbors down the street had two crepe myrtles professionally installed this fall. Beautiful plants, probably 12-15 feet tall, real specimens. They had never been topped. They got topped about a month ago. In my opinion they just ruined their investment.

As to the original question: I'd say take them to the ground all at once and let them resprout and groom them from there.

I have a similar question. I manage a number of Development tennis courts with Crepe Myrtles planted all around. Each year they lose their leaves to the point where the tennis players want all the Crepes removed. If I top them it would solve my problem and allow me to keep the trees. The other option is to chop them all. What would be the recommendation in this case?

I recently bought a new home with very old, tall oaks and about 6 crepe myrtles. The crepes are also super tall - I can barely reach the lowest blooms. But about 2/3 of the tree will bloom, I assume because the large oaks block out the sun. Can I turn my crepes into shrubs or short trees? If so, how do I do it?

Thanks for the advice brandon