Usually it is best to wait until fall to cut them back. I would also try to find out why the other two trunks died out. Give it a little plant food while you're investigating to help it out. You also might want to mulch around it if you haven't already, (but always pull the mulch a few inches away from the trunk.)

These are hardy trees, they come in all sorts of colors and sizes, and most grow very fast. Some people cut them to within a foot of the ground like a bush and others let them grow into a tree, (as you are doing.) I always cut mine back in the fall, and it always comes back; bigger and better!

I've also found that some trees start putting out lots of shoots near the base because they have been injured in some way. Its like a trees last-ditch effort at survival. There is a reason those two trunks died; try to find out why, and I would leave those other shoots alone until I knew for sure that the tree wasn't being threatened in some way that might kill the other, healthy, shoots.

The first thing I do in a situation like this is take a very good look at the plant, its leaves, and surroundings. Are the leaves injured or discolored? Do they have spots, etc.? Do they fall off easily? Are there carpenter ants in the tree or an ant bed nearby? Is grass at the base or is a large tree nearby, (competing for water/nutrients.) If nothing is visible, then start thinking about the soil. Is it full of rocks/clay? Is it moist all the time? Dry and cracked? Very compacted, (hard?) Sometimes certain plants cannot grow along side one another as well and there is always the possibility that your soil needs to be amended.

I hope this helps. It's where I would start. Good luck!

Thanks so much for the information. The tree looks very healthy. I imagine I starved it over the winter possibly by not watering it much and only one trunk survived? The leaves on the surviving trunk look fine with lots of new growth, as do the new ones. I've attached a picture. I have it mulched, about 2 inches deep, maybe a little less. My dirt, however, is originailly mostly clay but I've dug out about a foot deep throughout the whole bed and replaced the dirt with miracle grow tree and shrub dirt and top soil. So with that being said, I guess I should just wait until winter gets here and the tree is dormant. Thanks again.

We don't cut ours until the Spring in 8b. Please check with your local ag center when to prune them.

Yes, it sounds as if you have started it out right. It does look healthy too! Looks just like a big one, just miniature. They usually grow very fast, so it should really take off this summer.

You're right about the pruning too... I've always been told to prune in the fall here in Zone 7, and all of our neighbors do the same. I know that they put off a lot more flowers if you cut them back. We have some neighbors that use them as trees and others that use them as bushes. They're a real favorite around here.

I have a young one I planted last year that looked to be struggling a bit this spring too. Every trunk ended up sprouting leaves in its own time though; now its flourishing. I just treated it with a bit of insecticide/herbicide. The carpenter ants move in quickly here in SW Tennessee and they can kill even an old tree in just a few seasons!

Here's a useful link from Clemson Extension.

Some other links on the same parent site:
HGIC 1008 Crape Myrtle
HGIC 1023 Crape Myrtle Varieties

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

They don't want alot of fertilizer. They can survive with rain water only.

Please don't "top" your crape myrtle. That's called "crape murder" and it will never look good. Lots of landscapers and some homeowners do this, and it's really sad.

You can prune it any time, but I suggest you wait until those little branches grow, so you can decide which ones to keep to make an attractive multiple trunked tree. You'll know by fall, then you can remove one or two. Pruning at certain times is recommended so you don't interfere with the bloom cycle. Tip pruning to remove spent blooms and seed pods is about all they need, unless you want to remove branches totally.

This post was edited by eahamel on Tue, May 21, 13 at 17:57

Mine get full sun all day and never get any watering except for the rain, the smallest one was about that size when we moved in two years ago and it's taller than me now. The other two are huge. I never prune anything unless it took damage from a storm. They each send up new shoots all the time in the spring and I just leave them all and let the tree figure it out. Yours looks like it will do just fine I'd just let it do it's thing.

Maybe possibly too much water over winter. As I never water mine even during growing season and mine don't even have mulch around them lol. They're pretty tough, I stuck a branch in the ground a few months ago that has rooted and is growing now and it hasn't been watered except for the initial watering.