Do other people in your area have CM's which flower?

The fertilizer and watering is alien to me. I suspect you are fighting an uphill battle and would love to talk about water and human habitation limits more, this has my attention though.

Test the PH of your soil near the tree. Tap water is not rain water. I don't believe CM's are fussy but if it is 99% tap fed and has been undergoing that fertilizing regimin who knows what you have going on.

Is grass natural in your area? My friends with new construction houses need to fertilize. Grass naturally grows here and we have good soil for it so I have never fertilized my ground except to grow corn. Never. My CM's get killed back darned near every winter but grow great all summer long and flower despite it so yours interest me. Check up on your lawn company and have the soil tested also I suppose. That way you can intelligently target your fertilizing regimin.

Good luck. I like CM's.

Thanks for the thought through response. pH was a slight concern of mine considering I read CMs like 5.0 to 6.5ph and will be alright up to 7. Will need to lookup some accurate pH measurement techniques.

There are a few other CM Natchez variety in the surrounding area that flower along with hundreds of other varieties. I imagine most aren't being fertilized.

Grass around here is kind of a luxury item. It certainly doesn't stay alive on its own. Its a semi-desert like climate. And most people I talk to about grasses like Tall Fescues have to fertilize 3-4 times a year.

Anyways, I will probably invest in some bone meal (high phosphorus) and apply in the fall.

Test before you invest. That way you scientifically know what is going on in your soil and can target it.

If all else fails, does San Diego have a decent botanical garden? I went to the one in Phoenix almost a decade ago. The variety of flowering plants blew my mind!

the fertilizer could definitely be the cause, has this crepe myrtle ever been in a large drought, or have been butchered? it looks relatively healthy from the pictures

We live inland so the temperatures are like 75-90 with low humidity. No mildew, fungus, etc. The tree has not ever been in a large drought or been butchered. And yes, the tree does look relatively healthy, but it stops growing in May. Other Crape Myrtles in the area are either just starting to bloom a little, or are at least constantly growing visible flower buds/shoots. The most curious part is the leaves turning from green to bronze/purple. I can't find the article anymore, but at least one talked about excessive nitrogen can cause a phosphorus deficiency. Either the soil does not have enough phosphorus (probably unlikely), or the excessive nitrogen from the lawn fertilizer has caused the root system to lock-up the phosphorus nutrient up take and is essentially imbalanced for a while. I dunno. The grass under the tree is thriving :(

That strip of grass surrounding the tree is so small I would tend to take it out and simply use mulch- doesn't even seem to be worth the trouble of mowing, etc. That would sure simplify the fertilizer regimen.

It's also mounded up fairly obviously- are you sure the root flare is about ground?

Cearbhaill, taking out the grass is definitely an option if I can't figure this out by the end of next year. I have other trees (albeit non flowering) that exist on our property, in or around the lawn which are probably being negatively influenced the same way as the crape myrtle. So it's in my best interest to solve this issue.

What do you mean by is the root flat above ground? As I follow the truck down to the ground there is a thin half inch layer of soil (which is covered by mulch) that exists above the major root system that developed off the trunk. So the roots aren't exposed, but yet aren't too deep. I've see crape myrtles in the area where you can see the base roots fully exposed in a 3 foot diameter circle around the truck before the lawn begins, and those trees thrive. And I have also seen the opposite. How could the mounding affect this situation (besides a possible water retention issue which doesn't exist in this case). Thanks for the feedback.

As you follow the trunk down with your fingers just make sure the area where the roots begin is exposed and not covered by soil or mulch- it needs air. When we mulch each year the last step is to run fingers around the entire base of each plant to ensure that air can get to the root flare.

The mounding brought this to mind only because if it is mounded after the tree has been planted it is easy to bury the root flare. And as grass grows, is mowed, over the years the soil level can increase due to thatch etc.

What was the reason for the mound? You planted this yourself, right? Was it easy digging or did you have difficulty going deeply enough? Were the roots opened up and spread out?

Agree to check the pH- that is a lot of concrete, which raises the pH due to leaching.

I really hate that the only fertilizer being used is all nitrogen. That's not good for anything, including the grass. Your lawn guys need to re-evaluate their maintenance program.

That could absolutely cause the disappointing performance of your crape myrtle. Please don't add another fertilzer to the problem. Rather, I think that the lawn fertilization should be changed in frequency and in the analysis.

I agree that it's getting too much nitrogen. Remedy that, and try adding bone meal instead.