We put in a 36inch box multi-trunk Crape Myrtle Natchez 3-4 years ago. The first year it had 2-3 flowers on it. Since then there have been zero flowers.
The tree gets full sun and quite a bit of water. The tree gets watered by the stream rotor lawn sprinklers (it never really rains in San Diego) every 3 days, and at the same time gets watered by (3) 2gph emitters for 1.5 hrs.
What's interesting is that in early March the tree starts to grow leaves and new shoots and really comes alive, but then by about mid April everything shuts down. By late April the leaves on the top and west facing side of the tree start to get bronzed and the new branches are really red in color. All growth has stopped and any newly sprouting tips are gone. The tree pretty much sits at this stage until "winter" when the leaves fall off.
I think I may have identified the issue this year, but wanted some feedback. Our lawn is maintained by a crew of guys who use a slow release 24-0-0 fertilizer on the grass every few months or so. I think what ends up happening is that the grass loves the high nitrogen fertilizer and so does the crape myrtle coming out of dormancy. However the crape myrtle quickly becomes phosphorus deficient mainly because of the excess nitrogen and stops growing.
So my question besides confirming the issue, is how should I handle it this year and the years to come? I assumed I might be able to balance the nutrients this year and hit the tree and grass surrounding it with a relatively slow release 15-30-15 fertilizer a week and a half ago, but nothing seems to be changing. In hindsight I probably should have found a fertilizer with 0 nitrogen since that is probably causing the issue. What are the recommendations for the rest of the year? No more fertilizer? But what about the fertilizer that the grass needs? Kind of hard to fertilize the grass without fertilizing the tree as well. And then what about the years to come? I've read a couple different recommendations. Some say 10-10-10 fertilizer for the tree and some say 12-8-6, some say 10-15-10, etc. What I think I need is a well balanced fertilizer for both the grass and tree. What is the recommendation for the years to come? I know Crape Myrtles supposedly don't need a lot of fertilizer, but our grass does need a fair share.
ps the grass in the foreground is the neighbor's grass. the grass in the background is our grass
Thanks!
The 3 pictures attached are of green leaves that are in the shade of the other leaves/branches, leaves that are now bronze/purple/green (but were previously completely green), and the whole tree as of 5/1/2016 (which is the way it will look until fall)
