Foliar fertilization good for flowering woody plants
Question: We have a crape myrtle tree in our southwest back yard. It gets plenty of water, and I fertilized it last month with some Miracle-Gro flowering fertilizer. At the time, there were some burned edges on some of the leaves and some yellowing. Now it is really burned on the edges of all of the leaves with yellowing. HELP!
A couple of things on your crape myrtle: I have kept crape myrtle growing in raw desert soil in good shape for 20 years at the UNCE Orchard at UNLV’s Center for Urban Horticulture and Water Conservation, 4734 Horse Drive. I used a combination of a general purpose tree and shrub fertilizer (16-16-16) plus an iron application combined with foliar sprays of Miracle-Gro.
I don’t really endorse products, but Miracle-Gro is the one I used and have found to work just fine. You could just as easily use a different good quality foliar fertilizer for flowering woody plants. I apply the granular 16-16-16 in late January or early February using about 2 pounds of fertilizer applied to the surface of the soil and watered into the roots without it washing against the trunk.
You can make some shallow holes in multiple places under the canopy and water it in thoroughly. At the same time, I also apply an iron chelate, iron EDDHA at the rate of a tablespoon or two scattered in the same holes and watered in so that none of it remains on the soil surface. It is light-sensitive.
After about one month of new growth, I then foliar fertilize the tree with a Miracle-Gro spray or comparable product. I do both of these annually. You can do the same thing (except for the iron) by using a fairly large quantity of good quality compost annually. My guess is that you either are missing the iron application, watering too often or not watering deeply when you do water.
Bob Morris is a professor emeritus in horticulture with the University of Nevada and can be reached at extremehort@aol.com. Visit his blog at xtremehorticulture.blogspot.com.