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| Lilac leaf Photo by Vicky Vahling |
I have lived in my house for 20 years and have never really spent any time maintaining my Lilac bush. This spring I pruned all the dead branches out and dug out all the new suckers that had started to get out of hand. The Lilac bush looked great and was really starting to flourish until the middle of summer when the leaves started turning yellow on all the new growth with the leaf veins staying green. Then the leaves started to turn brown around the edges and began dropping from the plant.
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| Lilac leaves Photo: Vicky Vahling |
First, I made sure that I hadn’t over watered it and dug a
hole twelve inches deep about two feet away from the base of the bush. There
was no pooling of water so that told me that it was not being over watered. I
started doing research on the CSU Extension website that led me to believe that
my Lilac bush had iron chlorosis. “Chlorosis” means “lack of iron.” One of the
main causes of lack of iron is a high pH level of the soil. High pH reduces iron
availability. Colorado soils are generally high in iron, however the soils are
mostly alkaline causing most of the iron to be in an insoluble form not usable
to plants.
I purchased a liquid iron chelate and followed the instructions on the bottle. It recommended 10 tablespoons per gallon of water and to use four gallons for a four to five foot plant. I dug four holes about six inches deep and two feet out from the base of the plant and poured in the solution. You can also dig a type of trench around the bush and pour the iron solution into the trench. A preventative way of helping your plants before they get iron chlorosis is with an iron spray. Using iron sprays should be done in cooler weather, preferably during spring and not during the heat of the summer. You must be careful when using an iron spray because it will stain sidewalks and other surfaces red.
I’ve had no other trouble with any of my other plants or trees, but this lilac bush is in a location all by itself in the back of the yard. Maple, oak and aspen are just a few of the locally used trees that can develop iron chlorosis. Since I have quite a bit of iron chelate remaining I’m going to wait until next spring and spray the bushes to help prevent this happening again.
CSU has several sources for more information about iron chlorosis here: