Yellowing of Indian Hawthorne Growing in Rock Mulch Probably Iron Shortage

Iron chlorosis in Indian hawthorne due to poor soil development from lack of organic decomposition of rock mulch.

Q. Following your advice, I am planning to replace all of the stone mulch under and around the existing shrubs in my yard and replace with bark mulch from the orchard stock pile. I have been told that bark mulch attracts cock roaches. Is this your experience?

A. Wood mulch will attract quite a number of animals and foster plants that contribute to the breakdown of the mulch and roaches do contribute to that. These include mushrooms, earthworms, larvae of beetles such as grubs, gnats, and others. Mulches that decompose will attract decomposers.
Roaches tend to congregate in irrigation boxes in the landscape and these should be treated periodically for control if this is a problem. I normally tell people to keep the wood mulch a couple of feet from the foundation of the house.
Rock mulch will give you a more “sterile” environment and if that is what you prefer then stick with rock mulch. There is nothing wrong with rock mulch if it is used with plants that can tolerate rock mulch such as most desert dwelling plants. However, decomposing wood mulch has many, many advantages for plants compared to rock mulch which adds nothing back to the soil and most plants will perform better with wood mulches. If you would like a copy of the benefits I can forward this information to you or any of my readers.