Q. We are planning on removing our lawn and changing over to desert landscaping but after reading your blog I am wondering how the old, large Modesto Ash trees will fare from this change? Do you think it would be an issue? I tried to find out about their root system, it seems like it is shallow, but won’t that be an issue as the roots will be damaged and then covered with hot rocks? See this posting on my blog: http://xtremehorticulture.blogspot.com/2015/08/converting-to-desert-landscapes-can.html Large tree suffering die back due to drought after conversion to desert landscaping A. I am not telling you not to convert to desert landscaping but be cognizant that established trees can get hurt in the process and many landscapers do not know how to convert from lawns to desert landscaping with existing large trees.  If you have large trees in an established landscape you have some options.  1. Leave the lawn surrounding the big trees and remove lawn where there are no big trees.  2. Remove lawn and spiral in-line drip tubing around the existing trees out to a distance of their drip line (spread). However, if you do this you should put this drip tubing on a separate valve and run it longer and less often than drip going to other plants.  3. Put LOTS of plants beneath these large trees and drip irrigate them to assist the existing trees with enough water. This is above and beyond having emitters for the large trees, too.  4. Use a lawn irrigation valve to feed bubblers to existing trees and form a basin around the trees to capture water from the bubblers. This is called basin/bubbler irrigation and is a form of flood or border irrigation. The basins must be level and flat and be three to four inches thick.