En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer
Not Yet Rated

Wednesday - July 13, 2011

From: Austin, TX
Region: Southwest
Topic: Compost and Mulch, Watering
Title: Possibility of hydrophobic soil in Austin, TX.
Answered by: Jimmy Mills


I believe I have an area in my garden with “hydrophobic soil”: no matter how much or how slowly I water, it just beads up and rolls off and the soil beneath remains cement dry and powdery. In my reading on the internet, it suggests using a very dilute solution of soapy water (1 tsp soap to 5 gallons of water), to decrease the surface tension, but it seems this is only a temporary fix for the next watering. I also read that bagged bark mulches can be the cause (I have been using bagged native Texas bark for several years. What are your thoughts?


I must admit that I hadn’t heard of “hydrophobic soil” until I read your question and started looking on the web for an answer. How large an area are we looking at? This may influence the remedy that you choose.

Lets start by looking at soil in general. This article from Bachman’s Gardens gives a good overview of the nature of soil, its components, and the role of soil texture (ie particle sizes) in determining its water holding capacity. Generally, sandy soils allow more percolation than soils with finer particles.

This link from the University of Florida answers the question that I had:”What is hydrophobic soil?, suggests a possible cause, and offers mulching as a remedy.

A link from treesfoundation.org  (starting with the third paragraph) describes how hydrophobic soils can be the result of wildfires.

One possible remedy for hydrophobic soils is the use of non-ionic surfactants on the soil (University of North Carolina).

This forum from Gardenweb.com has comments from those who prefer the use of surfactants (soapy water) as well as those who propose changing the texture of the soil eg. adding mulch or compost and spading in the organic material.

I am partial to the latter, depending on the size of your garden plot.

Another source of information is the folks at the Travis County Office  of AgriLife Extension.


More Compost and Mulch Questions

Combining native shrubs for hedge in Austin
April 15, 2009 - Smarty, Please tell me what the definitions are for all the various water, soil moisture, drainage and light requirements mean. Are the definitions global? I live in Central East Austin and inten...
view the full question and answer

What will grow in red clay in Conroe TX?
April 10, 2011 - We just built a new home and the foundation was poured on red clay which is what my flowerbed area is in. Could you please tell me what can be planted that will grow. I am looking for ground cover, fl...
view the full question and answer

Live oak leaves turning yellow after planting in Houston
December 19, 2011 - We bought a 65 gallon live oak in early October, and have been watering fairly heavily three days a week. It seemed OK, then all of a sudden lots of the leaves are turning yellow. Is it getting too ...
view the full question and answer

Problems with Texas Ash and non-native Bradford Pear in Hutto TX
January 27, 2011 - We have planted two trees in our back yard. The first one(a Bradford Pear) died and the second one (a Texas ash) doesn't look like it's doing very well. Our back yard is mostly black clay about 1 f...
view the full question and answer

Ground cover for heavy dog traffic in Huntsville TX
July 23, 2010 - We have recently moved to Huntsville, TX where our backyard is very shady and has only a small patch of St. Augustine grass and the rest is a dry, sand-like soil. We also have 2 Great Danes and 2 Pugs...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center