En EspaŅol

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?

Share

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
 
rate this answer
1 rating

Sunday - November 23, 2008

From: Houston, TX
Region: Southwest
Topic: Soils, Green Roofs
Title: Soil mixes for green roofs
Answered by: Nan Hampton

QUESTION:

We are trying to set up a green roof system on our own. What do you suggest for soil? It seems the soils are proprietary and unavailable to individuals.

ANSWER:

Mark Simmons, Ecologist at the Lady Bird Wildflower Center, suggests the following recipe:  50% expanded clay, shale, or perlite; 30% decomposed granite; and 20% rice husks or another fine, slowly-degradable organic matter.  There are other mixtures that also work. For the Seattle City Hall green roof the "Roof Garden Soil Mix was: "55% PermaTill 5/16" Expanded Slate or equal, 30% USGA Root Zone Sand, and 15% Approved Compost."  Greenroofs.com suggests a mix of "1/3 clean topsoil, 1/3 compost, and 1/3 perlite or other inorganic material"  for an economical option, but this has the potential for being heavier than some other mixes.  

If you visit the Greenroofs.com directory page and choose the category "Suppliers>Individual Components>Growth Media", you will find a list of companies that sell soil mixes for green roofs.  I checked one, ERTH Products, that advertised "ERTH-HydRock Lightweight Structural Soil" described as "an engineered soil designed to be lightweight for use on structural conditions such as roof top gardens." Another company, Permatill, offers "Green Roof Planting Media".  There are more companies listed under the "Growth Media" category.  Also, you can find more information about green roof soils by Googling "green roof soil".

 

More Soils Questions

Non-blooming yuccas in Brooklyn CT
July 14, 2013 - I have outdoor yucca plants that don't flower - - in full sun. Why?
view the full question and answer

Seeding the banks of a large pond
October 18, 2011 - I have a 2 acre surface pond that is mostly a hard clay bank all around. The water level is way down and I will begin filling it very soon. I need to somehow being affordable, plant something or thing...
view the full question and answer

Failure to thrive of Hamelia patens in Laredo
September 19, 2008 - I have a question regarding Hamelias patens(firebush)that I have been trying to grow for 2 years. I live in Laredo, Texas and this area should be an excellent climate for this plant. I planted 12 of t...
view the full question and answer

Shade tolerant plants for Waynesville MO
April 09, 2013 - We moved to Waynesville, MO (gardening region 6) and when we bought our house there was a nice looking gardening area in front of the house. It is shaded moderately by a Redwood Tree and was "occupie...
view the full question and answer

Season to plant Pacific Wax Myrtle from Fallbrook CA
July 25, 2013 - Would like to know which season would be the best to plant Pacific Wax Myrtle in Fallbrook, CA area? I presently have invading bamboo, which I want to get rid of. Thank you!
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2015 Lady Bird Johnson Wildflower Center