Rent Shop Volunteer Join

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

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

Monday - September 13, 2010

From: Houston, TX
Region: Southwest
Topic: Plant Lists, Soils, Green Roofs
Title: Need Plants and Soil for a Green Roof in Buffalo, TX
Answered by: Marilyn Kircus

QUESTION:

I'm building a green roof on my cabin in the Buffalo, Texas, area. Would you know what soil and plants would be best suited for that area? I have a lot of sand I could use, but didn't know if that would sustain a grass cover.

ANSWER:

Let’s start with the question of soil first.  It should be as light as possible so you can make it as deep as possible without stressing your support system. The maximum amount of native soil that is recommended is 1/3 clean topsoil,  mixed with 1/3 compost, and 1/3 perlite or other inorganic material.  This was discussed in the FAQ’s on greenroofs.You may even want to reduce the amount of compost in the mix since the natives you'll be using don't require much organic materials in the soil.  Also it will break down over time and you will end up with less total soil. Finally, the organic material can pollute the run-off.  In this case, you would probably want more perlite and less compost. This was a recommedation of  Mark Simmons Ph.D., who is the head of green roof research at the Wildflower Center.

In a Houston, Texas experiment, the Schlindler Company’s landscape architect used a mix of 70% perlite and 30% packing peanuts and says she thinks a 50/50 mix would work just as well.  She just put the peanuts on the bottom and the perlite on the top. She added a soluble organic fertilizer once a week and got dramatically heavy growth on her plants. And the plants made a strong matrix of roots which prevented any of them from being blown over. This is  also the very lightest  soil solution.

You will have to do your own research and match the engineered  soil to your load limits. Also consider if you will have a drip irrigation system that makes it easy to add a liquid fertilizer or not, and consider the cost of various  materials.  From personal experience, I can recommend that you could also add the packing peanuts to a mix of topsoil, perlite, and compost.    I used to use peanuts in a mix to start tomatoes and the peanuts encouraged many more roots to form which helped the plants resist stress better. The peanuts seemed to work that way in this study as well. 

The Ladybird Johnson Wildflower Center is involved with research on the best plants for people in Texas to use. Sedums don’t do well here, although they are the plants of choice in other places. Here is the list of plants  recommended for green roofs. You can use various combinations of them whether you plan to have an extensive or intensive greenroof.   Click on each plant to get a full description of  it.  But be sure and use several different species to keep the entire roof  healthier and to prevent the lost of all your plants from some disease. This  information was also in the FAQ’s referenced above. You mentioned using grasses so you might want to narrow your search - see the side pannel to grasses/grass-like in the habit selection.

Here are some greenroof projects from Texas.You will have to use the search engiine to look for Texas projects as I don't get a new URL when I search. 

And for a complete discussion of building, planting, and maintainig greenroofs, see Green Roof Construction and Maintenance.  Luckett, Kelly. GreenSource Books. Mcgraw-Hill's Greensource.

 

More Green Roofs Questions

Plants for green roof in Laredo
August 22, 2008 - Hello, I am working on a green roof, and I saw your section of "Native Green Roof", and I saw good plants that I would like to use, but I am not sure if they will be suitable because of the roots (m...
view the full question and answer

Best performing species on green roofs
January 14, 2009 - Hello, I am a graduate student in Nova Scotia Canada studying native plant communities on green roofs. I have been reading about the native planted green roof at the Lady Bird Johnson Wildflower C...
view the full question and answer

Resources for a green roof project from Wayne PA
April 14, 2013 - Hello! I am researching a project to create a native wildflower/ turf mix for a green roof. I would ideally like to grow it as a sod mat, and then install it in rolls. I am currently working as an i...
view the full question and answer

Native perennial roof garden plants for New York
November 09, 2006 - I am looking for perennial roof gardens plants, sedum, hen and chickens, native plants. I am in zone six. They will have three inches of perilite, gravel, and compost. Can you give me a good local so...
view the full question and answer

Can you grow wildflowers on a Zoysia greenroof?
June 09, 2015 - I have a 700 square foot zoysia grass roof with irrigation on a pool cabana that I would like to sprinkle with wildflower seeds (bluebonnets, indian paintbrush etc) Is this possible? What is the best ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.