Contact Us Host an Event 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

Wednesday - November 26, 2014

From: Austin, TX
Region: Southwest
Topic: Planting, Erosion Control, Groundcovers, Shade Tolerant, Grasses or Grass-like
Title: O.K. to grow grass under a live oak?
Answered by: Guy Thompson

QUESTION:

Is it a bad idea to plant grass around a mature live oak? We have erosion issues and trying to keep mulch in the beds around the tree groves is a challenge, even with edging. Much of the native dirt has actually washed away over the past several years when we gave up on mulch and some of the roots are starting to become exposed. A landscaper has suggested putting grass up to the trees to help with erosion. Honestly, I wouldn't mind if the tree growth slowed, but I do want them to stay healthy and disease free.

ANSWER:

Before planting anything you will need to confront the erosion problem that you have.  Perhaps you could build swales or barriers to redirect rainwater away from the oak until your new plantings take hold in some freshly added soil.

Growing grass under a live oak will not harm the tree.  The problem is finding a grass that will thrive in the tree's shade.  Hopefully you have a high canopy that allows considerable light to reach the ground.  There are no native turf grasses that do well in shade.  However, there are several bunch grasses that would look nice under light shade.  These grow too tall to stand foot traffic, but they can be quite attractive.

 One grass that I grow in shade as a ground cover is Paspalum setaceum (Thin paspalum).  It grows only a few inches high and the rather unattractive foot-tall seed heads can be controlled by mowing.  If you can accept taller species, consider the following suggestions, taken from a previous Mr. Smarty Plants answer:

 Bouteloua curtipendula (sideoats grama), the State Grass of Texas, 2-3 feet

Bouteloua hirsuta (hairy grama), 10-18 inches

Chasmanthium latifolium (Inland sea oats), 2-4 feet, a particularly attractive plant that grows well in deep shade

Elymus canadensis (Canada wildrye), 2-4 feet

Poa arachnifera (Texas bluegrass), 2-3 feet

Schizachyrium scoparium (little bluestem), 2-4 feet

You might also consider using sedges.  They make very good groundcovers and they tend to be rather short.  You can read about their use for lawns in Sedge Lawns for Every Landscape by John Greenlee.

Carex blanda (eastern woodland sedge), 1-3 feet

Carex cherokeensis (Cherokee sedge), 12-18 inches

Carex planostachys (cedar sedge), less than 12 inches

Carex texensis (Texas sedge), 10-12 inches

Finally, here are a few groundcovers that aren't grasses or grass-like, are less than 18 inches high and will grow in the shade or part shade.  They are mowable.  I attach extra images of these.

Calyptocarpus vialis (Straggler daisy)

Ruellia humilis (Fringeleaf wild petunia)

Viola affinis (Sand violet)

Seeds for many of these plants may be obtained at your local plant nurseries.  Native American Seed is a particularly good source.

 

 

 

 

From the Image Gallery


Horseherb
Calyptocarpus vialis

Prairie petunia
Ruellia humilis

Sand violet
Viola affinis

More Erosion Control Questions

Plants to stabilize a steep bank in South Carolina
January 09, 2010 - I would like to use native plantings to stabilize a steep bank. The bank is on the side of the gravel road I cut back into the woods and around a 36" pipe going under the road to allow the free flow ...
view the full question and answer

Plants for banks of a retention pond in Alabama
April 24, 2009 - What can we plant on the inner and out walls of a detention pond to stop erosion? The pond is located in a neighborhood in Mobile, AL and the walls are 9 ft high with a steep slope.
view the full question and answer

Stopping Soil Erosion on a Slope
May 13, 2013 - I live in Bonaire, GA and have a slope in my back yard. The soil is red clay and it gets sun most of the day. A small section of this slope tends to have a mudslide to the bottom of the slope. How ...
view the full question and answer

Plants for erosion control in IL
April 21, 2011 - Steep 40ft slope in rural Illinois with Sandy soil. Recently several trees slid down this slope due to wet conditions. We need any inexpensive plants to hold the hillside in check before erosion creep...
view the full question and answer

Controlling slugs in a Pacific Northwest strawberry patch
February 04, 2013 - Would love to plant various varieties of strawberries on a bank for erosion control and ground cover. How can we keep the slugs at bay? We are in the the Pacific Northwest
view the full question and answer

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