Host an Event Volunteer Join Tickets

Support the plant database you love!

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
1 rating

Saturday - July 17, 2010

From: Austin, TX
Region: Southwest
Topic: Invasive Plants
Title: Getting rid of invasive grasses in backyard
Answered by: Nan Hampton

QUESTION:

Mr. Smarty Plants, How do I rid my yard of invasive grasses? I am finding Bermuda, stickers, crabgrass and maybe even Johnson grass throughout my backyard. The invasion is substantial in one 200+ sq ft area. I haven't mowed all summer because I was letting my wildflowers go to seed. Should I use a selective herbicide? If so will it hurt the lizards and toads? At what height should I mow both that area and my Indian paintbrushes, native verbena and brown-eyed Susans? Thanks

ANSWER:

Mr. Smarty Plants is sorry to tell you that getting rid of all these invasive weeds is not going to be easy.  Just a few days ago I wrote the answer to a question about getting rid of the non-native Cynodon dactylon (bermudagrass) in a lawn.  Bermudagrass is especially difficult because it spreads by seeds, stolons (above ground stems) and by underground rhizomes.  The advice in the previous answer stands for your bermudagrass. Sorghum halepense (johnsongrass) is another non-native invasive that is able to spread by two methods similar to bermudagrass—by seeds and by underground rhizomes. 

By stickers I assume you mean sandburs.  There are several species of sandburs, but I suspect you have Cenchrus spinifex (coastal sandbur).  It is important to remove the seeds (these are within the stickerburs) before they drop to the ground.  Since this is an annual species, it must drop its seeds to come up again.  Here is more information about Cenchrus sp. from California and ways to control it. You can also dig out and pull up the plants, but the most important thing is to not let the burs fall to the ground.  Digitaria sanguinalis (tall crabgrass) or Digitaria ischaemum (small or smooth crabgrass) also reproduces by seeds so it is important to remove seed heads before they mature.  This is also important for all your invasives—don't let them go to seed!

For all the invasive species you named you will need to use multiple control measures consisting of physically removing as many plants as possible (is there a teenager in your neighborhood who needs a summer job?), making sure that all the seed heads are removed before they mature, and judiciously using herbicides (see the suggested applications in the different control articles linked above for guidance).  You will need to be persistent and diligent.  If you think that this is too daunting, you can always use solarization to kill everything and start completely over.  The Native American Seed website has a very good description of how to do this in their article, Planting Tips for Native Grasses.  Here is another take on Soil Solarization from University of California-Davis.

There is some evidence that amphibians (e.g., toads, frogs and salamanders) are negatively affected by one of the most widely used herbicides, glyphosate, and the particular surfacant that is used to carry it. The risk could be lowered by painting on the herbicide with a small brush or sponge applicator rather than by spraying it.

For mowing, you will want to wait until most of your wildflowers have set and dropped their seeds.  You might find the How to Article, Meadow Gardening, helpful for advice about maintaining your meadow-like lawn.  Also, you don't want to mow too short—leaving your grasses and wildflowers several inches high (at least 4 to 6 inches) can help control bermudagrass and crabgrass since neither plant grows as well when shaded.

Finally, the Greater Madison Healthy Lawn Team (Madison, Wisconsin) has a very good treatment of Weed Control Methods using corn gluten, homemade herbicides made from liquid soap and vinegar, and solarization.

Good luck!

 

More Invasive Plants Questions

Getting rid of King Ranch bluestem
August 13, 2008 - I have recently moved to South Texas Coastal town of Portland, Texas. My St. Augestine turf grass has been invaded by - what the neighbors tell me - King Ranch Blue Stem grass. I am having a terribl...
view the full question and answer

Damage to ruellia in Monroe LA
October 26, 2009 - I have hundreds of Ruellia Brittoniana. Dwarf Katie White, Katie Blue and Katie Pink. I am finding holes in some of the leaves, Some just have notches chewed out of them. Some of the leaves have...
view the full question and answer

Information about empress tree (Paulownia tomentosa)
March 07, 2008 - I have an Empress Tree, 3 yrs old, and the limbs grow straight out from the trunk about 2-3ft and then grow straight upward. When do they start to grow outward for a canopy??
view the full question and answer

Wild mustard growing in disturbed ground in Montana
August 01, 2008 - I have recently planted "plugs" of wildflowers in beds throughout my yard. Because the soil was disturbed, I now not only have some beautiful wildflowers growing, but also mustard plants growing in ...
view the full question and answer

Problems with recently planted trumpet vine from Worcester MA
October 20, 2012 - Dear Mr. Smarty Plants, I have a question about my recently planted Trumpet Vines. First of all, I live in Massachusetts, zone 6. The soil is perfect for the two vines, which I bought from a local nur...
view the full question and answer

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