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
Not Yet Rated

Monday - May 14, 2012

From: San Antonio, TX
Region: Southwest
Topic: Invasive Plants, Herbs/Forbs
Title: Invasive American Germander from San Antonio
Answered by: Barbara Medford

QUESTION:

I brought home some American Germander (Teucruim canadense) - page 259 In Wildflowers of Texas by Geyata Ajilvsgi - from a railroad right-of-way. Since it is a member of the mint family it has become super invasive in my wildflower garden. I have tried solarization, Roundup, tilling and mulching to kill it but none of these methods have been successful. Do you have any suggestions? Maybe Ornamec?

ANSWER:

We have probably mentioned this before, but the best way to control invasives is to never plant them. Because Teucrium canadense (Canada germander) is a member of the Lamiaceae (mint) family it is unusually invasive. You can see from this USDA Plant Profile map that it is indeed native to Bexar County and to a whole lot of the surrounding area.

We did some research on the herbicide Ornamec, and discovered that it is a grass killing herbicide. In other words, it will kill monocot plants, grasses, and not touch dicots, or broad-leaved plants. So you would add a toxic material to your garden soil that would not faze the germander at all. Always research the specific purposes of a herbicide before you purchase or apply it.

We learned that the Teucrium canadense spreads by underground rhizomes, so that even an appropriate herbicide would probably not be able to get to those rhizomes. We also learned that it appears to be a wetland plant. If you have wildflowers native to the Bexar county area, you could probably water them less and at least discourage the germander. However, you also need to get down and root out those rhizomes, getting the tubers that store food for the plant and ensure its safety from the herbicides. There is no quick solution to a plant that can protect itself this easily. Of course, you should always cut down the plant before it has a chance to bloom and seed, as that is another way it spreads.

If worse comes to worse, you can try the paintbrush and herbicide method. Get a small amount of undiluted herbicide, the kind for dicots or broad leaf plants and some small disposable sponge paintbrushes. Full disclosure: This is hands and knees work and not easy. One at a time, clip the stem of the germander as close to the earth as possible. Then, within 5 minutes, paint the cut edge with the herbicide. You need to do it quickly because the plant will try to heal the cut over to protect the very rhizomes you are trying to kill. And keep pulling them out, digging out the rhizomes.

Next time you see some wildflowers in a wild situation, step away from the plant.

 

From the Image Gallery


American germander
Teucrium canadense

American germander
Teucrium canadense

American germander
Teucrium canadense

More Herbs/Forbs Questions

Evergreen plant to cover parents' graves in Louisiana
June 30, 2013 - We want to plant ground cover on our parents graves in Plain Dealing Cemetery in north Bossier Parish LA. Soil is red clay/dirt. Want native plant, slow growing, short not tall plant, that might sta...
view the full question and answer

Garden instructions from Austin
June 12, 2013 - I'm a beginning gardener putting in some new landscaping in my front yard in north central Austin, TX. The yard faces almost due east, so it gets full sun until early afternoon, when the house's sha...
view the full question and answer

Plant Suggestions for Flower Boxes in NY
July 06, 2016 - I am doing a project for a friend that had some flower boxes built along his driveway. They are along a hill leading up to his porch. They are made of all wood and have a wooden wall along the not-hil...
view the full question and answer

Dying blackeyed Susans in new garden in Pennsylvania
August 26, 2008 - Hi Mr. Smarty Plants! I have recently planted black eyed susans in a newly dug garden along with some cone flowers. The other flowers are doing fine but the black eyed susans have all dried up and are...
view the full question and answer

Fertilizer amounts for native perennials in Belton, TX
March 18, 2009 - I am a novice gardener and need advice on how to fertilize my native perennials. I would like to use organic fertilizer and need advice on exactly what to use. I have a compost pile but it does not ...
view the full question and answer

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