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
1 rating

Friday - August 01, 2008

From: Bozeman, MT
Region: Rocky Mountain
Topic: Invasive Plants
Title: Wild mustard growing in disturbed ground in Montana
Answered by: Barbara Medford

QUESTION:

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 the wildflowers. And lots of them! Do I need to weed out the mustard plants this year? Or will they die back naturally and the wildflowers will take over next year? Will they compete with the wildflowers for moisture and light? Do I need to even worry about mustard plant invading my beautiful wildflowers? Thanks-

ANSWER:

First of all, it took us a while to discover just what plant wild mustard is. There are so many common names and synonyms for it that it was very confusing. However, we finally established that Sinapis arvensis is the common weed that is most likely infesting your garden. The first thing we want to say is YES, get rid of the mustard plants and do it quickly, because now is the time they are seeding out. They are very difficult to get rid of because they have establish a long-lived seed bank of their own. Pull them out and dispose of them so that their seeds will not spread. Apparently, they generally only show up in disturbed ground, as you pointed out, but although they are native to the Meditteranean area, they now show up all over the world, and appear in all states of the United States, including Hawaii and Alaska. They are classified as a noxious invasive in several western states. They are said to be poisonous to livestock once their seedpods are formed. Many of them harbor an eelworm that attacks other crops, therefore it is best not to grow them in a garden setting. In a word, they've got to go.

Wild mustard is considered a winter annual, which means it will bloom and seed in cool weather, but in Montana, it may very well do so in the Summer. See this website from the University of Missouri Extension on wild mustard.

The wild mustard not only will shade out and crowd out your other plants, but their seed distribution will only make the problem worse. They will not "die back naturally". They are annuals just as most of your wildflowers are, but you need to stop them before they seed. They are not altogether unattractive and if a few get by you and bloom next year, that's not a disaster. But don't let them seed.

Images of Sinapis arvensis.

 

More Invasive Plants Questions

Why is Asphodelus fistulosus (onionweed) forbidden by property owners assoications?
May 14, 2009 - Our local property owners association is imploring us to remove all onionweed (Asphodelus fistulosus L.). The USDA lists it as a noxious weed. Why? I think it is pretty and flowery. Is it poison...
view the full question and answer

Native alternatives for invasive species
April 05, 2011 - I'm a native plant landscape designer in central Texas, and know our plants well. Still looking for any help I can get on replacements for Asian jasmine, English ivy, Nandina, and Red tipped photin...
view the full question and answer

Controlling Straggler Daisy
July 07, 2011 - Is there a barrier I can use that will keep Straggler Daisy under control so that I will not be a problem for my neighbors?
view the full question and answer

Invasiveness of Oenothera speciosa?
October 02, 2015 - Hello! I received a large package of Oenothera speciosa seeds and would like to plant them this month. I've read elsewhere that they can choke out out other plants and am wondering to what degree thi...
view the full question and answer

Chinaberry trees coming up volunteer
October 14, 2007 - I have several chinaberry trees that have sprouted after my neighbor trimmed his tree. I have cut these trees down to the ground a couple of times, but they just send out new shoots. Any idea on how...
view the full question and answer

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