En EspaŅol

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?


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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
6 ratings

Wednesday - July 22, 2009

From: Baltimore, MD
Region: Mid-Atlantic
Topic: Rain Gardens, Compost and Mulch, Grasses or Grass-like
Title: Native plants for a bioswale in Baltimore
Answered by: Barbara Medford


What native plants would suit a bioswale in an urban part of Baltimore City? The clay soil gets waterlogged and the site has part shade.


Mr. Smarty Plants is not THAT smart, and can always learn something new. This time we learned about bioswales. Common swales are typically vegetated with turf grass and are a conveyance tool, basically a grassy stormwater sewer that conveys water as quickly as possible from Point A to Point B. A bioswale differs in that the turf grass is replaced with native prairie vegetation. This will significantly reduce the flow velocity (slow down of the runoff) in the swale’s drainage course. The residence time of the runoff is thus increased, which gives it the time to be stored, filtered, and infiltrated. These processes remove pollutants and suspended solids from runoff.

In terms of your clay soil, we found this information on bioswale construction from the USDA, which shows compost tilled into the native soil (clay, in this instance) to facilitate the drainage. The plants we have selected are all perennial, tolerate shade, and will grow in moist, clay soils. These are plants with fibrous roots that will hold in the soil when water is rushing by, help to slow it down, and permit the pollutants in the water to be filtered out. 

Since our suggestions are basically for prairie grasses, you might be interested in reading our How-To Article Recreating a Prairie, which has instructions for time of year to be planting, preparing the soil, planting and caring for the grasses. When you are ready to begin, go to our Native Plant Suppliers section, put your town and state in the Enter Search Location box, and you will get a list of native plant nurseries, seed companies and landscape consultants in your general area who can help you select the right plants for your purpose.

Andropogon gerardii (big bluestem)

Carex blanda (eastern woodland sedge)

Carex hystericina (bottlebrush sedge)

Carex texensis (Texas sedge)

Chasmanthium latifolium (Inland sea oats)

Elymus canadensis (Canada wildrye)

Elymus virginicus (Virginia wildrye)

Sorghastrum nutans (Indiangrass)

Andropogon gerardii

Carex blanda

Carex hystericina

Carex texensis

Chasmanthium latifolium

Elymus canadensis

Elymus virginicus

Sorghastrum nutans






More Grasses or Grass-like Questions

Need help fighting grass burs in La Grange, TX.
January 22, 2013 - I have 4 acres of wildflowers planted in my front yard. Unfortunately, grassburs have crept in & I need to control them with a pre-emergent. Will this keep the wildflowers from blooming? Also, would l...
view the full question and answer

Failure to bloom of gulf muhly in Dripping Springs TX
April 19, 2010 - I have had several gulf muhly in my garden for about 8 years, but last fall they did not bloom, however several others only feet away did. Do you have any idea why this might have occurred?
view the full question and answer

Plants for bioswale in Vero Beach FL
September 28, 2009 - Can you recommend plantings for bioswales located in Volusia County area of Florida?
view the full question and answer

Dying non-native St. Augustine grass from Austin
May 02, 2013 - Although we all know St. Augustine grass is not a good thing, I am stuck with it and am trying to save areas that appear to have take-all fungus. I have done much reading online and have tried peat m...
view the full question and answer

Erosion at edge of driveway in Abilene TX
August 26, 2011 - My lawn suffered a great loss of grass over the winter and the soil at the edge of the driveway is washing away with watering and the occasional rains that we have. I am trying to get the grass to gr...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
© 2015 Lady Bird Johnson Wildflower Center