Explore Plants

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
    
 

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

QUESTION:

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.

ANSWER:

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)

 

 

 

 

 

More Rain Gardens Questions

Expanding clay soils near rain garden
May 11, 2009 - I want to put a rain garden in my yard in central TX (Kyle). My subdivision architectural review committee expressed concerns about the expansive clay soils becoming saturated and possibly shortening...
view the full question and answer

Plants for floodplain in Fairfield, New Jersey
March 21, 2010 - I have an easy question for you... I hope... We just moved into the floodplains of NJ in Fairfield and are interested in some plants. We would like to know what plants are best suited to grow in flood...
view the full question and answer

Grasses for moist, steep hillside in Tupelo MS
July 01, 2010 - I have a very steep bank that I have pampas grass planted in spots. It must be a natural spring in the bank because it stays very wet and runs into the street below. Can you suggest something to pla...
view the full question and answer

Plants for a bioswale in TX
February 18, 2011 - Dear Mr.Smarty Plants, What kind of plants are best suited for a bioswale in Edinburg, Texas?
view the full question and answer

Landscaping recommendations for site in Dubuque, IA
March 27, 2010 - I need a seed recommendation. Here are the variables: Location: Dubuque, IA (east Central Iowa) Soil type: Sandy to sandy and gravelly. Part is a riverbank facing east. Steep bank then flat to ...
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.