Demonstration Rainwater Garden

The TRWA Demonstration Rainwater Garden at 2 Weeks After Planting in the Summer of 2025.

The Demonstration Rainwater Garden at the Townsend River Walk & Arboretum is designed to show homeowners a DIY nature friendly way to:

slow down rainwater runoff from gutters or other areas of the house and use it as an irrigation method as well as a water filter
virtually eliminate home water runoff being sent to storm sewers as the garden acts like a sponge
create an garden that is a focal point in a yard
provide habitat and food for birds and other animals
provide habitat and a nectar source for native pollinators
provide a larval source for butterflies and moths

The Rainwater Garden at the TRWA was placed in an area, opposite the picnic area, that has a steep hillside with rainwater runoff that was collection in a muddy bog, seemingly ideal for only mosquitos and weeds. This idea was included as part of the original TRWA Master Plan and in 2025 the project was stared and completed.

The design and positioning of the garden was done after taking several classes, rainwater garden design research and using the information from the University of Tennessee Smart Yards Program. Their outstanding publication, “Rain Gardens for Tennessee: A Homeowner’s Guide”, provided the combined expertise of Engineers, Soil Scientists, Plant Scientists, and Landscape Architects and Designers, with detailed plans that help guide us through the design and construction of the rainwater garden. This a wonderful guide for homeowners that are interested in creating a garden such as this.

The TRWA Volunteers proceeded to create this project as follows:

Initially a the area for the raingarden was fashioned into a bowl with a berm created at the one end with an overflow spillway the drains into the existing drain from the highway the drains into the Little River.

Initially a the area for the raingarden was fashioned into a bowl with a berm created at the one end with an overflow spillway the drains into the existing drain from the highway the drains into the Little River.
To further remove water from the picnic area, which is opposite the Rainwater Garden, a French drain was installed. It was installed along the sidewalk from the picnic area that then drains to the Rainwater Garden.

To further remove water from the picnic area, which is opposite the Rainwater Garden, a French drain was installed. It was installed along the sidewalk from the picnic area that then drains to the Rainwater Garden.
Much like a lasagna layers of clay, sand and mulch were added to a depth of about a foot to help create the proper environment of the plants and to absorb rain runoff.

Much like a lasagna layers of clay, sand and mulch were added to a depth of about a foot to help create the proper environment of the plants and to absorb rain runoff.
The initial plants that were used in creating the Rainwater Garden.

The initial plants that were used in creating the Rainwater Garden.
The plants were then arranged by height and width and grouped in no particular pattern but with the idea of a visual treat for the visitors to the TRWA!

The plants were then arranged by height and width and grouped in no particular pattern but with the idea of a visual treat for the visitors to the TRWA!
Our volunteers getting the plants into the ground!

Our volunteers getting the plants into the ground!
The Demonstration Rainwater Garden Immediately After Planting.
Didn't look like much then but the picture after a few weeks it was starting to show off and even some early blooming.
We put over 200 gallons of water on the garden during the first month of planting due to lack of rain.
Over the next few years the garden will be completely covered with native plants!

The Demonstration Rainwater Garden Immediately After Planting.
Didn't look like much then but the picture after a few weeks it was starting to show off and even some early blooming.
We put over 200 gallons of water on the garden during the first month of planting due to lack of rain.
Over the next few years the garden will be completely covered with native plants!
After the first 2 week of the Rainwater Garden being planted.
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After the first 2 week of the Rainwater Garden being planted.

Approximately 150 native plants were initially installed with the following characteristics:

Thrive in moist/wet soil
Thrive in sun to part shade
Plants that would serve as a food source for our native pollinators.

Below is a List of the Initial Plants Selected and Additional Information About Each Plant.

Common Name	Scientific Name	Soil Drainage	Pollinator Information and Additional Info
Great Blue Lobelia	Lobelia siphilitica	Moist, Occasionally Wet	Long probiscis pollinators: hummingbirds, butterflies, bumble bees Larval host for: Pink-Washed Looper Moth (Enigmogramma basigera), the Lobelia Dagger Moth (Acronicta lobeliae), the Greater Black-letter Dart and Red-banded Leafroller moths. Additional Info: https://plants.ces.ncsu.edu/plants/lobelia-siphilitica/
Cardinal Flower	Lobelia cardinalis	Moist, Occasionally Wet	Attracts butterflies and hummingbirds Larval Host for: Checkered White butterfly, Spicebush Swallowtail, Red Banded Leafroller moth. Additional Info: https://plants.ces.ncsu.edu/plants/lobelia-cardinalis/
Narrow Leaf Sunflower	Helianthus angustifolius	Good Drainage, Moist, Occasionally Wet	Birds consume the seeds. Attracts butterflies and supports several specialized bees. Larval Host for: Silvery Checkerspot butterfly Additional Info: https://plants.ces.ncsu.edu/plants/helianthus-angustifolius/
Blue Mistflower	Conoclinium coelestinum	Moist, Occasional Flooding	Attracts native bees, butterflies and moths. Provides abundant nectar for monarchs, swallowtails, queens, soldiers, pearl crescents, white peacocks, little yellows, and many other butterflies. Larval Host for: 13 specialist moths, including Eastern tailed-blue, hackberry emperor, American snout, and aster flowerhead caterpillar. Additional Info: https://plants.ces.ncsu.edu/plants/conoclinium-coelestinum/
New England Aster	Symphyotrichum novae-angliae	Good Drainage, Moist, Occasionally Dry	Attracts native bees, butterflies and moths. Host plant for several bee species. Larval Host for: Pearl Crescent, the Gorgone Checkerspot butterfly and the Wavy-Lined Emerald moth. Additional Info: https://plants.ces.ncsu.edu/plants/symphyotrichum-novae-angliae/
Pale Meadow Beauty	Rhexia mariana	Moist, Occasionally Wet	Attracts many pollinators especially native bees. Larval Host for: Gray Hairstreak, Additional Info: https://plants.ces.ncsu.edu/plants/rhexia-mariana/
Fox Sedge	Carex vulpinoidea	Wet	Birds and small mammals consume the achenes and use the plants for cover. Attracts Butterflies Larval Host for: Several skipper butterflies and a variety of moths. Additional Info: https://www.wildflower.org/plants/result.php?id_plant=cavu2
Gray's Sedge	Carex grayi	Moist, Occasionally Wet	Birds and small mammals consume the achenes and use the plants for cover. Attracts Butterflies Larval Host for: Several skipper butterflies and a variety of moths. Additional Info: https://plants.ces.ncsu.edu/plants/carex-grayi/
Swamp Rosemallow	Hibiscus grandiflorus	Frequent Standing Water, Occasional Flooding, Occasionally Wet	Attracts bees, butterflies and insects including beetles. The Rose Mallow Bee (Ptilothrix bombiformis) is a specialist forager for the hibiscus family. Larval Host for: Gray Hairstreak, Common Checkered-skipper, and Painted Lady butterflies. Additional Info: https://plants.ces.ncsu.edu/plants/hibiscus-grandiflorus/
Scarlet Rosemallow	Hibiscus coccineus	Moist, Occasionally Wet	Attracts hummingbirds, butterflies and other insects including beetles. The Rose Mallow Bee (Ptilothrix bombiformis) is a specialist forager for the hibiscus family. Larval Host for: Gray Hairstreak, Painted Lady, Common Checkered Skipper, and Tropical Checkered Skipper butterflies, as well as the Pearly Wood Nymph, Yellow Scallop Moth, Io Moth, and Delightful Bird-Dropping Moths. Additional Info: https://plants.ces.ncsu.edu/plants/hibiscus-coccineus/

To further enhance the hillside above the rain garden, blueberry plants and a grape arbor were installed as well as a new pollinator garden bordering the Lamar Alexander Parkway. Native Carolina Silver bells trees (Halesia carolina) were planted near the Rainwater Garden and surrounded by additional native plants. The TRWA rainwater garden will mature into a beautiful addition to the picnic area with colorful blooms, swaying grasses, bees and butterflies, and hopefully cleaner runoff into the cold, clear waters of the Little River.

Feel free to Contact Us with Questions or the need for Additional Information about the Rainwater Garden or any of our other Native Pollinator Gardens. It is important for all of us to encourage the well being and growth of all our Native Pollinators.

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Townsend River Walk & Arboretum

Nature Trail & Certified Tennessee Arboretum