For years, the Townsend River Walk & Arboretum (TRWA) was challenged by a steep hillside on the north end of the TRWA with rainwater runoff collecting in a muddy bog, seemingly ideal for only mosquitos and weeds. To further complicate the situation with this unused area, the hillside drained from Highway 321, Lamar Alexander Parkway, with all the petroleum-based contaminants that come from a busy road eventually draining into the Little River. An impossible landscape or just the right challenge?
In 2022 the development of a strategic plan for the TRWA included installing a rain garden at the bottom of the drainage. While the strategic plan was enthusiastically adopted, other projects were already in the works, delaying the implementation of the rain garden.
In Spring 2025, the timing was just right for the rain garden project. The TRWA had successfully completed an April fundraising campaign for the adjoining picnic area and the rain water garden as well as a much needed bear-proof refuse can, dog cleanup bags and refurbished restroom area. The fundraising met its goal and more! It was time to solve the roadside and rain water run-off challenge with a rain garden!
As DIY landscapers, the TRWA volunteers turned to the experts for guidance: 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 guided us through every step of designing and installing a rain garden.
The experts at UT summarize the benefits of rain gardens that spoke directly to our unique challenges at the TRWA. Rain gardens can:
- Slow down rainwater runoff
- Decrease potential for erosion
- Improve soil quality over time
- Decrease the need for irrigation
- Provide food and shelter for native birds and pollinators
- Help improve water quality in recreational areas
- Rely on native plants to act as a natural sponge in wet areas
The TRWA volunteers worked several mornings to shape the “bowl” area to serve as the base of the rain garden, then amended the soil with alternating layers of mulch and sand to create the “sponge”. The volunteers also installed a French drain from the new picnic area and a dry creek bed to capture runoff from the hillside above and direct it into the rain garden.
Next up, was the fun of planting day, installing approximately 150 plants! The TRWA worked with local grower Miller’s Cove Native Plants for native plants that would thrive in (1) moist/wet soil, (2) sun to part shade, and (3) plants that would serve as a food source for our native pollinators.
Below is a list of plants selected and additional information about each plant.
| Common Name |
Scientific Name |
Height | Width | Spacing | Soil Drainage | Additional Info |
| Great Blue Lobelia | Lobelia siphilitica | 1.5 ft - 4 ft | 1ft - 1.5ft | 1.5ft | Moist, Occasionally Wet | https://plants.ces.ncsu.edu/plants/lobelia-siphilitica/ |
| Cardinal Flower | Lobelia cardinalis | 4ft - 5ft | 1ft - 2ft | 1ft - 3ft | Moist, Occasionally Wet | https://plants.ces.ncsu.edu/plants/lobelia-cardinalis/ |
| Narrow Leaf Sunflower | Helianthus angustifolius | 5ft - 8ft | 2.5ft -4ft | 1ft - 3ft | Good Drainage, Moist, Occasionally Wet |
https://plants.ces.ncsu.edu/plants/helianthus-angustifolius/ |
| Blue Mistflower | Conoclinium coelestinum | 1.5ft - 3 ft | 1.5ft - 3ft | 1ft - 2ft | Moist, Occasional Flooding | https://plants.ces.ncsu.edu/plants/conoclinium-coelestinum/ |
| New England Aster | Symphyotrichum novae-angliae | 3 ft - 7ft | 2ft - 3ft | 1ft - 3ft | Good Drainage, Moist, Occasionally Dry |
https://plants.ces.ncsu.edu/plants/symphyotrichum-novae-angliae/ |
| Pale Meadow Beauty | Rhexia mariana | Up to 2ft tall | ??? | ??? | Moist, Occasionally Wet | https://plants.ces.ncsu.edu/plants/rhexia-mariana/ |
| Fox Sedge | Carex vulpinoidea | 1ft - 3ft | 1ft - 3ft | 1ft - 3ft | Wet | https://www.wildflower.org/plants/result.php?id_plant=cavu2 |
| Gray's Sedge | Carex grayi | 2ft - 3ft | 1.5ft - 2ft | 1ft - 2ft | Moist, Occasionally Wet | https://plants.ces.ncsu.edu/plants/carex-grayi/ |
| Swamp Rosemallow | Hibiscus grandiflorus | 6ft - 15ft | 2ft - 4ft | 3ft - 6ft | Frequent Standing Water, Occasional Flooding, Occasionally Wet |
https://plants.ces.ncsu.edu/plants/hibiscus-grandiflorus/ |
| Scarlet Rosemallow | Hibiscus coccineus | 6ft - 8ft | 2ft - 3ft | 3ft - 6ft | Moist, Occasionally Wet | 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 the start of a new pollinator garden bordering the Lamar Alexander Parkway. Native Carolina Silver bells trees (Halesia carolina) were planted near the picnic area. The TRWA rain garden is complete and 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.
