Using Rain Gardens To Keep Waterways Pollution Free

Keep reading to see how a neighborhood building project beautified the streetscape of a neighborhood, while keeping pollutants out of local waterways. We’ll even share their plant suggestions, plans, and pointers—so get your notepad out.

It Takes a Village

On a sunny day last September, dozens of neighbors in the western Washington town of Puyallup were out in their front yards, elbow-deep in dirt. They were planting a half-dozen saucer-shaped beds, the finale to a weeklong building blitz to turn two 18th Street blocks into a rain-garden demonstration project. By ushering storm runoff into the soil, rather than letting it flow down oily streets, the new planting beds would protect one of the community’s greatest assets, Clarks Creek, where five species of salmon lay their eggs.

Wildlife-Friendly Rain Gardens

The gardens would also make the neighborhood more beautiful and attract birds and butterflies. As a bonus, the city was picking up the tab for the work, since it would serve as a teaching tool to encourage similar installations in the area. The neighbors just had to help plant, and promise to care for, the new gardens. “It was a fabulous opportunity, too good to pass up,” said neighborhood organizer Heidi Eshpeter (left, pictured with fellow community-gardener Paula Hemphill). “When you live near a salmon stream, everybody needs to do their part.”

How a Rain Garden Works

While they may seem just like pretty little front-yard flower beds, rain gardens function like mini forests by soaking up and filtering rainwater runoff, usually from a downspout, before it runs down oily streets and reaches natural waterways. Because details about size, soil mixture, and plants depend on local conditions, university extension programs are developing tailored advice for many regions. But here are the key components. Inlet: Roof runoff is channeled into a buried pipe that carries water into the rain garden. Ponding Depth: The saucer-shaped basin is designed to hold 6 to 12 inches of rainwater during a storm. Overflow: A gravel-filled trench collects and disburses water, should the garden overfill. Mulch: A 3- to 4-inch-thick layer of mulch helps trap moisture. Soft Soil Mix: A blend of compost and native soil (or sand) absorbs and filters runoff.

Organizing Your Garden

Think of a rain garden as areas of varying degrees of moisture within the same bed. Since the outer edges of a rain garden dry out faster than the center, plants that work well in the middle might not do as well along the perimeter. In the center (Zone 1), where it’s wettest, you need plants that thrive even in mucky soil. Around that, put plants that can tolerate occasional standing water (Zone 2). Plants for the edges and berm should prefer drier conditions, as they seldom stay under water very long (Zone 3). Ideally, rain-garden plants should also survive dry seasons without irrigation, so the best plants are probably the native ones that grow near seasonal wetlands in your area. Using locally native plants also eliminates worries about introducing invasive plants, a particular issue with rain gardens because the growing conditions are ideal for many species.

Ornamental Grasses and Shrubs

Of course, rain gardens aren’t just for those with well-known fish-spawning grounds nearby. They are helping turn storm-water problems into landscaping amenities all across the country—filtering out pollutants and keeping them from washing into waterways, and allowing rain to percolate back into the soil, where it can replenish the water table. In dry desert areas and in city gardens with shallow soil, they make the most of every rainfall." See the plant list for a green rain garden like this one next.

A Place to Play and Nibble

The homeowner wanted a garden where her young daughter could have fun poking around and finding a few berries to eat, so there are edible berries, billowing grasses, and no poisonous plants.

1. Mugo Pine
2. ‘Ice Dance’ Japanese Sedge
3. Coastal or Beach Strawberry
4. Blue Fescue
5. Tufted Hair Grass
6. Blue Oat Grass Not Pictured:
7. Evergreen Huckleberry
8. Salal
9. Dagger-leaf or Sword-leaf Rush
10. ‘Fireglow’ Japanese Maple
11. Kelsey Dwarf Dogwood
12. ‘Ice Dance’ Japanese Sedge
13. Variegated Lily Turf
14. Black-eyed Susan

Pretty Plant Mix

Homeowners don’t usually have the luxury of getting free rain gardens, of course. But teaming up with neighbors to put in a half-dozen or more at once is still a great idea. It multiplies the environmental benefits, reduces the work, and saves money. Neighbors can pool orders for plants and compost and share the cost of bringing in a crew with an earth-moving machine. Rain gardens vary in their final look, though not their basic key components, which we explored in How a Rain Garden Works. For the plant list for the garden shown here, click next.

A Mixed Perennial Garden

With familiar garden favorites that flower yellow, blue, and purplish-pink and provide season-long interest, you might not know this was a rain garden but for its basin shape, off-street siting, and patch-of-gravel overflow outlet.

1. ‘Moonshine’ Yarrow
2. ‘Hidcote’ English Lavender
3. Purple Coneflower
4. ‘Blue Star’ Juniper
5. ‘Stella de Oro’ Daylily
6. Tufted Hair Grass Not Pictured:
7. Nepeta
8. Pacific Ninebark
9. Red-twig Dogwood
10. ‘Ice Dance’ Japanese Sedge
11. Yellow-Eyed Grass
12. Low Oregon Grape
13. ‘Silver Knight’ Heather
14. ‘Kobold’ Blazing Star

A Mix of Perennials

It is the combination of hardy plants and soft soil that allows rain gardens to work their magic, says David Hymel, who coordinated the Puyallup project for Stewardship Partners, a Seattle nonprofit that is trying to build 12,000 rain gardens in the Puget Sound area. “The whole idea is to have the water be absorbed back into the ground and filtered naturally, the way it used to be when the area was still forest,” he says. For the vibrant plants featured in this garden, click next.

A Garden for Symmetry and Color

Anchored by a pair of matching shrubs at both ends and limited mostly to various shades of green and purple, this rain garden looks especially well planned. The colors contrast pleasantly with the blue house.

1. Salal
2. Pacific Ninebark
3. ‘Ice Dance’ Japanese Sedge
4. ‘Autumn Joy’ Sedum Not Pictured:
5. ‘Summer Wine’ Ninebark
6. Slough Sedge
7. Idaho Fescue
8. Red-Hot Poker
9. ‘Bumalda’ Spiraea
10. ‘Hidcote’ English Lavender
11. Dwarf Mugo Pine
12. ‘Moonshine’ Yarrow
13. Tufted Hair Grass
14. Blue Fescue
15. Evergreen Huckleberry
16. Kinnikinnick or Bearberry

Easy-Care Grasses

Before the 18th Street rain gardens in the western Washington town of Puyallup, roof runoff flowed into the street, picking up oil and other pollutants from the pavement before disappearing into a storm drain that flushed directly into the salmon stream. In a storm, it took just minutes for the creek to rise rapidly, causing erosion that covered gravel spawning beds with silt. Now, gutter water is channeled into the rain gardens, where plant roots and the spongy soil absorb the water over the next day or two, and the water trickles into the surrounding earth. It still moves toward the creek, but underground, so it stays clean and cold, keeping the fish happy. To see the plant list for the garden shown here, click next.

Grasses That Move and Sway

A variety of billowing, grasslike plants give this garden its calming look. In a breeze, the undulating blades almost look like gentle waves in the ocean. Grasses That Move and Sway A variety of billowing, grasslike plants give this garden its calming look. In a breeze, the undulating blades almost look like gentle waves in the ocean.

1. Mexican Feather Grass
2. Leather-leaf Sedge
3. Blue Oat Grass
4. Kelsey Dwarf Dogwood
5. ‘Ice Dance’ Japanese Sedge
6. ‘Little Bunny’ Dwarf Fountain Grass Not Pictured:
7. Japanese Blood Grass
8. Heavenly Bamboo
9. Tufted Hair Grass

Curb Appeal With Colorful Flowers

How were the Puyallup rain gardens received? “Mine does everything I wanted,” community-gardener Heidi Eshpeter says. “Before, I had standing water in front of my doorway when it rained. Now the downspout water is piped directly into the rain garden.” Her entry remained dry all last winter, one of the wettest on record. Strolling along streets is a popular pastime in Puyallup, and passersby often pause to read signs explaining the rain gardens. Says Heidi, “People will ask, ‘Can we come up and look?’ I say, ‘Sure.’ That’s the whole purpose. It’s great that we can spread the word.” Click next to see the plant list for the flower-filled garden shown here.

For Flower Lovers

This rain garden suits a dedicated gardener who loves flowers and is willing to clip back fading blooms so that the plants stay tidy.

1. Red-twig Dogwood
2. Mugo Pine
3. Black-eyed Susan
4. Russian Sage
5. Purple Coneflower
6. ‘Autumn Joy’ Sedum Not Pictured:
7. Low Oregon Grape
8. ‘Kobold’ Blazing Star
9. Kinnikinnick or Bearberry
10. Kelsey Dwarf Dogwood
11. Variegated Lily Turf

More Ornamental Grasses

Just as with a standard garden bed, a rain garden can emphasize a particular color. Here it’s the orange-brown of the house siding, accented by the white of the trim.

1. Red-twig Dogwood
2. Mugo Pine
3. Coastal or Beach Strawberry
4. Leather-leaf Sedge Not Pictured:
5. ‘Silver Knight’ Heather
6. ‘Blue Star’ Juniper
7. Compact Oregon Grape
8. ‘Ice Dance’ Japanese Sedge
9. Yellow-Eyed Grass
10. Snowberry
11. Variegated Lily Turf

More No-Fuss, Neat and Tidy Plants

This rain garden is all about looking fine with little care. There are no flowers to clip or spent perennials to cut back, yet the garden still looks interesting because of the subtle color and texture variations.

1. Mugo Pine
2. Red-twig Dogwood
3. Snowberry
4. Blue Fescue
5. ‘Ice Dance’ Japanese Sedge Not Pictured:
6. Tall Oregon Grape
7. ‘Darts Gold’ Ninebark
8. Black Mondo Grass
9. Blue Oat Grass
10. Tufted Hair Grass
11. Low Oregon Grape
12. ‘Silver Knight’ Heather

Rain Garden Plant List

Leather-leaf Sedge (Carex buchananii) Because the leaf blades match the color of the siding and color matching is the theme, the sedge is front and center. Flowers aren’t showy. Zone: 3; Hardy to 0 degrees F Height: Up to 2 feet.

Coastal or Beach Strawberry

(Fragaria chiloensis) The glossy green leaves of this wild strawberry look attractive year-round. The plant spreads rapidly by runners, so it’s a groundcover here. White flowers. Zone: 2 or 3; Hardy to at least 15 degrees F Height: up to 10 inches. Hardy to at least 15 degrees F.

Red-twig Dogwood

(Cornus sericea, syn. C. stolonifera, Swida sericea) Native to most of the U.S., this deciduous shrub has bright reddish-brown stems in winter. It was planted where it will grow to add privacy to the front window. Zone: 1 or 2; Hardy everywhere Height: 6 to 15 feet.

‘Silver Knight’ Heather

(Calluna vulgaris) Silver-gray leaves take on a purple cast in winter and are overtaken by sprays of flowers in summer. Lavender flowers. Zone: 3; Hardy everywhere Height: up to 16 inches.

‘Blue Star’ Juniper

(Juniperus squamata) Hardy conifer produces uniform branches covered with dense, silver-blue foliage. No flowers. Zone: 2; Hardy everywhere Height: up to 3 feet.

Compact Oregon Grape

(Mahonia aquifolium ‘Compacta’) Though most mature leaves on this evergreen shrub are green, new leaves and some mature ones in fall fit the bronze-red color scheme. Yellow flowers. Zone: 3; Hardy to –20 degrees F Height: up to 3 feet.

‘Ice Dance’ Japanese Sedge

(Carex morrowii) This grasslike plant forms tidy mounds of green blades edged in white. Insignificant flowers. Zone: 1. Hardy to –30 degrees F Height: up to 12 inches.

Yellow-Eyed Grass

(Sisyrinchium californicum) An iris relative, this West Coast native has grasslike leaves and petite flowers that open on sunny days in spring and early summer. Yellow flowers. Zone: 1, 2, or 3; Hardy to 10 degrees F Height: up to 12 inches.

Snowberry

(Symphoricarpos albus) This shrub, native to the western U.S., produces white fruit that stays on even after the leaves drop, attracting birds. The berries are poisonous to humans. Pink flowers. Zone:A tough plant for 2 or 3. Hardy everywhere Height: up to 6 feet.

Variegated Lily Turf

(Liriope muscari ‘Variegata’) Forming soft clumps of grasslike leaves, lily turf is a good groundcover or edging for a rain garden. The variegated form has green leaves edged in creamy yellow, though the yellow disappears as the leaves age. Violet flowers. Zone: 1 or 2; Hardy to –30 degrees F Height: up to 20 inches.

Mugo Pine

(Pinus mugo) This slow-growing conifer has unusually dense needles. It eventually spreads 15 feet, twice as wide as its mature height, so it’s planted at the back, where it will grow to shelter the house from the street. Produces 2-inch-long cones. Zone: 3. Hardy everywhere Height: up to 8 feet.

Russian Sage

(Perovskia atriplicifolia) Gray-green leaves and sprays of small flowers add textural contrast among plants with bolder flowers. It’s at the front, where visitors can enjoy its scent as they brush against the leaves. Lavender-blue flowers. Zone: 3; Hardy to –30 degrees F Height: up to 36 inches.

‘Autumn Joy’ Sedum

(S. ‘Herbstfreude’) Long-lasting flower clusters make this succulent a standout in a rain garden in late summer and fall. Grown as an accent plant in this garden. Pink to rust-colored flowers. Zone: 3; Hardy everywhere Height: 1 to 2 feet.

Black-eyed Susan

(Rudbeckia fulgida) Descended from plants native to the eastern U.S., this showy coneflower blooms in late summer and fall. A perennial that dies back to the ground in winter, it needs plenty of room to spread as the summer progresses. Golden yellow flowers with dark centers. Zone: 3; Hardy everywhere Height: up to 3 feet.

Low Oregon Grape

(Mahonia nervosa) This evergreen shrub has cascades of spiny green leaves most of the year, but in fall many turn fire red. Plant does especially well in shade. Yellow flowers. Zone: 2 or 3. Hardy to –10 degrees F Height: up to 2 feet.

‘Kobold’ Blazing Star

(Liatris spicata) This eastern U.S. native produces spikes of flower clusters in summer. Adds a nice vertical feature to a relatively dry part of the rain garden. ‘Kobold’ is about half as tall as some selections. Rosy lilac flowers. Zone: 3; Hardy to –40 degrees F Height: up to 2 feet.

Kinnikinnick or Bearberry

(Arctostaphylos uva-ursi) A manzanita relative, this evergreen with small leathery leaves and red berries grows slowly but eventually forms a dense mat that chokes out weeds. Rosy lilac flowers. Zone: 3; Hardy to –50 degrees F Height: up to 6 inches.

Kelsey Dwarf Dogwood

(Cornus sericea ‘Kelseyi’) A dwarf form of red-twig dogwood with the same bright-red bark in winter. Berries attract birds. White flowers. Zone: 1 or 2; Hardy to –50 degrees F Height: up to 30 inches.

Tufted Hair Grass

(Deschampsia cespitosa) With gracefully cascading thin leaves, airy wands of flowers, and, later, seeds, this perennial bunchgrass stays attractive most of the year. Green to greenish-gold flowers. Zone: 1 or 2; Hardy to –40 degrees F Height: up to 24 inches.

Blue Oat Grass

(Helictotrichon sempervirens) A Mediterranean import, this tidy grass produces a fountain of blue-green leaves. Two clumps dominate the front of the garden. Golden flower clusters. Zone: 3; Hardy everywhere Height: up to 36 inches.

Evergreen Huckleberry

(Vaccinium ovatum) With glossy leaves year-round, bell-shaped flowers in spring, and tasty blueberry-type fruit in fall, this shrub, a western U.S. native, is easy to love. But it grows very slowly for the first couple of years, so it’s hardly noticeable. White to pink flowers. Zone: 3; Hardy to 0 degrees F Height: up to 3 feet in sun or 12 feet in shade, but can be pruned back.

Blue Fescue

(Festuca ovina var. glauca) A finely textured, clump-forming grass with wands of buff-colored seeds in late summer and fall. Planted at the far end of the garden. Flowers aren’t showy. Zone: 2; Hardy to –30 degrees F Height: up to 12 inches.

Salal

(Gaultheria shallon) Popular among florists as a foliage plant, salal is a northwest U.S. native that thrives in sun or shade, and it produces delicious but fuzzy berries as a bonus. White to pink flowers. Zone: 3; Hardy to –40 degrees F Height: up to 5 feet.

Dagger-leaf or Sword-leaf Rush

(Juncus ensifolius) Native to most of the western U.S., this perennial forms dense, grasslike clumps. Insignificant flowers. Zone: 1; Hardy to –20 degrees F Height: up to about 2 feet.

‘Fireglow’ Japanese Maple

(Acer palmatum) This small tree sends out leaves that are almost purple in spring; they later change to a brilliant crimson. Because the branches will spread, it’s planted toward the center. Insignificant flowers. Zone: 2; Hardy to –20 degrees F Height: up to 15 feet.

Tall Oregon Grape

(Mahonia aquifolium) Intriguing glossy but spiky leaves turn red in fall and winter. Showy flowers in spring develop into tart, edible berries that look like purple grapes. Grows tall, so it’s at the back. Yellow flowers. Zone: 2; Hardy to –30 degrees F Height: up to 15 feet.

‘Darts Gold’ Ninebark

(Physocarpus opulifolius) The leaves start out yellow, turn chartreuse by mid-summer, then become yellow or bronze in fall—at every stage, a nice contrast to other plants. The branches are bare in winter, then you notice the peeling bark typical of all ninebarks. White flowers. Zone: 1 or 2; Hardy to –40 degrees F Height: up to 5 feet.

Black Mondo Grass

(Ophiopogon planiscapus ‘Nigrescens’) This lily is grown for its especially dark, purplish-black leaves. In this garden, the plant is interspersed with blue oat grass to make its leaves seem even bluer. The mondo grass also intensifies the chartreuse of ‘Dart’s Gold’ ninebark. White or purplish flowers. Zone: 2 or 3; Hardy to 0 degrees F Height: up to 12 inches.

Pacific Ninebark

(Physocarpus capitatus) Named for the way it sheds its outer bark in strips to reveal multicolored inner layers, this native shrub of the northwest U.S. also has flowers that look like single roses in spring and interesting red seed pods in fall. White flowers. Zone: 1 or 2; Hardy to –20 degrees F Height: up to 8 feet.

‘Summer Wine’ Ninebark

(Physocarpus opulifolius) This purple-leaved ninebark is used at each end of this rain garden. It has the same beautiful peeling bark and interesting seed capsules as the standard ninebark. Pinkish-white flowers. Zone: 1 or 2; Hardy to –40 degrees F Height: up to 6 feet. .

Slough Sedge

(Carex obnupta) This clump-forming perennial, with grasslike leaves creased down the middle, stays green and lush-looking even when dry. It’s taller than some similar plants, so it’s at the center. Insignificant flowers. Zone: 1;Hardy to 0 degrees F Height: up to 5 feet.

Idaho Fescue

(Festuca idahoensis) A relatively petite bunchgrass, native to the western U.S., this fescue has thin, bluish-green leaves. It can be planted in a mass to create a meadow look, but in this garden it fills gaps. Insignificant flowers. Zone: 2; Hardy everywhere Height: up to 14 inches.

Red-Hot Poker

(Kniphofia uvaria) From southern Africa, this lily relative produces large clumps of grasslike leaves topped by flower spikes that resemble glowing pokers for a fire. Hummingbirds love them. Red and yellow flowers. Zone: 3; Hardy to –30 degrees F Height: up to 5 feet.

‘Bumalda’ Spiraea

(Spiraea japonica) New leaves are tinted bronze on this shrub, which has flat clusters of dark-pink flowers in summer. Zone: 2; Hardy to –40 degrees F Height: up to 3 feet.

‘Hidcote’ English Lavender

(Lavandula angustifolia) Suitable for flavoring food as well as scenting perfume and sachets, ‘Hidcote’ is easy to grow where the air is dry but more difficult in humid areas. A rain-garden berm makes a good home. Deep-purple flowers. Zone: 3; Hardy to –20 degrees F Height: up to 18 inches.

Dwarf Mugo Pine

(Pinus mugo var. pumillow) It has the same dense, dark-green needles of standard mugo pine, but grows slowly to only 5 feet. No flowers. Zone: 3; Hardy to –50 degrees F

‘Moonshine’ Yarrow

(Achillea) This easy-care yarrow thrives in sunshine and blooms all summer and into fall. It’s planted at the front. Zone: 3; Hardy to –40 degrees F Height: up to 2 feet.

‘Stella de Oro’ Daylily

(Hemerocallis) Probably the best-known daylily, this variety pumps out new flowers almost daily all summer, so it’s along the side of the rain garden closest to where people walk up to the front door. Yellow flowers. Zone: 3; Hardy to –40 degrees F Height: up to 2 feet.

Nepeta

This mint produces billowing spikes of blue flowers, a nice contrast to the yellow-flowering plants nearby. Most mints reseed freely, so if you don’t want new plants springing up, cut back spent blossoms promptly or plant a sterile kind, such as catmint (N. x faassenii). Blue flowers. Zone: 3; Hardy everywhere Height: up to 4 feet.

Purple Coneflower

(Echinacea purpurea) A perennial, this plant produces daisy-like flowers with dark centers from late June into fall. The steps are tall, so the three clumps of this plant are at the back. Purplish-pink flowers. Zone: 3; Hardy to –40 degrees F Height: up to 5 feet.

Mexican Feather Grass

(Nassella tenuissima) This grass attracts attention because of its airy seed heads and thread-like leaves in an unusual blond color. In this rain garden, it’s planted where its cascading form contrasts with the stiffer, more upright blades of blue oat grass. Can be invasive. Silvery-green seed heads. Hardy to –20 degrees F Height: up to 2 feet.

Japanese Blood Grass

(Imperata cylindrica ‘Rubra’) The spiky leaves of this clump-forming grass are green at the base but transition halfway up to vibrant red. This cultivar rarely flowers, so it isn’t invasive. Hardy to –30 degrees F Height: up to 18 inches.

Heavenly Bamboo

(Nandina domestica) Unrelated to standard bamboo but with a leaf pattern that looks somewhat similar, this evergreen shrub turns red in fall. White flowers. Hardy to –10 degrees F Height: up to 8 feet.

‘Little Bunny’ Dwarf Fountain Grass

(Pennisetum alopecuroides) Finely textured grass is topped with fluffy flower heads that wave in the breeze, as if bunnies were hopping. Whitish flower plumes. Zone: 3; Hardy to –20 degrees F Height: up to 18 inches.