A rain garden is a shallow, planted depression designed to capture and infiltrate stormwater runoff from areas such as roofs, driveways, and lawns. Rain gardens are an important tool for reducing flooding and pollution in local waterways caused by stormwater runoff. They also help recharge groundwater supplies and provide beautiful landscaping features.

Choosing the right plants is critical for a successful rain garden. The ideal plants are native perennials that can withstand both wet and dry conditions. They have deep root systems to promote infiltration and help uptake pollutants from stormwater. Aesthetically pleasing flowers, foliage and texture also provide landscape interest. Here are 12 excellent plant choices for rain gardens in many regions of North America.

1. Cardinal Flower

The brilliant red flowers of cardinal flower (Lobelia cardinalis) make it one of the most striking herbaceous plants for a rain garden. It thrives in moist soils and tolerates flooded conditions well. Cardinal flower grows 2-4 feet tall on erect, square stems lined with lance-shaped leaves. The flowers attract hummingbirds with their nectar. Cardinal flower is hardy in zones 2-9. It spreads moderately through rhizomes and self-seeding to form dense clumps over time.

2. Great Blue Lobelia

Similar to its cardinal flower relative, great blue lobelia (Lobelia siphilitica) boasts beautiful floral displays and an ability to handle wet soils. The flowers are light blue with white interiors, blooming in late summer on stems rising 1-3 feet above clumps of green foliage. Great blue lobelia thrives in full sun to part shade and moist to saturated soil. It spreads slowly via rhizomes to form colonies. This lobelia is hardy in zones 3-9.

3.Swamp Milkweed

Swamp milkweed (Asclepias incarnata) brings height and vivid color to rain gardens, growing 3-5 feet tall on stout, upright stems. Clusters of bright pink flowers bloom from mid to late summer, followed by attractive seed pods in fall. The flowers attract butterflies and hummingbirds. Swamp milkweed flourishes in consistently moist soils and areas that are flooded for short periods. It spreads moderately through underground rhizome root systems. This attractive and versatile milkweed is hardy in zones 3-9.

4. Blue Flag Iris

The showy flowers of blue flag iris (Iris versicolor) shine in rain gardens from late spring to early summer. The sword-like green leaves provide a nice texture contrast. This tough iris tolerates both wet and dry conditions once established, plus it can handle areas with standing water. Blue flag iris grows 2-3 feet tall and spreads readily by rhizomes to form clumps. It is hardy in zones 3-9.

5. New England Aster

New England aster (Symphyotrichum novae-angliae) blooms prolifically with purple flowers and yellow centers from late summer into fall. It thrives in rain gardens and attracts butterflies. This aster grows 3-6 feet tall on leafy, erect stems. The narrow leaves are lance-shaped and arranged alternately along the stems. New England aster spreads moderately through rhizomes and self-seeding. It is cold hardy in zones 3-8.

6. Blue Vervain

A favorite of pollinators, blue vervain (Verbena hastata) blooms from summer into fall with spikes of small purple-blue flowers. The stiff, upright clumps of this plant grow 3-5 feet tall. Blue vervain flourishes in moist soils, including areas that experience periodic flooding. Once established, it is quite drought tolerant as well. This herbaceous perennial spreads moderately through seeds and rhizomes. It is cold hardy in zones 4-9.

7. Culver’s Root

Featuring tall spires of white flowers from mid to late summer, Culver’s root (Veronicastrum virginicum) is an excellent rain garden plant. It grows 3-6 feet tall on upright, leafy stems. The narrow, pointed leaves are whorled around the stem. Culver’s root spreads slowly through rhizome root systems to form upright clumps. It prefers consistently moist soils and will tolerate short periods of standing water. Culver’s root is hardy in zones 3-9.

8. Black-Eyed Susan

A rain garden classic, black-eyed Susan (Rudbeckia fulgida) provides cheery color from summer into fall with bright yellow, daisy-like flowers and prominent dark brown centers. This popular perennial grows 2-3 feet tall on branching upright stems clad with hairy, light green leaves. Black-eyed Susan thrives in moist soils and spreads vigorously through self-seeding and rhizomes. It is cold hardy in zones 4-9.

9. Switch Grass

With its upright form and graceful, airy flowers, switch grass (Panicum virgatum) adds excellent vertical interest to rain gardens. This adaptable, warm-season grass grows 3-5 feet tall and spreads slowly through rhizomes. The delicate flower spikes emerge pinkish in summer, then turn beige. Switch grass thrives in wet soils but also tolerates drought once established. For rain gardens, opt for the native species over cultivars. It is hardy in zones 5-9.

10. Blue-Eyed Grass

Despite its name, blue-eyed grass (Sisyrinchium angustifolium) is actually an herbaceous perennial plant, not a true grass. This lovely rain garden plant grows 8-12 inches tall on slender stems lined with sword-shaped, green leaves. The unique flowers have six petals of an intense violet-blue color surrounding tiny yellow centers. Blooming in spring and early summer, blue-eyed grass spreads readily by rhizomes and self-seeding. It is hardy in zones 4-9.

11. Golden Alexander

Also known as zizia, golden Alexander (Zizia aurea) brightens up rain gardens with its cheery yellow flower clusters blooming in late spring. The flowers sit atop 2-3 foot tall plants with green, carrot-like foliage. Golden Alexander readily self-seeds and fills in an area over time. It prefers consistent moisture but can handle some drier conditions once established. This perennial is hardy in zones 3-9.

12. Wild Bergamot

With fragrant leaves and showy blooms, wild bergamot (Monarda fistulosa) is an excellent rain garden plant for pollinators. The lavender-pink flowers bloom from late spring through summer on 2-4 foot tall plants. Wild bergamot spreads vigorously through rhizomes and self-seeding to form large clumps. It prefers moist soil but can tolerate some drought once established. This member of the mint family is hardy in zones 4-9.

Designing Your Rain Garden

Properly designing and constructing a rain garden provides the conditions plants need to thrive. Here are some key tips:

Choose a location downslope from runoff sources that allows for ponding and infiltration. Avoid steep slopes and low-lying wet spots.
Amend soil if needed to improve drainage. A blend of about 60% sand, 20% topsoil and 20% compost or leaf litter works well.
Make the garden shallow, with depressions 6-12 inches deep to allow ponding. Build gently sloped sides.
Pick native plants suited to intermittent flooding and your local climate. Mix species with various bloom times.
Space plants appropriately and water them while establishing roots the first year.
Add compost mulch around plants to suppress weeds and retain moisture during droughts.
Maintain the rain garden by weeding, pruning and replacing dead plants as needed.

Choosing Your Plants

Here are some tips for selecting the best rain garden plants:

Favor native perennials over annuals or non-native species. Natives are adapted to local soils and climate.
Seek a mix of grasses, sedges, rushes and flowering plants for diversity.
Choose plants suitable for the light and moisture levels in your garden site.
Pick plants with staggered bloom times for visual interest through the seasons.
Include some that spread readily to help fill in the garden over time.
Avoid invasive species that might spread aggressively into unwanted areas.
Select plants with deep root systems to aid stormwater infiltration.
Consider height and form to provide layered structure and habitat.

Caring for Your Rain Garden

Maintenance is important in the first years after installation to help plants establish deep roots. Follow these rain garden care tips:

Water plants regularly (unless rains suffice) for the first two years.
Weed frequently early on to prevent invaders from taking over.
Prune and thin plants as needed to improve air circulation.
Add additional mulch as existing layers decompose.
Replace dead plants, giving consideration to plant spacing and design.
Eco-friendly pest remedies may be needed on vulnerable species.
Remove sediment and debris that accumulates in the garden depression.
Check for erosion issues and fix them promptly to avoid drainage problems.

Benefits of Rain Gardens

Installing a properly designed and maintained rain garden on your property provides many beneficial effects:

Reduces flooding and erosion: Rain gardens collect and absorb runoff that could otherwise cause erosion and watershed flooding issues during storms. The ponded water infiltrates soil instead of flowing unchecked into local water bodies.
Improves water quality: Rain gardens act as biofilters that remove contaminants and sediment from stormwater through absorption by soil and plants. This helps protect and improve the health of nearby streams, lakes and groundwater.
Recharges groundwater: The excellent drainage in rain gardens allows stormwater to percolate down through soil and recharge local groundwater supplies rather than simply running off the surface.
Enhances wildlife habitat: The diverse native plants in rain gardens attract a wide range of pollinators, birds and beneficial insects by providing food sources and sheltered places to nest and breed.
Beautifies landscapes: With their vibrant floral displays and fascinating plant textures, rain gardens are a gorgeous alternative to conventional lawns and landscaping.

Common Questions About Rain Gardens

Here are answers to some frequently asked questions about rain garden benefits and care:

Does a rain garden form a pond?

The ponded water in a rain garden should drain within 24 hours after a storm. Faster drainage is even better to prevent mosquito breeding. The garden will not contain a permanent pond, though some pooled water may remain in very heavy rains.

What size rain garden do I need?

Size your rain garden to be about 20-30% of the total drainage area that will feed runoff to the site. For example, a 100 square foot roof would need about a 20-30 square foot rain garden. Larger is OK if space allows.

How much sun does a rain garden need?

Most rain garden plants need at least 4-6 hours of direct sun daily. Avoid heavily shaded sites under trees or the sides of buildings. Morning sun with some afternoon shade is ideal in warmer climates.

Should I fertilize a rain garden?

Do not use fertilizer in an established rain garden, as it can contaminate runoff. The native plants are adapted to thrive without amendments. Only add compost during garden construction to enrich the initial plantings if needed.

Can I walk on a rain garden?

Avoid excessive foot traffic through a rain garden, as it can compact the loose soil. Install stepping stones or a mulch path on one side if you need routine access through the garden. The plants will appreciate minimal disturbances.

Conclusion

Creating a well-designed rain garden with appropriate native plants is a rewarding way to manage and treat stormwater responsibly while enhancing your landscape. The 12 plants profiled here are excellent choices that can withstand both temporary ponded water and drier periods. A properly maintained rain garden will provide ecological benefits and visual appeal for many years. Consider installing one or more of these shallow, vegetated depressions around your home today to put storm runoff to good use in both rural and urban environments.

12 Plants That Are Perfect for Your Rain Garden