How to Design a Beautiful Rain Garden That Thrives in Stormy Weather

Rain gardens allow stormwater runoff to infiltrate soil and return water to the aquifer, while creating a beautiful new garden bed. This fourth article in a rain garden series addresses aesthetics—once you've made yours functional with proper location, soil, and plants, these design tips help it look its best.

Countryside Flower Shop and Nursery

Work With What You Have

Inventory your space's existing assets. A favorite tree or flowering shrub gaining beauty yearly? A beloved sunny spot or extra-lush border? Consider how a rain garden enhances these. The design shown creates a lush border enhancing the surrounding healthy lawn.

Plants shown: Joe Pye Weed (Eutrochium sp.), black-eyed Susan (Rudbeckia hirta), prairie dropseed (Sporobolus heterolepis), sedge (Carex sp.), blazingstar (Liatris sp.)

Incorporate Your Existing Layout

Plan-it Earth Design

A rain garden can integrate into an existing bed by reworking soil and adding plants, or by extending a bed to capture rainwater from an adjacent slope. This narrow side yard design accommodates an adjacent stepping stone path—creeping mazus (Mazus reptans) between stones merges beautifully with rain garden plants.

Plants shown: Golden sweet flag (Acorus gramineus 'Ogon'), common rush (Juncus effusus), 'Little Henry' sweetspire (Itea virginica 'Little Henry'), thimbleberry (Rubus parviflorus)

Design With the Overall Landscape in Mind

Plan-it Earth Design

Choose plant textures, colors, and forms that complement existing plants. Want your rain garden to stand out or blend? Subjective choice—this example blends so seamlessly it's unclear where the rain garden begins and ends.

Plants shown: 'Moon Bay' heavenly bamboo (Nandina domestica 'Moon Bay'), blue fescue (Festuca glauca), 'Magic Carpet' spirea (Spiraea japonica 'Magic Carpet'), 'Aurea' barberry (Berberis thunbergii 'Aurea')

Avoid Washout and Erosion

Falon Land Studio LLC

The inflow point where water meets the rain garden is erosion-prone—water hits repeatedly with force. Place stones that won't float away. 2–3 inch stones break up rushing water; smaller gravel works on slopes under 3%. Avoid small stones on steep slopes—they'll wash out. Goal: choose stone size that spreads water as it enters.

Alternatively, plant woody spreading groundcovers tolerating inundation: creeping barberry (Mahonia repens) or kinnikinnick (Arctostaphylos uva-ursi). Fill gaps between young plants with stones—plants eventually grow over them.

Countryside Flower Shop and Nursery

Shown: concrete walkway sloped to drain into rain garden. Small crushed stone on planting bed perimeter buffers and spreads water. Plant: Louisiana Iris (Iris brevicaulis).

Plant for Fullness Over Time

Plan-it Earth Design

Like any new garden, rain gardens take time to mature. Initial spacing should reflect mature spread, giving room to grow. Avoid overcrowding—plants too close require thinning maintenance. This rain garden in early years fills nicely as plants spread and mature.

Plants shown: Joe Pye Weed (Eutrochium sp.), black-eyed Susan (Rudbeckia hirta), prairie dropseed (Sporobolus heterolepis), sedge (Carex sp.), blazingstar (Liatris sp.)

Use Woody Plants for Winter Interest

Falon Land Studio LLC

Rain gardens needn't be all grasses and herbaceous plants. Woody plants—shrubs and trees—add winter interest, even if deciduous. This Portland, Oregon rain garden intermingles woody plants with grasses and perennials for year-round appeal.

Learn From Established Rain Gardens Nearby

Photo by the Wisconsin Department of Natural Resources

A key design and maintenance strategy: study nearby established rain gardens. They're growing in popularity but remain a landscape specialty. Visit one, note plant performance, standout species, year-round appearance, and how stone/mulch holds up over time.

Shown: shaded slope draining into Houston Zoo parking lot rain garden. Wet zone plants expertly layered—fine Louisiana iris (Iris brevicaulis) foliage at edges, taller water-loving powdery thalia (Thalia dealbata) in center.