Amazing Rain Garden
Full sun to partial shade
Average to moist soil
When soil is covered up by buildings, paving, and other hard surfaces, it can’t absorb rainfall as it normally would. That water has to go somewhere, though, and often, that means it flows into sewer systems that are already overtaxed by heavy rainfall. Installing a rain barrel to collect water from your roof is one great way to reduce stormwater runoff and save on your watering bills too. Planting a “rain garden” is another great way to do your part for the environment, and you’ll end up with a gorgeous perennial planting to enjoy as well.
The Garden Plan
Shopping List
1 Culver’s root
Veronicastrum virginicum
5 plants
Zones 3–8
Alternates: Another 4- to 6-foot-tall perennial that can tolerate occasional flooding, such as swamp milkweed (Asclepias incarnata) [3 plants] or New York ironweed (Vernonia noveboracensis) [3 plants]
Culver’s root (Veronicastrum virginicum)
2 ‘Karl Foerster’ feather reed grass
Calamagrostis × acutiflora
4 plants
Zones 4–8
Alternates: Another 3- to 5-foot-tall perennial that can tolerate occasional flooding, such as ‘Rotstrahlbusch’ switch grass (Panicum virgatum) [4 plants] or ‘Little Joe’ Joe-Pye weed (Eupatorium dubium) [4 plants]
‘Karl Foerster’ feather reed grass (Calamagrostis × acutiflora)
3 Arkansas bluestar
Amsonia hubrichtii
1 plant
Zones 4–9
Alternates: Another 2- to 4-foot-tall perennial that can tolerate occasional flooding, such as a Siberian iris (Iris sibirica) [1 plant] or a turtlehead (Chelone) [1 plant]
Arkansas bluestar (Amsonia hubrichtii)
4 Blue lobelia
Lobelia siphilitica
10 plants
Zones 3–8
Alternates: Another 2- to 3-foot-tall perennial that can tolerate occasional flooding, such as Mardi Gras Helen’s flower (Helenium ‘Helbro’) [8 plants] or orange coneflower (Rudbeckia fulgida) [8 plants]
Blue lobelia (Lobelia siphilitica)
5 ‘Happy Returns’ daylily
Hemerocallis
4 plants
Zones 3–9
Alternates: Another 1- to 2-foot-tall perennial that can tolerate occasional flooding, such as ‘Miss Manners’ obedient plant (Physostegia virginiana) [4 plants] or a dwarf bee balm (Monarda) [4 plants]
‘Happy Returns’ daylily (Hemerocallis)
Planting Plan
Season by Season
Spring: The perennials in this plan tend to jump into growth in early to mid spring. The tightly whorled, green shoots of Culver’s root may be tinged with red, making an interesting contrast to the bright green blades of the grass and the daylily, the feathery foliage of the Arkansas bluestar, and the dense rosettes of blue lobelia. By late spring, the upright stems of the Arkansas bluestar are topped with clusters of pale blue, starry blooms.
Tackle cleanup chores here as soon as possible in spring. Cut down the remaining dead stems and leaves, and divide any of the perennials that were outgrowing their space by last fall. Then, spread a fresh layer of organic mulch over the soil.
Summer: Arkansas bluestar usually finishes flowering by early summer, about the time that ‘Happy Returns’ daylily starts its early to midsummer bloom period, with trumpet-shaped yellow blossoms. ‘Karl Foerster’ feather reed grass sends up its pinkish flower plumes in early summer, too; they remain for the rest of the summer, gradually turning tan. Culver’s root joins in with spiky white blooms in mid to late summer, and the blue spikes of blue lobelia come along in late summer.
As soon as the flowers fade on the Arkansas bluestar, trim established clumps back by about half to prevent self-sowing and encourage bushier new growth. On the blue lobelia, cut off the finished flower spikes just above the leafy part of the stem. And on the daylily, clip off the bloom stalks at the base when the flowers are finished. Water the garden during extended dry spells.
Fall and Winter: Fresh flowers can keep coming in fall from the blue lobelia and the ‘Happy Returns’ daylily. Arkansas bluestar contributes cheery color, too, as the leaves turn bright shades of yellow by mid fall. The dried heads of Culver’s root and ‘Karl Foerster’ feather reed grass remain attractive through the autumn, and well into winter, too.
There’s very little maintenance to do now: wait until late fall to cut down the dead stems, or leave them in place for winter interest.
Digging Deeper
- It’s smart to plant your rain garden near a downspout from a roof gutter, but be sure to keep it at least 10 feet away from your home, because you don’t want to encourage water to collect right near the foundation. Also, avoid putting it in a site that is normally slow to dry out after a storm. The point of a rain garden is to hold excess water for a very short period, not long enough to create a breeding ground for mosquitoes. So choose a well-drained site, and dig out the area to a depth of 4 to 8 inches to create a broad, shallow catch basin. If you have the room, you could easily flip this plan along the straight site to create a larger, circular bed.
- The perennials in a rain garden need to be tough enough to tolerate occasional flooding as well as drier spells between rains. They’ll still need weekly watering during their first growing season if rain is lacking, but after that, they should be fine without supplemental irrigation.
- When you mulch your rain garden — which will help to keep weeds down and hold some moisture in the soil during dry weather — avoid using very lightweight materials, such as small wood chips or cocoa hulls. These light mulches tend to float and can easily end up out of place, or even out of the garden entirely, during heavy storms. Shredded bark mulch tends to create a more solid mat that’s less likely to shift around in wet conditions.