Guides

How to Build a Rain Garden in Maryland

A rain garden is a shallow, planted basin that catches the water rushing off your roof or driveway, lets it soak into the ground instead of flooding your yard, and filters out pollutants before they reach the Chesapeake. It turns your soggiest problem spot into the lushest, most alive part of the garden — here's one I built at my own house.

Maryland bonus: Montgomery County and Prince George's County both have generous rebate programs for installing rain gardens. Many other counties and towns have similar programs. Reach out if you have any questions and we can try to get you a garden for a big discount!

The basicsA simplified version of how I lay one out.

Test the drainage first: do a quick percolation ("perc") test so you know water will actually soak away — there are good how-to videos on YouTube. If it drains slowly, plan to loosen and amend the soil (below).
Placement: at least 10 feet from your foundation, in a low spot or where a downspout drains. Never over a septic field.
Size: roughly 20–30% of the roof/paved area draining into it; bigger is more forgiving.
Shape: dig a shallow bowl about 12–18" at its deepest, tapered on all sides and with a flat bottom; use the excavated soil to build a low berm on the downhill side.
Soil: if it drains slowly, loosen and amend with compost so water soaks away within a day (it should never hold water long enough to breed mosquitoes).
Plant in zones — wettest in the center, driest at the edges (below).

Zone 1 — the bottom (wettest)Plants that don't mind "wet feet" after a storm.

Lobelia cardinalis — Cardinal Flower. Brilliant red spikes; hummingbirds adore it.
Chelone glabra — White Turtlehead. Host plant for the Baltimore checkerspot — our state butterfly.
Iris versicolor — Blue Flag Iris. Elegant blue spring blooms in standing-wet soil.
Juncus effusus — Soft Rush. Vertical green texture that anchors the basin.

Zone 2 — the slopes (occasionally wet)

Asclepias incarnata — Swamp Milkweed. A monarch host that loves moisture; fragrant pink flowers.
Vernonia noveboracensis — New York Ironweed. Tall, deep-purple late-summer color.
Eutrochium fistulosum — Joe Pye Weed. Butterfly magnet for the back of the basin.
Panicum virgatum — Switchgrass. Roots deep, handles wet and dry, holds the soil.

Zone 3 — the edges (driest)

Symphyotrichum novae-angliae — New England Aster. Late-season purple; critical fall pollinator food.
Rudbeckia fulgida — Black-eyed Susan. Reliable gold all summer.
Itea virginica — Sweetspire. A shrub that thrives in rain-garden conditions; crimson fall.

Got a spot that floods every time it rains?

A rain garden is one of the most rewarding fixes there is — beautiful, functional, and good for the Bay. I'll design one sized for your runoff.

Get in touch to learn more