Trees and shrubs that soak up water: what they can do for a wet yard, and the natives for a rain garden

Trees and shrubs soak up water to replace what their leaves give off, so they take up the most in summer and little in spring, before leaf-out. They help ground that drains within a day or two after rain, but they cannot dry a spot where water stands for weeks. Where the water stays, plant natives built for wet feet, such as bald cypress, swamp white oak and buttonbush. Where runoff from a roof is the trouble, a rain garden of native shrubs catches it and lets it soak in.

Will a tree dry out a wet yard?

A tree will not dry a wet yard on its own. At least 90 percent of the water a plant loses goes out through its leaves, by transpiration. Soil stays moist longest in the cool days of spring and fall and dries much faster in summer, as heat and transpiration rise. A tree still bare in early spring does little for a soggy lawn.

A review of 52 studies of whole-tree water use found that nearly nine in ten measurements of peak daily use fell between about 3 and 53 gallons, for trees averaging 69 feet tall. An inch of rain on 1,000 square feet of roof yields about 600 gallons, more than ten times the top of that range.

Plants still help where water drains away within a day or two, since roots take up excess water. Where it stands for weeks, the cause lies in the site: a low spot, a downspout’s flow, packed clay or a claypan. The bucket test in native trees and shrubs for heavy clay shows how fast your ground drains.

Natives that take wet feet

Where the water stays, plant for it instead of fighting the ground:

“It is much more cost-effective to plant the right species for the location than to try to adjust the site conditions.” (University of Illinois Extension, Some trees weather wet soils, floods better than others)

We grow all nine trees and shrubs below, and each takes saturated or flooded ground. They run tallest first.

Bald cypress, smooth alder and buttonbush grow in standing water, while the other trees above want floods that drain away. Trees at home in wet soil often root shallow, so expect their roots at or near the surface as they grow. The tree finder lists every plant we grow for wet ground, narrowed to your zone, size and sun.

A rain garden, and the shrubs for each part

A rain garden is a shallow planted basin, about 6 inches deep, that catches runoff from a roof or pavement. The water soaks into the soil, goes to the plants or evaporates. It stands for hours after a storm, and a well-made garden drains within 24 to 48 hours. Its plants must take both wet and dry spells. The garden belongs where water soaks in, never in the corner that stays wet:

“Avoid placing the rain garden in a low spot in the yard that always seems wet. A rain garden is not a water garden or a wetland.” (University of Connecticut, Siting and Sizing)

The University of Tennessee’s rain garden list marks each plant for one or more of three places in the bowl. The bottom stays wet longest:

• Winterberry: a deciduous holly for ground that floods, with red berries on bare branches through winter. Male and female plants are separate, so plant a group. Zones 3 to 9, 6 to 12 feet.
• Virginia sweetspire: it stands in water after a storm without harm, and its root suckers spread it into a colony. Zones 5 to 9, 3 to 6 feet.

The side slope stays moderately wet:

• Sweet pepperbush: fragrant white spikes from July into August, on a shrub that takes standing water but wilts in dry soil until its roots are down. Zones 4 to 9, 4 to 8 feet.
• Inkberry: an evergreen holly that takes wet ground and occasional floods but not dry soil. Zones 4 to 10, 5 to 10 feet.

The rim, near the lip, is the driest:

• Black chokeberry: it grows on any moisture from a dry ridge to a wet ditch, and birds take its purplish black fruit in winter. Zones 3 to 8, 3 to 6 feet.
• Arrowwood viburnum: it takes flooding and, once established, drought, and migrating birds take its blue-black fruit first. Zones 2 to 8, 5 to 10 feet.

Where to start

Match the plant to how long the water stays, then use our tools:

• Tree finder: the trees and shrubs we grow for wet ground, by zone, size and sun.
• Wet Spot Pack: six natives chosen together for ground that floods in spring, such as a swale, a pond edge or a ditch bank.
• Planting-site check: a verdict on swamp white oak in wet ground. Add your zone and sun, or change the species.

Blue Whale Trees grows every plant in the table and the lists from seed. Our shop lists the shrubs for wet ground together.

Common questions

What trees absorb the most water?

Trees in full summer leaf draw the most water, yet in a review of 52 studies, trees averaging 69 feet tall mostly peaked at 3 to 53 gallons a day. For a wet yard, plant trees that take wet ground, such as bald cypress, pin oak and swamp white oak.

What shrubs grow in standing water?

Buttonbush grows in standing water up to 3 feet deep, and smooth alder thrives in it. Virginia sweetspire stands in water after a storm without harm, and winterberry takes ground that floods.

How far from a house should a rain garden be?

At least 10 feet from a house with a basement, since water soaking in near the foundation can cause water problems in the basement. Keep it off a septic system and away from a drinking-water well too.

Will a rain garden breed mosquitoes?

Not if it drains as it should. A well-made rain garden holds water for only about 6 hours after a storm, and mosquitoes need much more time than that to lay eggs that hatch.

Sources

• A review of whole-plant water use studies in trees: S.D. Wullschleger, F.C. Meinzer and R.A. Vertessy, Tree Physiology 18 (1998): 52 studies of whole-tree water use since 1970, and peak daily use of 10 to 200 kilograms for nearly nine in ten measurements, on trees averaging 21 meters tall.
• Watering established trees and shrubs: University of Minnesota Extension: at least 90 percent of a plant’s water lost through its leaves by transpiration, and soil that stays moist longer in the cool days of spring and fall and dries faster in summer.
• Rain Barrels: University of Wisconsin-Madison Extension: about 600 gallons from an inch of rain on 1,000 square feet of roof.
• Some trees weather wet soils, floods better than others: University of Illinois Extension: roots taking up excess water, downspout discharge in choosing a site, shallow roots on trees of wet soil, and the cost of planting for the site rather than changing it.
• Baldcypress: USDA Forest Service, Silvics of North America, with the chapters on pin oak, river birch, swamp white oak and sweetbay: frequent, prolonged flooding on bald cypress sites, pin oak’s dormant-season floods, river birch’s limit of 3 months under water in the growing season, swamp white oak’s absence where flooding is permanent, and sweetbay’s seasonal shallow floods.
• Nyssa sylvatica, N. biflora, Fire Effects Information System: USDA Forest Service: black gum tolerating brief spring flooding.
• Cephalanthus occidentalis: NC State Extension Gardener Plant Toolbox, with its page for Itea virginica: buttonbush in standing water up to 3 feet, and Virginia sweetspire’s tolerance of periodic flooding and its use in rain gardens.
• Siting and Sizing: University of Connecticut, Center for Land Use Education and Research, with its Frequently Asked Questions page: a rain garden kept out of the low spot that always seems wet, a garden 6 inches deep, 10 feet from a house with a basement, clear of septic systems and wells, and about 6 hours of standing water against the far longer time mosquitoes need.
• Rain Gardens: University of Maryland Extension: a planted basin whose water is absorbed into the soil, taken up by plants or evaporated, native plants that take wet and dry conditions, and drainage within 24 to 48 hours.
• Tennessee Native Rain Garden Plant Recommendations: University of Tennessee Extension (2019): the lower, middle and upper places in a rain garden, from persistently wet to driest, and the places marked for winterberry, Virginia sweetspire, summersweet, inkberry, black chokeberry and arrowwood.