The gardening term “wet feet” describes a condition where a plant’s roots are consistently sitting in waterlogged or saturated soil. For the vast majority of plants, this environment is detrimental because water fills the soil pores, displacing oxygen. The lack of oxygen quickly creates anaerobic conditions, which suffocates the roots and prevents them from performing aerobic respiration. This oxygen deprivation ultimately leads to root decay. Certain specialized plants, known as hydrophytes, have evolved remarkable mechanisms that allow them to thrive in these perpetually damp or seasonally flooded sites. Identifying and utilizing these specific species is the solution for successfully cultivating areas with poor drainage.
How Plants Tolerate Saturated Soil Conditions
Plants that naturally grow in wetlands or areas with saturated soil possess unique physiological and structural modifications to circumvent oxygen deprivation. One of the most significant adaptations is a specialized tissue called aerenchyma, which forms extensive air channels within the stems and roots. This porous tissue acts like an internal snorkel system, facilitating the transport of oxygen from the leaves and stems downward to the submerged roots. This internal gas exchange allows the root tips to continue breathing even when the surrounding soil is entirely anoxic.
Many flood-tolerant woody plants also develop hypertrophied lenticels, which are enlarged, porous openings on the stem surface. These swollen pores increase the rate of gas exchange between the atmosphere and the submerged plant tissues. Furthermore, many species respond to waterlogging by rapidly producing adventitious roots. These new, shallow roots emerge from the stem closer to the soil surface, accessing dissolved oxygen just beneath the water or soil surface, offering a survival mechanism until the water level recedes.
The lack of oxygen in saturated soil causes a chemical shift, forcing soil microbes to use other compounds for respiration, which leads to the build-up of toxic byproducts. These compounds include reduced forms of iron and manganese, as well as sulfides, which can poison non-adapted plants. Flood-tolerant species manage this challenge through metabolic tolerance, either by sequestering these toxins in specific root vacuoles or by releasing a small amount of oxygen from their aerenchyma-supplied roots. This radial oxygen loss creates a thin, oxidized layer around the root zone, effectively neutralizing the most harmful reduced chemical species.
Groundcover and Perennials for Constantly Wet Sites
Selecting herbaceous plants that naturally inhabit damp environments allows gardeners to transform challenging wet spots into vibrant, thriving ecosystems. For areas where water is constantly at or near the surface, such as pond margins or the edges of rain gardens, certain plants are ideally suited. The Corkscrew Rush (Juncus effusus ‘Spiralis’) and Carex species, commonly known as sedges, are grass-like plants that tolerate standing water and provide excellent texture. Pickerel Weed (Pontederia cordata) is a marginal plant that produces spikes of blue flowers and thrives with its roots in shallow standing water.
For sites that remain deeply saturated and bog-like, plants with a high demand for constant moisture are the best choice. Cardinal Flower (Lobelia cardinalis) is a striking native perennial that produces brilliant red flower spikes and requires consistently wet soil, often found in stream banks and low-lying thickets. Swamp Milkweed (Asclepias incarnata) serves as a host plant for Monarch butterfly larvae and performs best in full sun with perpetually damp to boggy conditions. The Marsh Marigold (Caltha palustris) is one of the earliest spring bloomers, displaying bright yellow, buttercup-like flowers in saturated soil.
Many attractive, ornamental perennials are also surprisingly tolerant of moist, poorly draining soil, making them perfect for damp shade gardens. Astilbe species, known for their feathery plumes, require consistently moist soil to prevent leaf scorch, making them a good fit for damp locations where water doesn’t stand for long periods. Rodgersia, with its dramatic, bronze-tinted foliage and spires of white or pink flowers, thrives in moist shade and can handle wetter conditions than many other ornamental plants. The large-leaved Hosta cultivars are also widely adaptable to damp areas, provided the soil is rich in organic matter.
Durable Shrubs and Trees for Poorly Drained Areas
Woody plants that tolerate poorly drained conditions are invaluable for providing structure, privacy, and long-term solutions for sites with persistent moisture. Deciduous trees like the Bald Cypress (Taxodium distichum), a conifer that uniquely drops its needles in the fall, are highly adaptable and develop specialized root structures called “knees” in flooded conditions. The River Birch (Betula nigra) is another excellent choice, prized for its exfoliating bark and its ability to withstand alternating periods of flood and drought, often found along waterways. Other suitable deciduous trees include the Red Maple (Acer rubrum) and the Black Tupelo (Nyssa sylvatica), both of which are native to swampy areas and offer striking fall color.
Among shrubs, the Redosier Dogwood (Cornus sericea) is known for its brilliant red stems in winter, thriving in standing water and heavy clay soils. Summersweet (Clethra alnifolia) is a fragrant, summer-blooming shrub that prefers moist, acidic soil and can handle periodically wet conditions. For evergreen presence, the Winterberry Holly (Ilex verticillata) is a superb deciduous holly that tolerates wet soil and produces abundant red berries that persist through the winter after the leaves have dropped. Selecting these specialized trees and shrubs can provide significant environmental benefits, including improved bank stabilization and erosion control.