The boggiest part of a garden, where water drains at markedly slow rates, can be a sore spot for even the most experienced of horticulturists. Waterlogged substrates are generated by several natural phenomena. These include proximity to a higher water table, the compaction of fine particles, and the lack of subterranean channels for rapid drainage. These can also be zones around leaky, outdoor taps or faulty hoses.
Most plants indeed favor well-draining substrates, which keep their roots exposed to oxygen and free of excess moisture. Situating these in boggy or marshy soils may cause them to rot in almost no time. Fret not, however, as some wonderful exceptions like having wet feet! In wet, oxygen-poor substrates, these plants have adaptations for shuttling oxygen molecules into their roots.
Over time, as their expanding root system creates more channels for airflow, these species may even improve drainage. Perennials that thrive in rain gardens and pond borders are generally recommended for boggy soils. These include water-loving trees, fruiting shrubs, and flowering herbs. Aim to out-plant these once they have produced a network of sturdy roots. Keep in mind that fragile seedlings can easily be displaced or washed away by water flow.
1) Marsh marigold (Caltha palustris)
As its common name suggests, the marsh marigold thrives in marshy or boggy areas, such as damp woodlands, ditches, and fens. This perennial herb has a rhizomatous root system that is well-adapted to lightly submerged conditions. Wet soil is practically a requirement for its extensive spread and rapid growth. A single plant may boast a width of about 18 inches (46 cm) and a similar mature height. A cluster should fill the boggy zones of your garden with vibrant, yellow blooms each spring.
This marginal plant is not actually related to true marigolds. A member of the buttercup or Ranunculaceae family, it produces succulent, deep-green foliage to complement its showy flowers. The blooms are known for attracting hoverflies (Syrphidae), which are drawn to them because their petals possess ultraviolet hues – invisible to the human eye. Once the blooms are pollinated, they develop into seed pods. If conditions are right, the seeds may germinate around existing stands, increasing their density.
2) Swamp milkweed (Asclepias incarnata)
Interested in turning the boggy zones of your garden into a haven for butterflies? Try cultivating a stand of swamp milkweed! This fantastic shrub is a frequent recommendation for wildlife corridors that support the migration of the monarch butterfly (Danaus plexippus). This species feeds on its beautiful mauve-pink inflorescences and may lay its eggs on the surrounding foliage. Thus, the leaves are frequently used as a forage base for caterpillars.
The specialized roots of swamp milkweed have evolved to thrive in low-oxygen environments, such as compact, wet soils. White and markedly thick, these continue to function even if they are exposed to prolonged spells of excess moisture. In fact, this slow-growing plant may suffer when its surrounding habitat dries out. As it is not particularly successful as a vegetative competitor, aim to grow it alongside non-aggressive native plants.
3) Siberian iris (Iris sibirica)
The Siberian iris can turn the boggiest parts of your garden into its most productive zones. Often grown along the margins and borders of freshwater features, this flowering plant favors consistently moist to wet substrates. Its root system is equipped with self-spreading rhizomes, which eventually form extensive networks marked by their colonies of lengthy, sword-like foliage. When they are densely packed, the leaves create a neat, upright bush with a maximum height of 2 – 4 feet (61 – 122 cm).
The floral stalks of mature Siberian irises appear in late spring to early summer. As their showy blooms are developed, these may grow taller than the leaves. The standout petals are typically deep blue to purple, though some cultivars may also produce white, orange, or even reddish hues. Due to its stiff features, this iris is ideal for hedge plantings and for formal arrangements. Low-maintenance, it is cold-hardy to winter conditions in USDA zones 3 – 8.
4) Elephant ears (Colocasia esculenta)
An ideal choice for boggy zones in tropical to subtropical regions, the elephant ear plant is a wonderful perennial with massive foliage. Its leaves are definitely its finest ornamental features as they are well-structured and may be ornately colored. The petioles arise in a rosette formation directly from the plant’s rhizomes, which are well-adapted to moist and wet conditions. Those of mature plants can quickly grow to a full length of about 4 feet (1.2 meters), bearing leaves that measure up to 35 inches long (89 cm)!
Popularly grown for its edible corms, C. esculenta is also known as ‘taro’, ‘dasheen’, and ‘gabi’. A culturally important ingredient throughout its native range, its corms are rich in starch and are frequently perceived as a staple root vegetable. In fact, due to the versatility of the corms as a food source, this plant was likely cultivated as far back as ancient times.
5) Royal fern (Osmunda regalis)
The royal fern or flowering fern can add nuanced texture to the shady, damp parts of your garden. A temperate fern, it can tolerate a wide range of climatic conditions in USDA hardiness zones 3 – 10. Though it does appreciate moderate drainage, its roots can tolerate persistent moisture and may eventually improve the porousness of your soil. Like many other ferns, it favors slightly acidic conditions and appreciates humus-rich and fertile soil mixtures.
Elegant and broad, the complex, sterile fronds of the royal fern are subdivided into pinnae, which are split even further into pairs of bright green pinnules. In contrast, the fertile fronds are tassel-like and are coated in brown spore clusters. As a whole, each frond unfurls to a full length of about 24 – 63 inches (0.6 – 1.6 meters). As more fronds unfurl to create a rosette of vibrant leaflets, they create shade and cover for nearby seedlings and curious critters. Thus, a cluster of royal ferns can open up many micro-habitats for smaller plants and animals.
6) River birch (Betula nigra)
Water-loving trees are some of the best choices for improving the quality of boggy substrates. The river birch, which typically thrives along the banks of streams, is a fantastic species for zones with excess water. One of its quintessential features is the roughness of its papery or flakey trunk. Its root system can tolerate slightly acidic conditions (down to a pH of 4.5). Take note, however, that it will require generous amounts of full sunshine to become well-established.
Also known as water birch, this versatile tree can provide year-round, long-lived interest to sprawling landscapes – particularly those that are exceedingly warm in summer. Heat-tolerant, it can grow quickly to generate a substantial, shade-producing canopy. It reaches heights of about 60 – 80 feet (18 – 24 meters) in optimal environments. Its most successful specimens can live for up to 75 years!
7) Siberian dogwood (Cornus alba)
For winter interest in the marshiest parts of your backyard, try growing stands of Siberian dogwood. This lovely shrub looks particularly dramatic once its leaves have dropped, revealing a network of fiery, deep-red branches. These stand out beneath a fine layer of snow or frozen raindrops to create a highly-textural display unlike any other. Remarkably cold-tolerant, this species is hardy down to USDA zone 3 (up to -40˚F).
Siberian dogwood has the added benefit of producing more ornamental features outside of winter. It is just as stunning once its branches are covered in its deep-green foliage and topped with clusters of cream-colored inflorescences. Its fall fruits, which may remain on the plant until winter, attract a wide variety of birds. Able to grow to around 4 – 8 feet (1.2 – 2.4 meters) tall, it is particularly useful for creating foundation plantings and informal hedges.
8) Corkscrew rush (Juncus effusus ‘Spiralis’)
The corkscrew rush is an eye-catching cultivar of J. effusus, which is commonly known as “soft rush”. As suggested by its common name, its leafless stems grow in a spiral, creating a coiled appearance that resembles that of a corkscrew. With age, the plant’s coils become less compact. They may lose their scraggly form, but the plant itself continues to look somewhat unkempt because the stems stick out in all directions.
Due to its preference for consistently moist to wet conditions, corkscrew rush may be grown along the margins of a pond or in areas with poor drainage and acidic conditions. Ideally, its roots should be permanently situated beneath around 2 inches (5 cm) of standing to slowly-moving water. If they are provided with regular irrigation, they need not be placed in an actual water feature. Hardy to USDA zones 4 and up, this lovely cultivar flourishes in temperate climates.
9) Calla lily (Zantedeschia aethiopica)
Frequently grown as an ornamental plant due to its dramatic, evergreen foliage and its remarkably elegant inflorescences, the calla lily is a wise choice for bog gardens. It grows beautifully in areas with generous rainfall through spring and fall. Its roots should ideally be situated in moisture-retentive substrates or in areas where they can consistently access water. No stranger to having wet feet, this perennial can even be placed directly in the margins of a pond.
The glossy foliage of calla lily is retained throughout the year in USDA hardiness zones 8 and up. Afternoon shade, particularly in summer, may be necessary to prevent the leaves from scorching or drying out. The dark hues of the leaves draw more attention to the blooms – pure white spathes surrounding fuzzy, finger-like spadices. The floral stalks are particularly exceptional as cut, long-lived blooms, so don’t hesitate to brighten up your home by placing a few in a tall vase!
10) Cardinal flower (Lobelia cardinalis)
A recipient of the RHS Award of Garden Merit, the cardinal flower is often cultivated as a pollinator plant because its inflorescences are irresistible to hummingbirds. Bright red and borne on stiff, upright racemes, each deep-red flower measures around 1 – 2 inches (2.5 – 5 cm) long and consists of five lobes. These are attached to a central tube made of fused stamens. The inflorescence stalks may boast heights of up to 6 feet (1.8 meters).
Often found in wetland regions, the cardinal flower favors wet substrates. Its roots require consistent, year-round moisture and should be protected with a layer of mulch in winter. Typically propagated using divisions or planted using its seeds, its young specimens may need some assistance to stay in place. In muddy substrates, placing rocks or sticks around seedlings or cuttings should help!
11) Virginia sweetspire (Itea virginica)
A productive, deciduous species that can form markedly large colonies, Virginia sweetspire can be used to add stability and structure to persistently moist zones. Its root system is known for having dense suckers in streambanks and low-lying woodlands. Despite its tendency to produce dense stands, some of its wild populations are now classified as ‘Imperiled’. Nonetheless, stands that are maintained for ornamental purposes, particularly in bog or rain gardens, can quickly spread.
Able to grow to a maximum height of around 8 feet (2.4 meters), this impressive shrub is set apart by its gracefully arching branches. These are covered in alternately arranged, bright-green, oval-shaped leaves. In late spring to summer, mature specimens produce throes of cylindrical, downward-facing inflorescences. Each of these is packed with an array of fine, fragrant white blooms.
12) Canna lily (Canna spp.)
If your backyard’s bog or rain garden could use some tropical flair, try cultivating a row of canna lilies! These wonderful flowering plants are fairly straightforward to maintain in areas receiving full sunshine and consistent moisture. Their roots thrive when they are generously watered; they may even survive when they are submerged beneath an inch of standing water. Do note, however, that they are prone to rotting upon exposure to cold temperatures.
Many canna lily cultivars, particularly those grouped under the most popular horticultural hybrids, are now recipients of the RHS Award of Garden Merit. These are distinguished by their attractive foliage, which possesses a range of colors (bronze, blue-green, or bright green), and their statement inflorescences. The blooms come in many dramatic hues and pastel tones. The petals of some cultivars, such as the ‘Tenerife’ and ‘Cleopatra’, may even be bi-colored and speckled!
