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Improving Wet and Boggy Landscapes
Choose the right trees and shrubs, plant high, and improve drainage for success in landscape planting beds with wet or boggy soils. Adopt these strategies for coping with wet locations.
Poor Drainage and Landscape Plantings
Installing Drain Lines
It’s best to plant trees and shrubs that naturally grow well in very damp, wet, or marshy conditions. If your heart is set on a favorite that prefers dry soil, there’s two options:
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- Improve your site’s drainage, or
- Add quick-draining fill before planting and raise the bed higher than the surrounding soil.
Assuming that another area is lower than the soggy planting bed, instal drain lines to solve all its drainage issues.
These are called surface drains. They’re shallowly trenched—usually only 12–14 in. (30–35 cm) deep—and use perforated 4-in. (10-cm) PVC pipe to carry water away to daylight or the street.
Each pipe section is wrapped in a root-barrier sleeve of porous, non-woven fabric tubing material, available from hardware, home, and irrigation retailers.
The wrapped pipe sets into the trench—perforation-holes down—with T-connectors between each section of the drain line. A surface riser and grate fitting completes the main drain line line.
Install lateral lines in the same manner. The drain field should covers the entire planting area, spaced 4 ft. (1.2 m) apart between drain lines or surface drains.
Water that collects on the surface will flow into the surface drains, while water beneath the surface will flow into the pipes through the perforations and away from the planting beds.
Improve Wet Sites with Surface Fill
Adding fill of sand-loam mix over the surface is a quick fix for low spots that collect water in a landscape.
Mound up the soil of the bed 12–14 in. (30–35 cm) to keep trees and shrubs above the water so they can establish dry surface roots. Over time, they’ll also tap down into the water below.
Many landscape experts and horticulturists now recommend planting trees and shrubs on low mounds above grade. Surface plantings root in native soil rather than wrap and girdle in holes dug beneath the surface grade.
A wet site is ideal for this approach and is much easier than installing surface drain lines. Adding sand and organic material to existing soil is also a good way to ready the bed for shrubs and a few, water-tolerant trees.
Best Trees and Shrubs for Wet Landscapes
Best Trees for Wet Gardens
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- Alder (Alnus sp.)
- Bald Cypress (Taxodium distichum)
- Dawn Redwood (Metasequoia glyptostroboides)
- River Birch (Betula nigra)
- Tupelo (Nyssa sylvatica)
- Willow (Salix sp.)
- Witch Hazel (Hamamelis sp.)
Best Shrubs for Wet Gardens
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- Bush Cinquefoil (Potentilla fruticosa)
- Fetterbush (Leucothoe fontanesiana)
- Sweet Pepperbush (Clethra alnifolia)
- Sweet Shrub (Calycanthus sp.)
- Virginia Sweetspire (Itea virginica)
- Winter Hazel (Corylopsis sp.)
Best Ferns for Shade and Wet Landscapes
Nearly all ferns are well suited to evenly damp or wet locations in the landscape, but perform best in shady or partial-shade spots. Some deciduous ferns die back during warm weather, but return when temperatures cool and rains begin in autumn.