Choose reed bed plants that tolerate permanently wet roots, high nutrient loads and your winter, and the parent page names four: common reed (Phragmites), cattail (Typha), yellow flag iris and bulrush (Scirpus). Plant the species that already grows wild in your own marshes, keep aggressive spreaders out of natural waterways, and do not eat any part of a plant that has grown in greywater.
Part of Greywater Recycling Systems
Plant selection for a reed bed means picking wetland species whose roots can stand in water all year and carry oxygen into gravel, whose growth habit suits a small managed bed, and that survive the local winter.
What A Bed Plant Must Do
- Live with roots wet all year. Gravel in a reed bed is saturated at the bottom.
- Take up and live on a high nutrient and soap load.
- Put oxygen into the root zone, the reason wetland plants beat ordinary garden plants in the bed.
- Survive winter, at least with roots below the frost line.
- Not escape. A plant that spreads by rhizomes and seed can leave the bed.
The Four Plants The Parent Page Names
| Plant | Parent page’s notes | Extra cautions |
|---|---|---|
| Common reed (Phragmites) | Tough, aggressive grower, excellent water treatment | Aggressive means it can spread; in some regions the local form is invasive, so use native stock and contain the bed |
| Cattail (Typha) | Edible roots, good treatment capacity | Do not eat roots, shoots or pollen from a bed that receives greywater |
| Yellow flag iris | Ornamental and functional | All parts are poisonous if eaten, as I recall |
| Bulrush (Scirpus) | Hardy, good cold tolerance | Check local species; some are weedy |
Choosing For Your Site
- Use what grows nearby. Dig a few clumps from a local ditch or pond margin well away from any fouled water; local stock is already adapted to your winter.
- Match the winter. Bulrush is the cold-hardy choice (parent page). Reed beds go dormant in winter but survive if the roots lie below the frost line.
- Mix species so the bed is not wiped out by one pest or one hard winter.
- Plant when roots can establish, and feed the bed clean water until they do, before the greywater arrives.
Managing The Bed
- Thin and harvest each season, composting the biomass away from food beds (parent page).
- Watch for spread at the edges and cut or dig out strays.
- Don’t plant the bed’s cuttings in food gardens or near natural water.
Common Mistakes
- Planting dryland ornamentals in the bed. Their roots rot in saturated gravel.
- Eating the “edible” cattail. Plants take up what the water carries, including organisms.
- Planting reeds beside a stream where seed and rhizomes can reach it.
- Planting too late, so the bed carries water before the roots can treat it.
Safety
Plants grown in greywater can carry organisms and chemicals, and some bed plants are poisonous
Do not eat any part of a plant from a greywater bed, and do not feed it to animals. Yellow flag iris is poisonous to eat. Wash hands after handling the plants, and keep children out of the bed. Keep the bed’s pipes apart from drinking water (Plumbing Separation).
What’s Next
- Learn next: Bed Construction — build the bed the plants will fill
- Combine with: Constructed Wetlands & Reed Beds — how the plants and gravel work together