Reed Bed Design

When the term "Reed Bed" is discussed, are we talking about a polyculture? Are there a wide varieity of plants that can thrive in this environment (zone 6). Also, can a similar bed be created from road runoff?

Hi Adam,

There are three main type of treatment wetland for septic tank effluent:

Soil based constructed wetlands - which are usually a relatively diverse polyculture of Phragmites australis (common reed), Typha latifolia (cat-tail or bulrush), Iris pseudacorus (yellow flag), Sparganium erectum (branched burr reed) and other lower species.
Horizontal flow gravel reed beds - usually dominated by Phragmites, since that's the plant that grows best and sends down good deep roots into the water column in the gravel. Often with Iris and Mentha for aesthetics.
Vertical flow gravel reed bed - also usually dominated by Phragmites.

For road runoff the soil based systems are best because they won't clog up with grit over time. Also, the cleaner water helps a more diverse flora to thrive, whereas richer sewage systems tend to push the most vigorous species to the fore, and the others suffer.