Streams, ponds, wetlands
Protecting our water
If your property includes a wetland, such as a permanent or intermittent stream or river, or a pond or a lake, or a swamp or a marsh, it is important to protect water quality by providing a buffer of native plants between the wetland and any developed area including mown lawn. Ideally, that should be at least 100 feet wide, though any buffer is better than nothing.
However, PLEASE NOTE! If the wetland is already buffered by natural vegetation, it is our job to control invasive plants, and we should avoid adding new species, as that will disturb the existing plant community. Be a good steward by letting the native plants and wildlife sort themselves out the way they have been doing for thousands of years. But if you have been mowing down to the edge of a stream or a pond, why not stop mowing and fill the area with native plants? Try to choose ones that normally would be there - see below for guidance. By planting combinations that occur in nature, you are more likely to be creating real habitat in which the complicated interactions between flora and fauna can play out.
Properties that include streams are the last bulwark against the damage inflicted by runoff from impervious surfaces. This “riparian buffer” captures and cleans stormwater runoff that can erode the banks and flood the streams. That floodwater carries tons of sediment down to the Chesapeake Bay, where it buries the sea grasses that are the basis of the ecosystem there. In addition, healthy streams need to be lined with trees to keep the water temperature cool and to provide leaves to feed the underwater ecosystem. The Commonwealth has a brochure on this subject.
Before you think about adding more, try to identify the plants that are there. Natives worth keeping may already be growing there. Don't make the mistake of taking things out that you may later discover are valuable natives! Apps such as iNaturalist can help, and you can also invite an Audubon-at-Home Ambassador to take a look.
Do you need a permit?
Land-disturbing activities are prohibited within floodplains or within 100 feet of a stream, shore, or wetland, whether the land is publicly or privately owned, unless you obtain a permit. (“Land-disturbing” includes removal of vegetation and planting new plants.) Maps of these “Resource Protection Areas” can be found here.
The spreadsheet below of plants that are currently available for sale can give you guidance about which native plants to choose. There are two reasons to give this thoughtful consideration.
How wet the soil is will determine which plants will flourish.
Restoring a functional ecosystem means combining species that normally live in community and thus support the complicated web of associated animal species. Biodiversity includes not only many plant species but also a variety of heights - canopy and understory trees, shrubs, and the ground layer.
Along streams, there are plants that live on the side of the banks where their roots have good drainage but there may be occasional flooding. In the lower reaches of streams, the next zone is floodplains - the soil is saturated intermittently - or swamps or marshes with permanently saturated soil. Upstream, smaller streams that never jump their banks do not have floodplains (or only have tiny areas within the banks) but are simply buffered by woods. It is ideal to determine the plant community type of nearby woods to guide your planting decisions. But if you are planting a riparian buffer near a stream or pond that has minimal floodplain (and no bordering swamp or marsh), choosing plants from the Mixed Mesic plant community would be a good guess.
Ponds and lakes in Northern Virginia are human-made creations, so there is no local natural reference. You can use the same scheme as for streams plus add marginal plants - ones that actually grow in the standing water.
In all cases, also check the light requirement for each species.
Marshes are sunny wetlands, swamps are wooded.
If your property is in a tidal area, or includes a seep or bog, note the column for that. Wetlands are precious. Please consult an expert in plant communities before attempting to “help” them.
This is a very big spreadsheet. To open it in Google Drive or download it from there, click here. The term "forb" is what gardeners know as perennials and annuals (most of these are perennial.)
Looking for design ideas?
Maryland’s Department of Natural Resources has posted planting plans for 24 “buffer” gardens, from small to large.