Knowledgebase
Native ground cover for a RainScapes erosion mitigation project #749892
Asked May 14, 2021, 10:53 AM EDT
Montgomery County Maryland
Expert Response
Hello Liz,
There are several factors which will influence which alternatives would be the best choice - summer sunlight levels, issues with deer browsing, soil drainage (aside from the water flow causing erosion), and any limitations on mature size (height, width).
Given the landscaper's suggested plant, Tiarella, we surmise this area is wooded (or shaded by the house) and generally evenly moist - conditions Tiarella prefers. They are only in flower for two or three weeks in mid-spring. Given the desire or requirement for the project's plantings to be native, the landscaper is likely using flowering plants as they will have the greatest benefit to wildlife.
Maryland has few native conifers, especially outside of our westernmost mountains where the temperatures are cooler and soil very well-drained - preferred conditions shared by many conifers. If the site were sunny, you could use any of a handful of cultivars of ground-covering forms of Common Juniper (Juniperus communis) or the low (but not ground-hugging) forms of Eastern Redcedar (Juniperus virginiana). For part shade, Hemlock (Tsuga canadensis) is quite tolerant and has several dwarf, shrubby forms, but they are vulnerable to the serious pest Hemlock Woolly Adelgid. We are not aware of any ground-covering Hemlock cultivars, however. Similarly, other species that occur in MD (though very rarely in the wild) also prefer full sun and do not have ground-covering forms, only dwarf shrubby forms; these would be Eastern Arborvitae (Thuja occidentalis) and Atlantic Whitecedar (Chamaecyparis thyoides).
Non-conifer, non-flowering candidates are essentially limited to:
- grasses and their cousins sedges and rushes (all of which technically do flower, but not in the stereotypically showy manner)
- ferns
- horsetails (Equisetum)
Horsetails and some fern species can spread aggressively if conditions appeal to them. Few ferns are evergreen, and those that are tend to be a bit disheveled-looking by spring until new growth emerges. Within grasses and sedges, a few are adapted to woodland conditions (since most grasses need sun):
- River Oats (Chasmanthium latifolium) - they can spread aggressively as well, which while good for covering a large-scale area, may be a nuisance for nearby garden beds
- Blue Wood Sedge (Carex glaucodea), Pennsylvania Sedge (Carex pensylvanica), and Spreading Sedge (Carex laxiculmis); though grass-like, they don't form a contiguous lawn like turf grasses do
- Deertongue grass (Dichanthelium clandestinum)
The Contact Us page for the MD Native Plant Society lists a few email addresses - https://mdflora.org/contact_us.html
Miri