by Matt Latham, RLA, ASLA, LEED AP
Often times, I will be urged (or in some cases even required) by Clients or Government Agencies to specify only native plants when doing planting designs for a project. The reasoning goes that native plants are naturally adapted to the local climate and therefore have a higher likelihood of survival while having less of a need for supplemental watering. While I agree that those are very good reasons to select native plants, my argument back to the Client in this situation is that this kind of restriction is unnecessarily limiting. You see, there are also many good non-invasive non-native plant selections out there that are also well-adapted to the climate and do not require supplemental watering after establishment. In addition, many of these selections have greater ornamental value than the native selections.
The task of selecting native plants exclusively can be daunting, given that commercially-available native plant selections are limited (though this is starting to change with the advent of new nurseries that specialize in these products), and that the very definition of “native” is somewhat fuzzy. For example, how long does a plant have to be established in an area for it to be considered “native?” Is it 100 years, 500 years, or since the retreat of the glaciers? My family has lived in Ohio for three generations. Depending on who you ask I may or may not be considered an Ohio “native.” Also, in this age of hybrids and cultivars, even a species that started out as native may no longer actually be native after being propagated using modern horticultural methods.
Rather than restricting Landscape Architects to selecting native plants only, I think Clients should ask the Landscape Architect to select plants that are non-invasive, drought-tolerant, and climate-adapted. That will achieve the sustainability goals of an exclusively native landscape without unnecessarily restricting plant material choices, while avoiding any argument over what constitutes a native plant. It will also hopefully provide the added benefit of biodiversity, which is something I believe to be essential to the long-term viability of a landscape.
There are, in my opinion, some valid reasons for restricting selections to native plants, in more narrowly-tailored situations. For example, if you want your landscape to establish a connection with the native landscape of your region, to celebrate the unique character of its flora, or to educate the public, then go for it! Or, if you just want to challenge your Landscape Architect a little more, and hopefully pay him or her for the privilege, then go for it! But let’s end the practice of using the “native” buzzword to make ourselves look sustainable, since a landscape does not necessarily have to be native to be sustainable.