Seattle’s Department of Planning and Development, along with other government entities in the greater Puget Sound region, is considering a proposal to require that 75% of new plantings be native to Western Washington.
The proposal is at this time just that and is being floated for discussion. It’s being called a draft concept proposal and has not been fleshed out with details. It’s part of a whole set of green code provisions being considered (scroll to the bottom of the linked document for the native plant section). The full text, from a letter to the Washington Native Plant Society, reads:
“Invasive plant species shall be prohibited from a building site. A plan shall be submitted to show that existing invasive species will be removed, and that 75% of all new plantings will be native to Western Washington. Existing native plant life shall be protected whenever possible. Said plan shall be prepared by a qualified professional or generated based upon published recommendations.”
Kathleen Petrie, the Seattle Sustainable Codes Analyst working on the proposal, raised these questions to WNPS:
- For landscaped areas related to new development, is it reasonable and healthy to mandate that all invasives be removed?
- For landscaped areas related to new development, is it reasonable to require that 75% of new plantings be species native to western Washington? Should the percentage be higher or lower?
- Should there be a broader scope of what is allowed vs. only those species native to western Washington?
- From our initial conversation, it sounds as though this requirement would best apply to new development, not landscaped areas that are being altered or replanted?
- Should this apply to all types of development: i.e. small residential, multifamily, nonresidential, etc?
- Should there be a size threshold on the landscaped area when this requirement would be triggered? For example, this would apply to all projects with newly landscaped areas > 5,000 sf.
- Is the qualified professional a reasonable requirement for all designs, or for those above a certain square footage of area?
- There would be exemptions/allowances from this requirement for urban agriculture/personal gardens, as well as specialty uses such as golf courses and recreation fields.
As an organization, WNPS has not yet come up with detailed answers to these questions. They’re important questions, and if the proposal is adopted in some form, the answers will determine both who is impacted by the requirements and the future character of the urban landscape in Seattle. Our members, many living in Seattle and most of whom are rather passionate about our native flora, have mixed feelings. While we strongly support using a diverse selection of native species in our gardens and restoring vanishing ecosystems, some of us question whether this proposal goes too far. It simply may not be practical, either, even if it is desirable from an ecosystem perspective.
On the first part of the proposal, prohibiting invasive species, I think we’re in general agreement. Getting rid of invasives is a good thing. We shouldn’t be planting anything that’s going to spread unwanted into nearby natural habitats and we should be removing these plants as well.
The Washington State Noxious Weed List contains many plants which have been introduced horticulturally that we just shouldn’t be planting any longer. The list includes bohemian knotweed (Polygonum x bohemicum), butterfly bush (Buddleja davidii), common fennel (Foeniculum vulgare), garden loosestrife (Lysimachia vulgaris), purple loosestrife (Lythrum salicaria), Scotch broom (Cytisus scoparius), Himalayan blackberry (Rubus Armeniacus), yellow flag iris (Iris pseudacorus), and dozens more.
But what about native species that can be invasive? Red alder (Alnus rubra) spreads naturally into areas following disturbance, as does black cottonwood (Populus trichocarpa) in moist soils. Neither makes a good street tree: they’re too big when mature and cottonwoods in particular are messy. Snowberry (Symphoricarpos albus) is a wonderful shrub, but it can easily spread and get out of control.
As good as the noxious weeds list is, it doesn’t include all exotic species that can be invasive. Some species are so commonly encountered or are politically sensitive that they’re not included, including English Holly (Ilex aquifolium), European Mountain Ash (Sorbus acuparia), and Cotoneaster species.
Requiring 75% Native Species
In an ideal world we might wish for a return to the landscape that existed on the shores of the Salish Sea before European settlers arrived. Those are the conditions under which the plants we describe as “native” grew. Yet there’s some evidence that Native Americans moved plants around, gardening the landscape to enhance food production. Just where do we draw the line about what is a native plant? For today’s purpose, let’s just say it’s anything that grew here before my white ancestors arrived.
The Puget Trough ecoregion, which is where Seattle thrives today, is characterized primarily by woodland habitats. Douglas-fir (Pseudotsuga menziesii) is the dominant species. Mature old-growth specimens can be over 6 feet in diameter and up to 300 feet tall. Together with western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata), both large trees in their own right, the resultant forest is deeply shaded and generally moist.
I don’t know about you, but I like a little sunshine on short winter days. I love to spend time in the forest. I want to have forested hillsides in my view. But I don’t want to live under a thick coniferous canopy.
Many of our smaller native species evolved to grow in the shade of the conifers, within forest openings, or along the edges. Vine maple (Acer circinatum) is a fine understory tree. It will grow in sunny sites as well. I recommend it highly for west-side northwest gardens. Salal (Gaultheria shallon) is prized in many gardens around the world. Evergreen huckleberry (Vaccinium ovatum) is a great shrub. Kinnickinnick (Arctostaphylos uva-ursi) thrives in both sun and shade, even tolerating parking lot island locations.
What I see in many “native” plantings is a relatively small plant palette, including those species I mentioned in the previous paragraph. Why don’t we see more diversity? Someone has to grow the plants and a nursery has to sell them before they’re going to be commonly planted. Many of our herbaceous perennials adapt to our winter wet and summer dry habitat by blooming in the spring and then going dormant in the summer, disappearing just at the time when people want their gardens to be looking great for outdoor entertaining.
If Seattle ends up mandating that 75% of plantings be native, the whole nursery industry would be upended. Certainly, over time, those businesses would adapt but the native palette available in the nursery trade is unlikely to ever be as diverse as what I’ll see on a leisurely walk in relatively undisturbed habitat on a late spring day. Some plants are just hard to propagate or don’t take kindly to being transplanted.
Brett Johnson, a landscape designer with a focus native plants and wildlife habitat, writes:
Nurseries, both at the wholesale and retail level would be hard pressed to provide the plants needed, regardless of how “native plant” was defined or what list was used.
Far too many native species are considered “weeds” by the average gardener, so that implementation of this kind of thing, even on PUBLIC lands only, would become difficult to enforce with people who actively dislike the plants recommended. This kind of a mandate, in my view, is a recipe for disaster in that it could easily become a “big brother” kind of random imposition that people really hate. I personally think ANY mandate for a percentage of plants is going to be practically impossible to enforce, and not worth the time and red tape needed to deal with it.
Any park with ball fields or play areas would also be difficult to figure out how to administer such a mandate… even with an “ecolawn” that was actually native.
If the stated goal is to get people to plant natives, there are alternatives. Rather than creating an unrealistic mandate that people have to adhere to, even at a lesser percentage, it would seem to me to make more sense to give people something like some kind of tax break based on the percentage of native plants in their garden.
I’m sure that there are other more creative ways to get people to plant more natives, and a larger variety of natives, but as someone that has been selling native plants for years, this is not as easy as it sounds. Far too many of the native plants that would otherwise be perfect for urban gardens are either difficult to grow, on various endangered or threatened species lists (which listed species WNPS has a policy to actively discourage the cultivation of, I might add), or simply not even on the radar as possibilities.
The more i think about this proposal, the worse it seems to me. I would love to say that this kind of thing is feasible, but on so many levels I think it is ill conceived.
In my own Bellingham garden, about 90 miles north of Seattle, we are slowly increasing the proportion of native species. But I doubt that we’ll ever achieve 75% natives, measured either by biomass or number of plants. Brett says he doesn’t have more than about 50% native species on his property and he’s been at it for many years. One of the “native” species in my garden is on the threatened list for Washington, isn’t native to my county, but thrives in my front yard.
Martha Jackson, a Seattle gardener and active WNPS member, writes in her comments on the proposal:
From a homeowner’s point of view, here are some real challenges to landscaping a city lot with natives. Since buying my house in 2004, I have removed many non-native plants from my yard, and attempted to plant only natives. But what native does one plant for an evergreen screen? One does not always have room for another Western red cedar, shore pine, or Douglas fir (I have settled for Myrica californica — which is not native to the Puget Sound Basin).
Seattle’s proposal to require a high percentage of native plants in the urban landscape is laudable in concept, but may not be practical when it comes to implementation. And we haven’t even considered how it would be enforced, what training landscape professionals would need, and whether there’s any money to pay for enforcement.
There’s more discussion of the idea on writer Valerie Easton’s Plant Talk blog a couple of days ago. Linda Chalker-Scott, a Washington State University Extension professional who is in the process of updating a popular reference book on gardening with natives in the northwest, weighed in on The Garden Professors. Bert Cregg, also from WSU, responded a couple of days later in Are natives the answer? Revisited. Even our friends at the Florida Native Plant Society in the opposite corner of the country are talking about what this means in an article titled Are Natives the Answer? Professor Cregg, Why Are You Asking?
Should cultivars of natives be acceptable? Where do we draw the line about what’s native and what’s not? The issue is more complex than it appears on the surface. I’m all in favor of as much native diversity in our built-up habitats as possible. Yet I don’t think a mandate of a specific native plant percentage is the way to go.
What do you think? Should there be a mandate for a high percentage of native species in the urban, built environment? How detailed should the requirements be? How could such a requirement be implemented on a practical basis? Might a carrot be better than a stick? Share your comments here, or weigh in directly with Kathleen M. Petrie at the City of Seattle, Department of Planning and Development.
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