Heather Brady, Project Coordinator - California Invasive Plant Council
( If you are reading this anywhere but my blog, you can find the original post here. )
Most of us gardeners are aware of the concept of invasive plants. We see periwinkle (Vinca major, Vinca minor) blanketing whole swatches of our parks and shaded open spaces, we see yellow starthistle (Centaurea solstitialis) running rampant in the dry, sunny open spaces of the Northstate, and we instinctively know that these plants must be damaging the existing environment. While I don’t know of any gardener or nursery that would suggest planting starthistle, plenty will still recommend planting perwinkle. Therein lies just one tip of the confusing iceberg that is the “Invasive Plant” issue for gardeners: What is invasive for my region? What is invasive for other regions? And what of those latter should I be concerned about anyway? What’s the difference between a good, solid garden thug that holds its own and an environmentally damaging invasive plant? Photo above: Ornamental Deer Grass (Muhlenbergia rigens) makes a very nice, showy alternative to invasive grasses such as Pampas Grass (Cortaderia jubata).
That’s where we California gardeners are lucky (one of the many ways we’re lucky): we have the California Invasive Plant Council (http://www.cal-ipc.org/) also known as Cal-IPC (pronounced cal ipsee) to help us navigate the invasive plant issue. I recently spoke at length with Heather Brady, Project Coordinator for Cal-IPC about the Council and their upcoming annual Symposium being held in Chico October 2-4th. Photo above: Invasive periwinkle has taken over this roadside verge.
Founded in 1992, the council started as an informal group of “weed-workers” from throughout the state who had the foresight to understand that they could work more efficiently and successfully at managing/eradicating noxious weeds by pooling their individual knowledge and experience. Since then, the council has grown to become a leader in invasive plant issues in the state. One of their early volunteers, Dough Johnson, became their first paid staff member and is now the Executive Director. A registered 501(c)3, Cal-IPC has a small paid staff, legions of volunteers and over 1000 members across the state, who receive the council’s quarterly newsletter and regular email updates. (For individual membership visit the website: http://www.cal-ipc/about/membership/index.php). Photo above: Invasive yellow starthistle is rampant in dry, sunny open areas of Northern California.
Perhaps most importantly to those of us home-gardeners who are interested, Cal-IPC has an excellent website with resources for us about invasives in general, as well as those specific to our region. Two crucial projects of the council are the Don’t Plant a Pest! brochures, and their involvement in the PlantRight initiative (www.plantright.org). Both projects provide regionally specific information about plants known to be invasive in that region as well as offering several suggested horticultural alternatives to that invasive plant, with cultural and zone information on the alternative. For instance, if you were looking for a low-care ground cover for dry shade, Cal-IPC’s Central Valley version of the Don’t Plant a Pest! brochure would let you know that Vinca major is a pest and smothers the native plant community, but that Pachysandra (Pachysandra terminalis) or a prostrate variety of the native California Lilac (Ceanothus species) would be good alternatives. The website also lists plants on the secondary noxious weeds list and those that are being researched as potentially invasive – such as Cotoneaster species (Cotoneaster franchetii, C. lacteus, and C. pannosa). Photo above: Native California grape is a nice alternative to invasive vines such as Himalayan Blackberry.
Invasive exotic plants versus native plants has been a bit of a theme in the garden press this year with books such as “Bringing Nature Home” by Douglas Tallamy (Timber Press, 2007 ) and “Native Alternatives to Invasive Plants” by C. Colston Burrell (Brooklyn Botanic Gardens, 2007). But even from these outstanding horticulture presses, confusion remains. Listed in the BBG All-region guide, you will find varieties of rose, oak, nandina, buddleia and foxglove. Cal-IPC database can help us to determine the risk these plants hold in our specific areas.
When I asked Heather about Cal-IPC’s official position on what we as gardeners should do about plants that are not invasive for us, but which might be invasive in a region adjacent to us (so say, the foothill and mountain or coastal regions near us in the Central Valley or vice versa), she said while they did not have an official response, the council hoped that with the resources for all regions being available on-line, gardeners, nurseries, and growers would be able to access the information and make decisions that consider our role in protecting California’s wildlands. Photo above: Deer Grass (Muhlenbergia rigens) forms an almost formal hedge along the pathways of the McConnell Arboretum and Gardens at Turtle Bay Exploration Park in Redding.
I come to the subject of invasive garden plants with some personal experience. Years ago, I knowingly planted true Queen Anne’s Lace (Daucus carrota) in my Colorado garden. Fairly well-documented as at least a secondary noxious weed, I loved the flowers, which reminded me of summers in Rhode Island. How bad can it be? I thought. I planned to pick all the flowers for cut flowers anyway. Famous last words. I have acute gardener’s remorse to this day because this one plant in a two inch pot went so wild in my arid, dry garden – and driveway – and neighbor’s garden. I spent hours a week removing flowers and seed heads trying to control it. Photo above: The culinary forms of Fennel can be a good alternative to Queen Anne’s Lace (Daucus carrota), an invasive weed in many states.
As a gardener, I do not like to be lectured at. We all make our own paths to our own gardens. But nor do I like to be plain foolish (as in the case of the Queen Anne’s lace) or misled, as in the case of nurseries and plant websites continuing to make statements such as: “Periwinkle makes a great easy care ground cover in shaded areas. If its invasiveness bothers you…” If it bothers me? It better bother me if what I am planting on recommendation from an expert is actively harming the world around me. I am big believer in the idea that gardening is like doctoring, the first rule should always be: Do no Harm….this does not mean I cannot kill a plant that’s not working for me, or that I can’t knock down the unbearably ugly cement-block barbeque pit in my yard from previous owners. It does mean I have a responsibility to the larger natural world. Cal-IPC makes it easier for us to stay on top of this particular responsibility. Photo above: Short spreading varieties of California Fuschia (Zauschneria californica) are slow growing but effective ground covers for dry, sunny areas.
Central Valley Plant Right Brochure:
plantright_alternative-plants_central-valley
And some Direct Links:
1. Direct link to the PDFs of the Invasive Plants of California’s Wildlands
http://www.cal-ipc.org/ip/management/ipcw/online.php
2. Plant Profiles, very similar to above, but have more references to scientific papers, Cal-IPC’s Quarterly Newsletter, and a greater diversity of plants
http://www.cal-ipc.org/ip/management/plant_profiles/index.php
3. Direct link to Cal-IPC Plant Inventory, where we collaboratively assessed the Impact, Invasiveness, Distribution, and Documentation Level for over 200 plants:
http://www.cal-ipc.org/ip/inventory/weedlist.php
4. Statewide maps that indicate where invasive plants are currently located, if their populations are spreading, and how susceptible un-invaded area are:
http://www.cal-ipc.org/ip/mapping/statewide_maps/index.php
Here is an example of Moderate invasion in Butte County which is spreading: Tamarix
http://www.cal-ipc.org/ip/mapping/statewide_maps/Tamarix_ramosissima.php
Example of currently not invaded in Butte County, but Moderate potential to spread there:
http://www.cal-ipc.org/ip/mapping/statewide_maps/Cortaderia_selloana.php