A collaborative effort to halt invasives

Anyone who’s ever maintained a landscape knows that, unless the correct plants were selected during the initial installation, all the care in the world won’t make them perform properly. Fortunately, most landscape professionals recognize that it’s important to choose plants based not only on appearance, but also on the site’s climate, size, soil properties, sun/shade levels, etc. There’s now another critical question to ask when specifying landscape plants: “Are any of these plants invasive?”

Photos courtesy of PlantRight.
Members of the PlantRight steering committee work closely together to study and identify those plants that are invasive. The group has created an interactive Web site that lists not only invasive plants, but also non-alternatives that look and perform similarly. PlantRight urgers landscapers and gardeners to voluntarily consider using Scotch Broom alternatives such as Magical Golf Forsythia, shown here.

Invasive plants can wreak widespread environmental damage (in addition to choking out individual residential landscapes). From displacing native plants to threatening wildlife habitat to increasing fire danger to altering entire ecosystems, the consequences of invasives can be seen in nearly every part of the country.

In some areas, governmental agencies have begun to crack down on the use of invasives, but in California, a diverse group of environmental advocates, academic researchers and green industry representatives has come together to try an approach they hope will be more effective than regulation: namely, education.

PlantRight ( was created by the California Horticultural Invasives Prevention (Cal-HIP) partnership to help protect California from invasive plants by identifying those that are being horticulturally introduced, and then offering suggested alternatives. Terri Kempton, from the San Francisco-based environmental nonprofit Sustainable Conservation, manages the Cal-HIP steering committee, a group that includes representatives from the California Landscape Contractors Association, the American Nursery and Landscape Association, the California Association of Nurseries and Garden Centers and the California State Floral Association, along with landscape architects and designers, as well as those from environmental and academic communities.

The partnership effort started in 2004. “We knew that some other approaches that had been tried hadn’t really been effective,” Kempton explains. “Regulation is very costly to enforce, and by its very nature often doesn’t take into account the needs of businesses, and grassroots efforts from environmental groups had tended to create a lot of antagonism. We saw an opportunity for many parties to work together in cooperation, to look for solutions that are good for the environment and good for businesses.”

The beauty of Scotch Broom (Cytisus scoparius) is evident, but the damage the invasive plant can do to natural ecosystems isn’t as pretty.

It also makes good financial sense: California is spending, conservatively, $85 million a year trying to control and eradicate invasive plants. “It doesn’t make any sense spending so much money and energy trying to remove invasive plants from the environment while also having them for sale in stores so people can re-introduce them,” says Kempton. “It’s one of those situations where the right hand wasn’t really talking to the left hand. So, we thought it made more sense to bring everyone to the table, identify which plants are invasive and identify some good alternatives for people to use instead.”

Part of the challenge is to simply make people aware that landscape plants are an integral part of the invasives problem. “I think sometimes when people hear about invasive plants they think only about plants out in the wild—in natural lands—and involve what would typically be called weeds,” says Kempton. “What people may not realize is that more than half of those invasions began with garden or landscaping plants.”

That’s why PlantRight has focused its efforts on plants that are being horticulturally introduced. “We’ve targeted those plants that are being introduced 100 percent by human choice,” says Kempton. While there are many damaging invasive plants that have been introduced accidentally-for example, by seeds transported on vehicle tires or shoes—tackling horticulturally introduced invasives provides a manageable approach to the issue. “This is a problem we can do something about,” she says. “We were picking these plants not knowing they were invasives. They had characteristics we liked. They’re vigorous, they’re drought-tolerant, they perform well, but now we know they’re invasive, so if we just make different choices then we will have eliminated a huge environmental problem. It’s one of those areas where we can make a different and it’s very tangible.”

The group spent a significant amount of time initially just studying and determining scientifically studying which plants are invasive. “A lot of times it involves anecdotal evidence. We really needed to find a scientific way to identify what is invasive,” says Kempton. Unless everyone on the steering committee signs off that a certain plant is invasive, it isn’t added to the PlantRight list. “If there’s something about a certain plant that we don’t fully understand, we don’t move forward on it,” she adds. “For example, there are some forms of ivy that are causing tremendous problems in wild lands, but if we can’t identify exactly what type of ivy is causing the problem, we don’t want to step forward with erroneous information to tell the industry to stop selling it.”

This careful approach ensures that once the group has identified a plant as invasive, there’s total group support for efforts to caution against its use. Currently, that list includes 19 different invasive plants. “All of the invasives on our list have some sort of built-in advantage, so when they’re introduced into an environment they’re able to outcompete the native plants,” explains Kempton. “Sometimes things don’t seem to be a problem in a given yard, but their seeds show up miles away and they become a problem there. Gardeners have to realize that they are gardening not only for their yard-they’re gardening for a much larger area.”

An invasion of Periwinkle (Vinca major) in the wild lands of California. PlantRight recommends the Geranium as a non-invasive alternative to Periwinkle.

With an estimated 600,000 different types of plants available in California, there are still plenty of alternatives to using the relatively few invasives. After years of behind-the-scenes work and research to identify both invasives and alternatives, in March 2008 the group began a massive public outreach effort. In addition to coverage in the state’s largest newspapers and on National Public Radio, PlantRight has given presentations to landscaping and horticultural groups throughout California and produced brochures explaining the issue of invasives.

Perhaps the most important communications tool is the Web site, which includes interactive features that allow visitors to see clear photos of individual invasive plants, as well as possible alternatives that look and perform similarly, but which are not invasive. “We wanted to provide suggestions for plants that are beautiful, have similar characteristics and yet which are not going to get out in to wild lands,” says Kempton. It was important to the group to make information about alternatives available, and to make it easy for homeowners and professional horticulturists/landscapers/retailers alike to understand.

She says that people have really responded to the message. “Nobody wants to be causing a problem, nobody wants to be the bad guy,” says Kempton. “Nobody wakes up in the morning and says, ‘I just absolutely have to have Scotch broom in my landscape.’ What they really mean is, ‘I want a great, vigorous shrub with yellow flowers.’ Fortunately, there are lots of them.” The group’s Web site lists alternatives on a regional basis, taking into consideration California’s vastly different climates. This allows users to see what plants are causing problems in their area, as well as alternatives that will do well in that zone. “It gives people a chance to be creative, and to think more carefully about their plant choices,” she explains.

PlantRight will be preparing a case study summarizing its efforts and their effectiveness, hoping to share information with other states that may be contemplating a similar approach to combating invasive plants. “Invasives aren’t just a problem in California. We feel we’ve made some good headway and if other people would like to use our process or learn from our materials, we’d like to partner with them to make that happen.”

To be truly effective, other states and regions would do well to follow PlantRight’s lead in bringing plant growers, retailers, designers and landscape installers into the process. “We feel that finding voluntary solutions will make a big impact, and it gives businesses an opportunity to be proactive and step forward to be the good guys,” says Kempton. “I’m so proud of how people have worked together. It’s such a great way to make a lasting change. It gives us a chance to be proactive, and keep invasive plants from being introduced in the first place. It’s much better than waiting for regulations to come-at that point it means the situation is out of control and we’re in trouble.”

Patrick White is a freelance writer and editor who is always on the lookout for interesting and unusual stories.