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Public Radio's Environmental News Magazine (follow us on Google News)

Cultivating Weeds

Air Date: Week of

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Gardeners all across the country are coddling invasive plant species in their yards. Science News Science Editor Janet Raloff talks with host Steve Curwood about why escapees from home gardens are a problem for wild lands.


CURWOOD: No one wants to aid and abet an invading army, but across the nation, American gardeners are unwittingly harboring, even coddling, horticultural terrorists in their own backyards. Gardeners frequently choose inappropriate plants for their region and their yard's growing conditions without realizing they could be promoting the spread of invasive species. Janet Raloff details the dilemma of cultivating weeds in Science News. Hi, Janet.

RALOFF: Hello, Steve.

CURWOOD: I was shocked to find out that I'm in trouble when I grow Bachelor Buttons.

RALOFF: I was shocked to find out that I'm in trouble with most of the plants I purchased last year.

CURWOOD: Why does it matter what happens along one family's sidewalk, in one family's garden, for instance?

RALOFF: The real problem is when these things spread into areas where there are no people around to weed them out. We're talking about wildlands like National Parks or wetlands or prairies or deserts. And when these plants take over there, they can ride roughshod over the local native plants, either killing them, or taking the water that they had ordinarily depended upon, or shading them to such an extent that they die from lack of light. It's become a real problem.

For example, locally at Rock Creek Park, which is a small National Park in Washington, D.C. It now has 238 invasive species, and most of these are plants that have escaped from local gardens in Washington, D.C. Right now the National Park Service spends close to a quarter million dollars a year for this very small park, just trying to manage invasive species. It can't even begin to deal with the problem nationally.

CURWOOD: Well, let's talk about some of these chlorophyll-filled criminal types. Who are the really bad boys of this list?

RALOFF: Well, you'd like it if there was like a ten most wanted list. But in fact, the ten most wanted list is going to be different for New England, where you are, than for the mid-Atlantic states where I am, or from the mid-West where I grew up, or from California drylands. There are several plants that are probably a problem for everybody. Norway Maple and Tree of Heaven are good examples. But a lot of these things are rather site-specific, and we just have to be diligent and watch how plants are behaving in our own particular yards.

CURWOOD: Give me a couple of other examples, Janet, of some plants that we can find for sale in nurseries and are flourishing in backyard gardens that are also on this invasive species list.

RALOFF: Well, some of the more popular ones in the local nurseries around here are like Burning Bush, which is also known as Winged Euonymus. There's also the Butterfly Bush. There's the English Holly, European Privet, Ornamental Figs, Japanese Honeysuckle, Multiflora Rose, Norway Maple. In the mid-West, English Ivy is a big problem, so is the European Buckthorn. It's a real problem in the prairies there, which are having a hard time surviving anyway.

In the Southwest you have some grasses that are going into deserts, and it's causing fire hazards where there had never been one before, and it's killing off cacti. In other areas, you've got sunflowers that were from--they initially evolved, anyway, in the plain states--and now they've crossed with other sunflowers in Texas and Oklahoma and become incredibly invasive.

CURWOOD: So, what are the warning signs that your garden might be home to invasive species?

RALOFF: One sign is that you get plants popping up that you didn't, in fact, plant. Or you may find that some of your plants are producing more seeds than usual, a lot more seeds than usual.

CURWOOD: Now, what about the Bachelor Button? One of the reasons that I like it is that, well, let's face it, it's really easy to grow.

RALOFF: Well, that's one of the warning signs, too, of plants that can behave badly. From an invasive species point of view, horticulturists would prefer that we put plants in our yards that really take a bit of coddling, so that they won't start spreading willy-nilly on their own if they get released into the wild. In fact, that's exactly the opposite of what a gardener wants. We want a plant that takes no maintenance and grows easily on its own. So, you run into that conundrum.

CURWOOD: What can gardeners do?

RALOFF: The first thing is become aware that we potentially can be part of the problem. I think then, after that, you have to sort of lower your expectations and realize that you probably can't have just any plant because it's pretty and you can afford it. You have to be responsible. If you don't know what plants are invasive in your area, it pays to buy from experienced nurseries. You also have to start scouting your yard periodically for invaders from somebody else's yard, and make sure that you evict these bullies as soon as you can. And then we just have to stay diligent because there is no one-stop shopping to find a list of all the invasive species in your area or anywhere. You have to make the effort to find out, you know, sort of stay on top of that list, but realize it will never be up-to-date. Certain plants will continue to become invasive this year and take years to make it onto the list.

CURWOOD: Janet Raloff is senior editor at Science News. Thanks for filling me in on your article, Janet.

RALOFF: My pleasure, Steve.

[MUSIC: Various Artists - Kwaito Hits - EMI (2001)]



Janet Raloff’s article in Science News

Additional info on invasives in yards and gardens


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