What is -- or is not -- a weed?

Picasso would like my garden right now; it’s at the height of its Blue Period. Little blue scilla is blooming everywhere. In the largest and longest flower bed, where the daffodils are over, it is the whole show. And I have never planted it; it’s an all-volunteer army of flowers.

In fact, blooming scilla, often called bluebells, are all over the neighborhood. They grow in the company of dandelions in the alleys, and even through ivy on a neglected hillside.

I adore this little plant, but scilla has as many enemies as friends. Some gardeners despise its exuberance and disorder and work to extirpate it by digging up every bulb they can. They consider it a weed.

This raises the age-old question about what is or is not a weed. The answer is in the eye of the beholder. For gardeners, a weed is simply a plant that is growing where it’s unwelcome. 

Value judgments vs other ways of classifying plants

The value judgments we make about which plants are prized, which are accepted, and which are reviled are just that – value judgments, or aesthetic judgments. In the plant caste system, the common, the free-flowering, and the traditional are often valued less than the rare, the hard to grow, and the new (and now often patented) hybrids.

But there is another way of classifying weeds that addresses the more consequential question of whether they are invasive non-native plants that are harmful to local ecosystems, fish and wildlife habitat, and agriculture.  See the Washington State Noxious Weed Control Board site for details.

Tansy Ragwort

You may have heard of tansy ragwort, which is poisonous to cattle, horses and other livestock. It’s a sneaky poison. Cattle who consume it show no symptoms until they suddenly drop dead from liver failure. Our county Noxious Weed Control Board used to be led by a man whose job, when he was a teenager, was to bury the cows that died from it. He definitely had a passion for his career.

Tansy is thought to have been brought to Washington on ships or in imported hayseed. But about half of all invasive plant species are escapees from gardens. The most common of these is Scotch broom. But there are several plants that are still common in local gardens that are invasive and harmful. Butterfly bush, for example, spreads seeds over long distances, and can crowd out native plants along streams, replacing plants local insects, birds and other wildlife need. It’s best to get it out of your garden, but if you can’t or won’t, you can prevent harm by cutting off faded flowers before they go to seed.

Ivy

Ivy is another nemesis of local ecosystems. Birds eat its berries, then poop them out in the woods, where ivy carpets the ground and climbs and smothers the trees. Priest Point Park is a demonstration of this. Like butterfly bush, we shouldn’t grow it, but if we do, (and I confess I have some in my back yard), we must be vigilant about not letting it make berries. I am glad to say mine never has.

Some believe the best way to stop the spread of invasive species – and to conserve water – is to only grow native plants.  That’s commendable, but I can’t bear to give up the flowers and shrubs of my childhood. Gardening, like cooking, is an essential part of our culture and heritage, and that deserves conservation too.

And in case you were wondering, the free-flowering scilla isn’t native, but it’s not invasive. It’s just enthusiastic. Or, as one member of a handy Facebook group called “Weeds of the Northwest” suggests “spready.”

Jill Severn writes from her home in Olympia, where she grows vegetables, flowers and a small flock of chickens. She loves conversation among gardeners. Start one by emailing her at jill@theJOLTnews.com