Identifying weeds: Friend or foe?


Lady’s Thumb (Persicaria maculosa), a member of the knotweed family is very invasive.

It’s happened more than once. I’m scrutinizing a young plant trying to identify friend or foe, and blaming my horrible memory capacity for not remembering the details better. Then in a couple weeks I have this huge, unsightly monstrosity overtaking a garden bed. Or worse, a friend asks, “Is that a weed?”, and I blithely say, “Oh no, that’s a keeper”. Then she calls me to say it has choked out every other plant near it and given her child a nasty rash.

One of my gardening mentors, Marlin Sachtjen, told me that a weed is a plant that you don’t want in your garden because it is ugly, invasive or you just don’t want it. So I’ve had run-ins with both Bishop’s Weed and Bugleweed. I purposely introduced them into my gardens and have battled with keeping them under control ever since.

Lots of plants in the mint family including oregano, are on my list of I thought, “Hey cool, let’s make Mojito’s or pizza sauce” to “OMG it took over my entire garden! I used to have other plants in here.”

Much of the county lands near the highway and walking trail near my home is covered with leafy spurge, which if it gets into your garden is very hard to remove. This three-foot-tall invader not only crowds out other species, but it spreads toxins that prevent native species from growing near it. Spurge seeds explode from capsules and can live in soil for seven years. Your neighbors will not appreciate it if you let this one invade!

Last year I wrote about Deadly Nightshade, which continues to be a problem. This summer I’ve found nightshade every time I weed. Again this is one you need to be vigilant about removing if you have children or pets that might taste.

Have you heard that Giant Hogweed has now been found in Wisconsin? This invasive grows six feet tall and produces toxic, blindness-inducing sap. The sap can result in severe burns to the affected areas of the skin resulting in severe blistering and painful dermatitis.

The Wisconsin Master Gardener program has great blog articles about invasives and weeds. Here’s an example of Purslane that I was researching recently, since it seems to sneak into my gardens each week while I’m at the office.

It’s hard to keep track of which plants are friend or foe, so that you can pull and eradicate. I’ve been trying out a couple phone apps with limited success. I did find this Wisconsin DNR list of invasive species and quick links to Invasive Plants Association of Wisconsin’s working list of invasives with PDF links that ID the plants. I’ve discovered and pulled at least a third if not half of the species on this list in my garden.


About Kary Beck

Mother and wife, gardener, wine enthusiast, avid online bargain hunter, and owner of two black-and-tan cocker spaniels.
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