The Iowa Gardener: Invasive plants may be welcome in some gardens

With the help of Facebook, I’ve been doing a lot of sharing and swapping of plants with other gardeners in my area. It’s mainly been wonderful, but it’s also sparked a lot of online warnings and conversations about “invasive” plants?

What is an invasive plant? Some thoughts:

Just about any plant that a local gardener is sharing is something that grows vigorously in your area. Otherwise, they wouldn’t have excess to share with you.

If you are a beginning gardener, you may want to consider those plants that are exceptionally vigorous growers, known by some as “invasive” and others as “easy to grow.” Unlike more well-behaved plants, they will be difficult for you to kill. This can be, as they say, a feature and not a bug.

Some plants are clearly invasive, noxious weeds and should not be shared with others and not accepted, even if they’re free. These are plants that escape into the wild and edge out natives or diminish wildlife habitat.

Any decently tended Iowa yard isn’t likely to have a noxious weed problem, but Iowans who are doing prairie restorations, creating wildflower garden, or naturalizing areas of their properties should indeed make sure that they aren’t inadvertently cultivating noxious weeds, like thistle or multiflora rose. Check out a list of Iowa’s primary and secondary noxious weeds at seedlab.iastate.edu/iowa-primary-and-secondary-noxious-weed-list.

There are a number of other plants that are not on the official noxious weeds list that are still things to be concerned about: Pampas grass, orange “ditch lily” daylilies, purple loosestrife, yellow loosestrife, mint and others. If left untended, they will spread, grow thickly, and choke out less vigorous plants. They also can escape into your neighbor’s yard and create a headache for them. Not cool.

Invasive plants can vary by region. Maybe your cousin down in Texas has warned you to never grow water hyacinth because it can choke out waterways, but here in Iowa, the first frost kills these pretty water garden plants completely, so in central Iowa, you can grow them in contained water gardens with minimal risk.

One person’s invasive plant is another’s ideal garden plant. Case in point, wild violets (Viola odorata). They’re a native but can squeeze out other flowers and wreak havoc if you are trying to establish a lawn.

Other examples: A friend gave me some Turk’s cap lilies (Lilium superbum) several years ago. They behave themselves nicely in my garden as long as I regularly yank out the spreaders each year. Same with obedient plant (Physostegia virginiana). In the more moist areas of my garden, it’s invasive and I won’t grow it there. But on my dry front slope, it persists nicely where other plants have failed. If you have dry shade, Siberian squill (Scilla siberica) and bishop’s-weed (Aegopodium podagraria) will grow well where most others fail. But many a gardener, after a few years, has become frustrated with how these plants spread into every corner of their garden and end up yanking them all out.

Oxeye daisies (Leucanthemum vulgare) are often called “crazy daisies” because they reseed so prolifically all over your (and your neighbor’s) gardens. I’ve been growing them for 30 years now. Each summer I swear I’m going to yank out all of the endless seedlings and not let them grow in my garden any more. But each summer, I’m so charmed by their cheerful flowers I can’t bring myself to destroy them completely.

Other lovely plants that spread far too easily include sweet autumn clematis, heirloom types of morning glory, cleome, larkspur, Johnny-jump-up, and bachelor’s buttons.

That lily-of-the-valley that is driving your Uncle Bob crazy can be rescued by you, to put in the perfect contained spot between your garage and the sidewalk. And that creeping periwinkle you have that infests your perennial flower bed might end up the ideal ground cover for the north-facing slope of a neighbor down the street.

Just as a weed is simply a plant in the wrong place, an invasive plant can be simply a plant in the wrong garden.

Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at theiowagardener.com.