Master Gardener

Bev Johnson

Warning, this is a re-run but still relevant.

Bunkey was thrilled to death when his neighbor down the street brought him a pretty red yarrow. Now two years later, he has had to resort to Roundup in an attempt to get rid of it. Yarrow is one of our plant thugs and, except for the native white one, not even a good pollinator. Most hybrid plants aren’t.

There are quite a few plants that can become invasive if given a chance. A good description of an invasive plant is one that is a neat clump the first year after planting. Two years later it smothered all of its neighboring plants and part of the next- door neighbor’s yard and is heading for the nearest Interstate highway.

Here are a few flowers you should never put in your flower gardens.

Old fashioned day lilies and old-fashioned tiger lilies. The Tigers reproduce like rabbits and can carry a disease that can affect your hybrid lilies. The daylilies are ugly and the clumps hard to get rid of.  Any ditch plants. Sure, they look great as you drive by, but they are contained by other weeds and usually poor soil. Put them in nice fertile soil and they go nuts. Common tansy and even the colored ones are nearly impossible to kill off. Aumur silver grass, miscanthus saccharflourus, is a thug. The last part of its Latin name means sweet. A misnomer if there ever was one.

To see invasiveness in bloom locally, check out the pretty yellow “ground cover” in the ditches, near Walmart and scattered all over the city of Fergus Falls. This is bird foot trefoil. It forms such dense mats that it chokes out any other plant. The Minnesota Highway department planted it and crown vetch, a pretty purple invasive plant on steep slopes to hold them, a very pretty combination but deadly in your yard. Purple coneflower spreads by seed and root. A small bell flower that looks just like a foot high purple chicken drumstick and a taller cousin with single blue bells, often found around foundations are both monsters. They thrive on Roundup.  Lily of the valley and Canada white violets are great ground covers in shaded areas but can be difficult to keep under control.                                      

One water plant you should never plant is flowering rush. This one can out compete cattails. And you know how well they can spread. It will even crowd out willows. Purple loosestrife or even hybrid loosestrife as it can escape and strangle our native water plants.

Trees and bushes can be criminals too. The University of Minnesota puts Aumur and Norway maples on the thug list as they can crowd out our native trees. Japanese barberry, Siberian pea shrub, and Russian olive trees are on the University of Minnesota’s restricted noxious weed list. 

The exotic honeysuckles, Lonicera taratarica and L. Morowii, Buckthorn, and Siberian elm are all non-natives. Don’t plant them.  Replace them with a native shrub or tree.

  Canada Red cherry and its native cousin the choke cherry spread by shoots. Since these two have fruit for the birds, just mow around them to reduce the sprouts.

Beware of a person with a wheelbarrow full of plants offering you one. They are bound to be thugs. Otherwise, there would not be so many of them to share.  Most of them aren’t even good ground cover or very pretty.