We all look forward to the birth of spring, when our gardens are full of growth, and we’re able to spend more time outdoors. At times, our excitement to begin gardening can turn to confusion when we realize we’re not sure what’s growing. “Is this a weed?” is one of the most common questions I get asked. I tend to put weeds into a couple of categories: Non-native invasives and Invasive natives. The first category I almost always recommend getting rid of, because they are responsible for ruining the biodiversity of our forests and prairies, and limiting plant and animal life.
Here are a couple of species that we see a lot of in Dane County, and they are quite pretty! It can be hard to pull something that you enjoy, but it’s important that we keep them under control, so that they don’t out-compete our native plants and the plants you’re growing in your garden.
Campanula rapunculoides, known as Creeping Bellflower, is highly invasive. The stalks of light purple flowers can be seen all over Madison in midsummer. It can often be confused for Adenophora lilifolia, and has been sold in plant nurseries that way. Though also not native, Adenophora does not have the same invasive qualities. One of the difficulties about Creeping Bellflower is that it reproduces via rhizomes and seed. Here is what the Wisconsin DNR recommends for control:
Mechanical: Dig at least 6” deep and several inches out from the plant to ensure you have gotten all of the roots. Repeated pulling or mowing in a growing season will weaken the plant but will not kill it.
Chemical: Apply a glyphosate solution using foliar spray or
wicking method. If not wanting to damage grass, herbicides with dicamba as the active ingredient can be applied.
Hesperis matronalis, known as Dame’s Rocket. It is often mistaken for Wild Phlox (Phlox divaricata) because they bloom at the same time. One way to differentiate them is Dame’s Rocket has 4 petals, and toothed margins on the leaves. Wild Phlox has 5 petaled flowers, and smooth leaves. Unfortunately, Dame’s Rocket has been included in some wildflower seed mixes. Avoid those mixes!
Mechanical: Pull plants in early spring; plants in bloom should be bagged and disposed of in a landfill. Burn infested areas in seedling or rosette stage.
Chemical: Foliar spray with glyphosate or triclopyr on large infestations in late fall when native plants are dormant but the basal rosettes of dame’s rocket are still green.
As with all weeds, the most important quality is diligence! After a spring cleanup, the best way to keep weeds down is to walk through and enjoy your garden daily (or at least weekly!) and pull up what doesn’t belong. Happy Gardening!