Periwinkle, also known as Vinca Minor, Creeping Myrtle, Running Myrtle, and Lesser Periwinkle, is a semi-evergreen ground cover plant that was once touted as a great ground cover. But now Periwinkle is listed on the Farm Services Agency USDA Invasive plant list and the invasive species-extension.org list.  I was one of those individuals who bought a 3-inch pot of periwinkle and planted it in my wooded backyard.  And yes, it grew very well and looked beautiful with green vegetation and purple flowers.  It contained the weeds, therefore, maintenance free.  What more could I ask for?  And then . . . I noticed it crowded out my lilies of the valley, hostas, and ferns.  I have since battled the plant trying to contain it within a small area. This article will introduce you to Periwinkle and discuss how to manage it.

Common periwinkle was first introduced to the U.S. from Europe in the 1700s as an ornamental. The green stems are slender but woody in appearance.  The green leaves are glossy and about an inch long.  Some of the varieties of periwinkle have variegated leaf color.  The flowers are generally purple to blue. The flowers resemble a phlox flower with 5 lobes and it blooms in May and June. It grows in sun, part-shade, and shady areas from dry to most soil. In other words, it adapts well to many surroundings especially shady areas. It is low growing at approximately 4-8 inches in height but its vine can be as long as 6.6 feet

But Periwinkle can take over wooded areas, forests, bluffs, and old homesites due to its dense matting. Because of this, Periwinkle is listed as invasive in other parts of the U.S., including Wisconsin - but not yet Minnesota. 

As a homeowner what can you do about the Periwinkle problem? There are several action steps you can take:

1. Don’t buy/acquire it 

2. If you have it on your property, try and contain or eradicate it.

3. Educate others.  Now that you know it is an invasive plant elsewhere, you can tell others about it.  

How do you get rid of it?  

There are several manual ways to get rid of periwinkle:

1. Hand pull it - but be sure to wear gloves!  You will need to pull it fairly close to the ground to make sure the vines/roots don’t break off,

2. Rake it. Raking the dense mats in large areas will get some of the vines and roots up.

3. Dig it up. Use a shovel or pitchfork and remove excess soil from the roots.  Be careful to get all the roots.

4. Mow it or string trim it. You can mow it and then dig it up. Mowing can help contain it. Avoid rotary tillers because any root left in the soil will just grow back.

5. Smother it with cardboard and mulch.  Cut, pull up, or rake up as much of the vinca first. Then add a layer of cardboard and 3 inches of mulch on top of the cardboard to smother the plant.  You may have to apply multiple times to fully eliminate.

If you must use an herbicide, be aware that the plant leaves are waxy, and therefore, herbicides may not work as effectively or may need a second application.  Trimming with a string trimmer, and then applying the herbicide may work better to reach the stems of the plant.    

Periwinkle can appear to be an attractive option if you are looking for a ground cover for tough areas. But, as this article shows, you may want to avoid this plant unless you are up for managing its massive spreading habit. 

Sources:

https://invasive-species.extension.org/vinca-minor-common-periwinkle/

https://www.minnesotawildflowers.info/flower/periwinkle

https://www.fsa.usda.gov/sites/default/files/documents/appendixe.pdf

https://ask2.extension.org/kb/faq.php?id=461054

Photo credits: www.uniprot.org (all creative commons) 1, www.forestryimages.org (all creative commons) 2