vinca minor eradication
I have been working to eradicate vinca minor from a hillside along my long driveway. I'm now going into the third year working on this project. Some areas have been successfully removed by digging out down to the roots and replanting with a ground cover. The soil was loose so it came out fairly easily. But the rest is growing into more clay-like soil and isn't being removed as easily. So I have had to resort to using glyphosate on the rest. After mowing it close to the ground, I sprayed it and waited several weeks to see if it was dead. It was brown and dried up so looked quite dead. I began digging it out again only to discover that some plants had just the slightest tiny green leaves starting to grow back near the base of the plants. I dug these remaining plants out hoping to get any and all parts that could be viable. It is now early September and I don't want to replant anything on the rest of the hillside until I'm absolutely sure that the vinca won't come back, so I'm thinking I will wait til spring. But I don't want to leave the soil bare throughout fall and winter. What can I do to stabilize the soil, keep new weeds from germinating, and hopefully also keep the vinca from coming back? Should the hillside be covered with cardboard and mulch on top? Would that smother any new vinca emerging? Should I solarize with clear plastic all winter? I want this vinca never to come back!!
Baltimore County Maryland
The cardboard (or 3-5 layers of newspaper) overlapping topped with mulch is a good idea. Cardboard lasts longer than newspaper. If the grade is steep, the mulch may be washed off the cardboard more easily than the newspaper in a heavy rain. You may want to lay some branches sideways here and there on the hill to slow rain and stabilize the mulch.
We would not recommend trying to solarize (not hot enough here.)
The main problem will be tiny pieces of root that may manage to put out a new plant in a year or so. That's almost impossible to stop at this time. Just keep an eye out for them and pull ASAP. Vinca can also start from seed, so it is possible that could happen, though not commonly a problem. Again, just keep an eye out.