How can I get rid of a large patch of native violets so that I can plant new perennials?
Allegheny County Pennsylvania
Hello, and thank you for uing the ask an expert system. Controlling wild violets can be difficult becase they grow from tiny rhizomes that overwinter in the soil. You can manually dig them out, but you must be sure to get all the little rhizomes. You may want to combine diging with chemical treatment. Since there is nothing but violets in the area you want to clear, a nonselective herbicide like glyphosate, the active ingredient in Roundup and other herbicide products can be applied. Glyphosate works best on actively growing plants so you will need to wait until the violets are up and growing this spring. The best control will occur in the fall, but I assume you want to be able to plant the bed this growing season. Glyphosate is fairly short lived so you should be able to plant your perennials two to three weeks after the last application of chemical.
If you dig out the majority of rhizomes you will have fewer live plants to eradicate. Glyphosate is a non-selective herbicide so you need to be carefull to avoid spraying other plants in the area. Choose a calm day with no rain expected for 24-48 hours.
Read the label carefully and follow all directions. I am attaching a link to a publication on controlling violets to this answer. I hope this helps.