What is the name of the spray are you referring to? And what kind of weeds?
Ellen any kind of spray that will kill any weeds in liriope with out harming liriope
This page from University of Delaware Extension discusses this.
There are chemicals that can work, but most are expensive and likely only available to green industry professionals.
What are your most troublesome weeds? Are they grass-like or do they have broad leaves?
Here is our weed gallery with photos to help you with identification (or you can send us photos): https://extension.umd.edu/hgic/topics/weed-identification-photos
Some of both depending on time of year.
More grass like but IPM report last week named a couple of chemicals that I am not aware of and am searching if they really work with out harm.
There are some options that do work.
Please refer to this U. of Delaware publication: http://kentcoopextension.blogspot.com/2009/05/landscape-weed-control-in-liriope-beds.html
Some are pre-emergents which halts germination. Others are post-emergent which you are looking for.
Yes, there are herbicides that only act on monocots/grasses. You would have to read the labels carefully to see what plants it kills and what plants it can be applied over.
We generally do not recommend these herbicides to homeowners, and many are only available to people who are certified pesticide applicators credentialed by the Maryland Dept. of Agriculture.
Thank you Christine.
This is what I thought but wanted to verify that there is nothing new that I was not aware of.