Knowledgebase
pre-emergent application #926053
Asked March 15, 2026, 9:35 AM EDT
Arapahoe County Colorado
Expert Response
Hello,
Thanks for reaching out to Ask Extension with your question about dandelions.
If you are wanting to use a pre emergent on your dandelions, then you should do it soon, before any seeds start to germinate. Dandelion seed germination can occur when soil temps reach anywhere from 50 to 75 degrees, and can germinate all season long in the right conditions.
A pre emergent will only keep new seeds from germinating, and won't kill any existing dandelions that overwintered (they are perennial).
Here is more information about dandelions and controlling them:
https://ipm.ucanr.edu/home-and-landscape/dandelion/#gsc.tab=0
As with any chemical, always follow the label, as the label is the law. Your pre-emergent product will let you know how much to use, when to use it, how to apply it, and how often it can be reapplied.
I hope this helps,
Dawn
