The weeds are still actively growing then, but they re also storing up food for winter. In most years, good control is possible any time from September through early November. Usually a flush of new dandelions germinates about mid-October. They re most likely to invade thin lawns. Combinations of fertilizer and broadleaf weed herbicide can be effective applied to tall fescue and Kentucky bluegrass lawns in September or November.
Soil moisture is plentiful.
The dandelions won t be receiving any water for at least 24 hours after the application, whether through rain or irrigation. If in a lawn, the weeds won t be facing a mower for several days both before and after spraying. Temperatures are above 50 F, yet below 80 F. Wind speeds are below 5 mph. The person applying the herbicide follows its label directions exactly. For example, your type of turfgrass can affect which dandelion control you can use without harming the lawn.