Controlling your lawn weeds
You normally get two periods of weed activity in a normal year. The broadleaf weeds such as Cat's Ear, Plantains, Daisies, Dandelions to name a view of them will easily over winter in the turf. These need to be killed early on before the second turf weed season starts when you get the Red, White Clovers, Yellow Suckling Clovers and Trefoils appearing in around May and June time.
The selective turf herbicide is absorbed by the weeds and after a while, the weeds go into super growth, with their stems twisting and distorting. The weeds actually outgrow themselves and when their overall structure has literally had it, they die. Grasses do not have Cambium Cells so although they might absorb some of the chemical, it has no affect - if applied correctly in the first place!
Don't mow the lawn three days before or after the application of a lawn weed control product such as Weedol / Verdone or Vitax Lawn Clear. Available from The Lawn Shop as is a spray indicator dye called Indigo Garden Spray Dye to help you see where you have and have not treated.