said by Pacrat:"Half as much... Twice as often"
I think that is a friend of mines pickup line at the bars...
The wrong weed and feed on a lawn can be a big issue. So can over fertilizing. I usually spray weed-b-gone on the weeds twice in spring and 10-10-10 lightly over a lawn a few times a year starting in Feb/March, again in mid spring and then in October. Works for me..