Environmentally friendly compositions and methods of their use for promoting the growth of turfgrass over weeds

A method of applying a composition comprising boron and nitrogen to an area of lawn or turf, wherein said area comprises at least one perennial grass species and at least one weed species growing therein, wherein the applying occurs at least once during July to September, wherein the method results in an application rate of about 20 lbs/acre to about 100 lbs/acre of boron and about 25 lbs/acre to about 100 lbs/acre of nitrogen, and wherein the method promotes the germination, health, vigor and/or growth of the at least one perennial grass species and suppresses the germination, health, vigor and/or growth of the at least one weed species within one month following application.