Live in Northern VA...1/3rd acre Tall Fescue...cut to 3 1/2 inch length...20 degree slope...irrigation system...Southern exposure...full sun from dawn to dusk. Lawn is thick and almost weed free however, lawn can't seem to achieve dark green color. Applied granular Ironite about two weeks ago and have had a couple of good rain events since application. How long for Ironite to kick in? Any suggestions for yielding dark green turf? Thanks.