Iron vs. Fertilizer on the Lawn

Yet another Dear Reader question!

"Should I use iron or fertilizer on the lawn?"

Er...when and where?

Fertilization of northern lawns should be done about four times yearly for best results.  Assuming you're using synthetics, late May, early September, early October, and whenever growth stops for the season.  That last one will vary year by year as it depends on the weather.  For very cold regions, the September and October feedings may move back a few weeks to compensate.  Regardless of the timing you choose, put down about 1 pound of nitrogen per thousand square feet per feeding, so around 4 pounds of nitrogen per year, for most northern lawns.

While organics can technically be thrown around any time you like, a good off the cuff schedule is mid May, early August (this one is optional), early September, and early October.  Then winterize when growth stops.

Southern lawns differ and I'm not an expert, but I do know that Bermuda grass is a heavy feeder during the hotter months and doesn't want to be fed when nearing dormancy.

Iron differs.  Technically, you can spread soil-applied iron any time you like.  Functionally, you'll find that growth in spring is so fast you can't get ahead of its iron requirements and color suffers regardless of what you do.  One drop of iron before a rainfall in mid June should hold you through the summer when growth is slower, however.  Then apply again in fall when growth slows a bit from the early-fall surge.

Spray iron can be applied any day the temperature will not go over 85° F.  If it suddenly does, wash it off the grass or it may burn.

In the case of spray iron, you're applying so little iron at one time that you can do it whenever color fades.  For bluegrass, that will be fairly fast.  For fescues, fairly slowly.