The bag at the hardware store says to apply in early spring. The homeowner spreads it across the Bermuda lawn in March. The grass is still dormant. The soil temperature is in the low 50s. The roots are not actively absorbing nutrients. And the fertilizer, which has nowhere to go, either washes into the storm drain with the next rain or sits on the surface feeding the winter weeds that are the only things growing.

That is what happens when lawn fertilization follows the calendar. When it follows the biology of the turf, the timing changes. The first application goes down when the soil temperature reaches the mid 60s and the warm season grass has broken dormancy and started active growth. The nutrients go into a root system that is ready to use them. And the response is visible within days rather than weeks.