How to water and mow for a healthy lawn
Water deeply in the early morning, mow fescue tall at 3.5 to 4 inches, and mulch your clippings.
Watering: deeply and infrequently. About one inch of water per week total, split into one to three long sessions, always in the early morning. Deep watering drives roots down; light evening watering invites disease.
Mowing height: for fescue, keep it tall, around 3.5 to 4 inches, especially in summer. Tall grass shades the soil, holds moisture, and crowds out weeds; scalping it short invites crabgrass and disease. Warm-season grasses (Bermuda, Zoysia) are cut lower. Keep your blade sharp; height and blade sharpness genuinely affect weed and disease pressure.
Clippings: leave them (mulch them). They return nitrogen to the soil. Bag only when the lawn is actively diseased or very overgrown.