How To Overseed My Fescue?

Q: I plowed and seeded my very shady front lawn with shade-tolerant fescue last fall. It came in kind of thin. I’d like to overseed but also need to lay down preemergent. What is the best way to do this? 

A: You can’t apply both seed and a preemergent in spring. I think you should overseed lightly now with 3 pounds of seed per 1,000 square feet. Fertilize now with any brand of lawn fertilizer that does not contain weed killer. Fertilize again in May at half-strength. In the future, cut your grass at your mower’s highest setting and water whenever the soil is dry. Carefully spot spray weeds. In your shady situation, I’d forgo area-wide weed killers altogether. Their effect on weak fescue roots is not worth the weed control you’d gain.