Would a late summer fertilizer application harm a brown, dormant lawn?
Fertilizing a dormant lawn will not harm it. However, the turfgrass may not receive the full benefit of the fertilizer application. If the granular fertilizer remains on the soil surface because of a lack of rain, some of the material may actually volatilize into the air. It would be best to wait until growing conditions improve before fertilizing the lawn. Mid-September is an excellent time to fertilize Kentucky bluegrass lawns in Iowa. Lawns can also be fertilized in late October/early November.