Timing the application of combined fertilizer and herbicide products, commonly known as “weed and feed,” is the most important factor determining its success on an Ohio lawn. This dual-purpose product includes nutrients to stimulate turf growth and chemicals to eliminate or prevent weeds. Applying it at the wrong time can be ineffective or damaging to the grass. Since Ohio’s climate fluctuates significantly, tailoring the application schedule to the life cycles of the turf and weeds is necessary for achieving a healthy, dense lawn.
Foundation for Timing in Ohio
Most Ohio lawns are composed of cool-season grasses, such as Kentucky Bluegrass and Fescue, which thrive during the cooler temperatures of spring and fall. These grasses enter a period of stress or semi-dormancy during the high heat of summer. This growth pattern dictates that the most effective and safest applications occur outside of the summer months.
The single most specific indicator for the first spring application is the soil temperature. Crabgrass, the primary target of spring pre-emergent herbicides, begins to germinate when the soil temperature consistently reaches 50 to 55 degrees Fahrenheit. Applying the pre-emergent herbicide before this threshold is reached establishes the protective barrier that prevents the weed seeds from sprouting.
The Spring Schedule for Weed and Feed
The spring application is a two-part process focused on weed prevention and initial feeding to recover from winter. The first step is applying a pre-emergent crabgrass control, timed precisely with the 50-55°F soil temperature window, typically mid-March to mid-April. This timing is necessary because the herbicide must be activated in the soil before crabgrass seeds begin to germinate. Once the seeds have sprouted, pre-emergent application is ineffective, requiring control with post-emergent products.
The second spring application should occur in late spring, about six to eight weeks after the first, generally in May or early June. This is the ideal time to apply a fertilizer with a post-emergent herbicide to target actively growing broadleaf weeds like dandelions. The fertilizer supports the cool-season grass as it enters its peak growth phase. This application must be completed before the summer heat sets in to avoid causing turf stress or burn. A second, lighter dose of pre-emergent can also be applied now to prolong crabgrass protection into early summer.
Summer Maintenance and Spot Treatment
During the summer months, particularly July and August, heavy “weed and feed” applications must be avoided on Ohio’s cool-season grasses. High heat and drought conditions push Kentucky Bluegrass and Fescue into semi-dormancy, and applying a nitrogen-heavy fertilizer during this period can burn the turf. If summer feeding is required, use a light application of a slow-release nitrogen formula. This provides sustained nutrient delivery without causing a sudden surge of growth.
The primary focus during summer shifts from blanket applications to targeted weed elimination. New or persistent weeds should be controlled with a spot treatment of a post-emergent herbicide instead of a full “weed and feed.” This approach minimizes the chemical load while addressing specific weed problems. Proper watering practices, such as deep, infrequent watering, encourage the root growth necessary for the lawn to withstand summer stress.
The Fall Application
Fall is the most important time to feed an Ohio lawn, as the cooler temperatures allow the grass to direct energy toward root development rather than blade growth. The first fall application should occur in early September to help the lawn recover from the stress of summer heat and drought. The fertilizer used at this time should be balanced to replenish nutrients and promote the quick recovery of the grass blades.
The final and most beneficial application, often called the “winterizer,” should be applied in late fall, typically between late October and mid-November. This application is designed to be absorbed by the plant and stored as carbohydrates in the root system. This acts as an energy reserve to promote earlier spring green-up and improve cold hardiness. This final feeding must be applied when the grass growth has slowed but before the ground freezes solid, ensuring the nutrients are taken up by the plant.
Fall is also an effective time for post-emergent weed control because perennial broadleaf weeds, such as clover and thistle, are actively moving nutrients down to their roots to prepare for winter dormancy. Applying a post-emergent herbicide during this period means the chemical is effectively transported to the root system, resulting in a more complete kill of the weed. This targeted approach in the fall sets the lawn up for a healthier, weed-free start the following spring.