Annual weeds that produce seeds and grow back each year require weed and feed applications to prevent continued growth. Chemical treatments for Ohio lawns begin in March, when the soil is just beginning to warm.
Apply a pre-emergent weed and feed in early spring to control the growth of crabgrass and germinating weeds. The best time to apply a pre-emergent is March in the southern half of Ohio and April for the northern half. These weeds begin to grow and spread once the soil temperature reaches 52 degrees Fahrenheit.
Apply a post-emergent weed and feed as soon as the crabgrass or other germinating weed appears in the lawn. The best time to apply this type of weed and feed in Ohio is late May for the southern half of the state and mid-June in the northern half. Two applications of the post-emergent set two weeks apart will assist with control.
A lawn growing on a nutrient-rich soil will have lush growth that limits the ability of weeds to find room to grow. Applying a spring and fall grass fertilizer will return lost nutrients to the soil. Choose to spot treat areas with a weed and feed fertilizer if they require additional help from herbicide.