Can Weed & Feed Be Used Over Lawn Fertilizer?

Weed and Feed First Application

• Weed and feed must be applied after annual weeds germinate and grow in order for the product to work. Annual weeds such as dandelions start germinating when soil temperatures are over 77 degrees Fahrenheit in the spring. At this point, the lawn is just coming out of dormancy and has not been fertilized. You can judge when to apply weed and feed by examining the yard for young broadleaf weeds. Killing weeds when they are young with weed and feed is more effective than trying to kill them when they have matured.

Weed and Feed's Second Application

• The second application of weed and feed comes in the fall to remove your cool-season weed population. Applying weed and feed during the summer increases your chances of burning the lawn with chemicals while temperatures are hot. Your second weed and feed application will be used over the remnants of your summer fertilizer applications. However, you should apply weed and feed just as your did in the spring. Be sure to use the proper amount to prevent yard damage.

Regular Fertilizer Application

• Lawns are generally fertilized every six to eight weeks. Therefore, you can plan on fertilizing again after applying weed and feed in roughly two months. Use 1 pound of nitrogen per 1,000 square feet when you fertilize during the summer. Gardeners who use more than that cause fungal diseases from encouraging a flush of new growth, which stresses root systems. Time your summer fertilizing schedule, so that you have time for a second application of weed and feed in the fall.

Other Factors

• Weed and feed cannot be used on all lawns. For example, centipede, Bermuda and zoysia lawns should not be given weed and feed products, according to gardening writer Walter Reeves. These grass types must be fertilized after they green up for the season. By the time these grasses green up, annual weeds may have already matured and be more difficult to kill. Also, choose a dry period of 48 hours to apply weed and feed. The herbicide needs time to absorb into the foliage of weeds.