How Long After Using Weed Killer Can I Fertilize Lawn?

Updated February 21, 2017

To keep your lawn looking well-maintained, lush and green, you need to fertilise it and occasionally to use weed killer. Follow specific instructions on each of the packages or bottles containing the weed killer and fertiliser. Apply each solution on a sunny day when there is not a prediction of rainy weather for several days, because this helps the chemicals soak in, dry completely and do the work they are designed to do.

Natural Fertilizers and Weed Killers

If at all possible, use natural or organic weed killers and fertilisers to protect wildlife, pets and children from getting sick from eating, inhaling or licking chemicals designed to kill pests and encourage the growth of plants. Also, use a spray instead of using pellets or granules to cut down on the chance of an animal or human picking up the herbicide or fertiliser and ingesting it.

Close Application

You can apply weed killer and fertiliser within days of each other. Sometimes, you can apply them on the same day, depending on the needs of your lawn. For example, if you have only a few weeds in the yard, spray those specific plants and wait about 30 minutes. Then fertilise the yard, avoiding the plants and the area around the plants. You want the weed killer to have about two days to dry and to work before fertilising your yard. For irksome weeds, wait until they are dead before you fertilise.

When to Fertilize

Herbicides place stress on your lawn, so always apply them first. Then set up a regular schedule for fertilising your lawn. Always water your lawn before applying weed killer. Then fertilise about four times a year. A good schedule is to fertilise in April or May for the first period, in mid-June for the second period, in September for the third period and in November for the last period.

Safety Tips

When you are spraying or applying fertiliser -- or when a professional is applying it -- you will need to avoid getting close to any outdoor gates, cages or runs where your pets routinely spend time. The same goes for doghouses and pet playground areas. If fertiliser has not completely dried, curious furry ones can meddle in sprayed plants and become sick.

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About the Author

Vera Leigh has worked as a professional freelance writer since 2008. Her work has appeared in "Learn Overseas" and "Grad Source" magazines. In addition, she received an honorable mention in "Newsweek's" My Turn contest. She has written features for nonprofits focused on literacy, education, genomics and health. In her spare time, Leigh puts her English major to use by tutoring in grammar and composition.