When to Water the Lawn After Applying Weed and Feed 

Watering your lawn at the correct time interval after applying weed and feed ensures the product actually works. The type of weed and feed used determines the time frame in which the grass should be watered after administering the product. This article covers when to water the lawn after applying weed and feed, depending on the specific type. 

Keep reading to find out how to get it right the first time.

When to Water the Lawn After Applying Weed and Feed

When to water your lawn after applying weed and feed products is just as important as knowing how and when to apply weed and feed. Watering your grass too soon or too late can result in ineffective weed control and keep the fertilizer from creating a healthy lawn full of green grass. 

Find out below when to water the lawn after applying the different types of weed and feed products. 

Pre-Emergent Weed and Feed

A picture showing a person fertilizing lawn

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Pre-emergent weed and feed products require water to help them penetrate the ground to be effective. You can water the grass 12 to 24 hours after application. For the best results, wait at least 24 hours before watering.

Rain: The rain can help soak the herbicide into the soil. However, do not water the lawn if it rains after you apply weed and feed. Too much water can wash away the treatment. 

Post-Emergent Weed and Feed

Lawn fertilizer is spread by hand with a T-shaped tool that spreads fertilizer from both sides of an arrow-shaped element

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Homeowners should use post-emergent weed and feed products when it will be dry for a few days. These products are more sensitive to watering than their pre-emergent counterparts. 

Wait two days before watering the lawn to give the herbicide portion of the weed and feed time to absorb into the leaves of the weeds. If watered before 48 hours, the chemicals are washed away and will not work. 

Rain: Be sure to check the weather forecast and pick a time to apply weed and feed when it is going to be dry for a few days.

Granular Weed and Feed

fertilizer for the lawn

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For granular fertilizer to work, it must be watered into the ground to release the lawn food that makes grass healthy and gives you a green lawn. If the fertilizer does not receive water, it can burn the grass if it sits on the lawn during the summer.

Wait 12 to 24 hours before watering your lawn after applying granular pre-emergent weed and feed.

Grass treated with granular post-emergents should not be watered for at least 48 hours.

Liquid Weed and Feed

Unlike granular products, liquid weed and feed does not require watering to work. And you do not have to wait as long to water the lawn. As a rule of thumb, waiting at least 24 hours is best. Too much watering can render the chemicals ineffective, so be mindful of this when you turn on the sprinklers.

Pre-Emergent and Post-Emergent Weed and Feed

The chemicals in these two different types of weed and feed do not mix well. Therefore, homeowners are advised not to use both a pre-emergent and post-emergent at the same time. Here are some reasons why:

— They should be watered at different times after application.
— They should be applied at different times to work. Pre-emergents should be used in early spring. Post-emergents should be applied in the late spring.

What is Weed and Feed?

Weed and feed is a combination of chemicals to treat weeds and fertilize the grass. The lawn fertilizer – the “feed” part – contains nitrogen, phosphorous, and potassium, important plant nutrients. The weed control portion can be either a pre-emergent or post-emergent herbicide. 

Pre-Emergent Weed and Feed: Pre-emergent weed and feed products have herbicides to stop weed seeds from germinating. Pre-emergent products do not kill weeds. Depending on the ingredients, pre-emergent weed and feed inhibits cell division, prevents root growth, or stops enzyme growth to keep weeds from growing in the first place. 

Post-Emergent Weed and Feed: Post-emergent two-in-one products have chemicals that kill weeds that are already growing. Contact-based products kill the plant parts they come into contact with, which is typically the parts above ground. Systemic post-emergents can be sprayed on any part of the weed and are absorbed into the plant, destroying its entire vascular system. 

What Weed and Feed Should You Choose?

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Pre-Emergent vs. Post-Emergent: If you want to prevent weeds from growing, you’ll want a pre-emergent weed and feed. A post-emergent weed and feed is best in yards already held hostage by weeds. 

Liquid vs. Granular: If you want to spot-treat weeds, liquid weed and feed products allow you to target individual weeds. Granular weed and feeds use a spreader to apply to a larger area. If you have a lot of weeds throughout your yard and want to apply chemicals quickly, a granular product may be best.

Grass Type: The type of grass is also a part of the decision of which weed and feed to select. Weed and feed labels list which types of grass they can be used on and at what stage. For example, pre-emergents should never be used on turfgrass recently seeded. 

Some chemicals can be used on warm-season grasses but not on cool-season grasses and vice versa. Scotts Turf Builder is an example of a weed and feed that can be used on both. 

Why Weed and Feed May Be Bad for Your Lawn

Weed and feed products are conveniently available and can be found at many home improvement brick-and-mortar locations and online stores like Amazon. However, weed and feed can be bad for your lawn for the following reasons:

— The best time to fertilize your lawn and the best time to treat weeds are often different. 
— The chemicals in weed and feed are dangerous for children and pets.
— Weed products are often only needed in specific areas, while fertilizer is required all across the lawn. 
— The harsh chemicals in weed and feed can leach into the surrounding environment. 
— Weed and feed can sometimes harm plants other than weeds, including grass, shrubs, and trees. 

FAQ About Watering After Weed and Feed

How long should you wait before mowing the grass after using weed and feed?

Give the product time to work. Wait at least three days before you mow the grass

When can you aerate your lawn after applying weed and feed?

You should wait four weeks after applying weed and feed before aerating your lawn.

Are liquid and granular weed and feed applied differently?

Yes. Liquid weed and feed products are applied using a sprayer. Granular weed and feed chemicals are disbursed using a drop-type spreader, rotary spreader, or broadcast spreader.

Should you water your grass before applying weed and feed?

Watering the lawn before applying granular products is helpful. It can help the granules stick to the weeds. Be sure to follow the product’s instructions.

When is it safe for children and pets to come back on the lawn?

Wait until after a heavy rainfall before allowing your loved ones back on the grass. You can also water your lawn for a few days in a row to be sure the residual from the chemicals is washed away.

How soon can a lawn be reseeded after applying pre-emergent herbicide?

Homeowners should wait at least 8-10 weeks after applying weed control to reseed a lawn, or the herbicide could kill the grass seeds.

Final Thoughts 

Getting the timing right on when to water your grass after applying weed and feed will determine if the chemicals work. It will also affect whether you end up with an attractive, healthy lawn.

Keeping up with when to water the grass takes time and effort. You could end up spending more time and money correcting your mistake if you do not get it right. 

If you prefer to let someone else handle your lawn care chores and eliminate the risk of you messing up the timing, WikiLawn can connect you with lawn care professionals in your area who can help control weeds and maintain your grass for an appealing, healthy lawn.

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About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!