After applying liquid weed and feed, it’s best to wait one to two days to water the lawn. However, you only have to wait 12 to 24 hours after applying most granular weed and feed products.
Weed and feeds are 2-in-1 lawn treatments that nourish the grass with nitrogen fertilizer while killing weeds with herbicide. After rigorous research, we reveal when to water after applying various types of weed and feed. Failure to follow our advice may lead to ineffective treatments or burnt grass.
Types of weed and feed products
To buy the best weed and feed, ensure it’s marked safe for your grass type. Then, consider its form and formula. Remember, if you don’t apply weed and feed properly, it can be bad for the lawn.
Liquid vs. granular form: When watering, form is foremost. Liquid weed and feeds are water-soluble, so they wash away if you water the lawn before they dry. In contrast, granular weeds and feeds are often activated with water.
Pre- vs. post-emergent herbicide: Products with pre-emergent herbicide prevent weeds from sprouting, and post-emergent herbicide kills visible weeds.
Organic vs. synthetic: Most weed and feeds contain synthetic chemicals. However, corn gluten meal is a lawn-safe organic fertilizer and weed killer. Synthetics work quicker but have a higher risk of fertilizer burn. Also, corn gluten meal improves soil quality, while chemicals degrade it.
Please read the directions on the product’s label, because each weed and feed is a little different. However, the table below highlights the typical watering instructions by weed and feed type.
| Type | How long to wait before watering |
| Liquid | 24 to 48 hours |
| Granular | 12 to 24 hours |
| Pre-emergent | 12 to 24 hours |
| Post-emergent | 48 hours |
| Corn gluten meal | 15 to 30 minutes |
When to water after granular weed and feed
You can water your lawn 12 to 24 hours after applying most granular weed and feeds. However, you may have to wait up to 2 days to water if the product contains post-emergent weedkiller.
| Pre-emergent | Post-emergent |
| Wait 12 to 24 hours to water | Wait 48 hours to water |
| Works beneath the soil’s surface | Often needs surface-level contact |
| Apply before you see weeds | Apply after weeds sprout |
Also, lightly water the lawn before applying granular weed and feed. “It is important to apply them when the lawn is wet, so that the dry pellets stick to the wet leaves, allowing uptake of the herbicide by the weeds,” explains Dave Minner, a turfgrass specialist at Iowa State University.
If it lightly rains before a granular application, you don’t have to water the lawn pre-application. However, if the lawn is soaked or flooded, it’s best to wait until the excess water evaporates. Refer to the table below for granular application tips.
| Application method | Apply with a fertilizer spreader. Follow the label’s recommendations. |
| Application area | Large areas, the entire lawn |
| When to apply | Typically in spring, but cool-season grass is sometimes treated in the fall. |
| When NOT to apply | During extreme heat or drought, Before or after heavy rain |
| How often to apply | 1 or 2 times per year |
When to water after liquid weed and feed
Liquid weed and feed is fast-acting and potent, so it should be used sparingly. Apply it to dry grass and wait until the product dries before watering the lawn. Typically, you can water 24 to 48 hours after a liquid application.
| Application method | Apply with a fertilizer sprayer or directly out of the package’s spray bottle. Follow the label’s directions. |
| Application area | Small areas, spot treatments |
| When to apply | Typically in spring, but cool-season grass may be treated in the fall |
| When NOT to apply | During extreme heat or drought, within 2 days of rain |
| How often to apply | 1 or 2 times per year |
FAQ about watering after weed and feed
It’s important to water after applying weed and feed to activate the herbicide, thoroughly distribute the product, and prevent fertilizer burn.
If you water too soon, it may wash away. Thus, you waste the product and pollute the groundwater.
If you wait too long to water after applying weed and feed, the product may not be effective.
Applying too much water after a weed and feed application can make the product less effective.
When to call a pro
Improperly applying weed and feed is ineffective at best. At worst, the potent chemicals can permanently damage your lawn and its soil. Hire a fertilization and weed control pro to save yourself from costly lawn repairs.
Lawn Love connects you to local pros. In addition to weeding and feeding your turf, they can help with routine lawn mowing and many other outdoor services. All our pros are vetted and insured, and it only takes a moment to get an online quote.
Sources:
“Spring Lawn Care.” By Dave Minner, extension turfgrass specialist. Iowa State University Extension and Outreach.
Main Photo Credit: rh2010 | Adobe Stock Free | License
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