If you are applying a weed and feed product that is meant to kill actively growing weeds, wait 2 days after application before watering. If the product you’re using is a weed and feed product with “crabgrass preventer,” it can be watered in 12–24 hours after application. The reason for this is that these two products work very differently. Weed and feed designed to kill established weeds must be absorbed through the leaves of the plants, so you should wait 48 hours before watering it. On the other hand, weed and feed designed to prevent weeds from sprouting must enter the soil to kill seedlings underground. So, you can water soon after spreading a crabgrass preventer weed and feed.
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What Kind of Weed & Feed Should You Use?
Weed and feed products come in two main types—those meant to kill existing weeds and those meant to prevent new weeds from sprouting. Before choosing, ask yourself the following questions:
- Are you trying to kill existing weeds (such as clover and dandelions) in your yard?
- Are you trying to stop annual weeds (such as crabgrass) from sprouting?
The answers to these questions determine what kind of weed and feed you should use. This is important because the different varieties of weed and feed should be watered at different times after you’ve spread them on your lawn.
Weed & Feed with Post-Emergent Herbicide
Weed and feed products with labeling that states they will kill weeds growing in your yard typically contain post-emergent herbicide. These products are designed to kill broadleaf weeds such as dandelion, clover, and purslane. They won’t kill or stop invasive grasses like crabgrass.
- Most weed and feed products are designed to kill established weeds in your yard—these products contain post-emergent herbicide.
- Post-emergent herbicide kills established broadleaf weeds (dandelion, clover, etc.)
- Weed and feed with post-emergent herbicide often show dandelions and clover on the packaging.
- Choose this weed and feed if you want to kill established weeds in your yard.
If your yard is currently overrun with established non-grassy weeds, a weed and feed product with post-emergent herbicide is the best bet. This herbicide is designed to infiltrate weeds through their leaves before killing them. It’s a great way to wipe out clusters of weeds while the fertilizer gives your grass a growth spurt.
Weed & Feed with Pre-Emergent Herbicide
If you’re using a weed and feed product advertised as a “crabgrass preventer,” then that product contains pre-emergent herbicide. Pre-emergent herbicide works by entering the soil, where it lingers for several weeks. During this time, any weed seeds that attempt to sprout are once they come in contact with the pre-emergent in the soil.
- Weed and feed products labeled as “crabgrass preventers” contain pre-emergent herbicide.
- Pre-emergent herbicide enters the soil and kills seeds as they sprout.
- Established weeds won’t be killed by pre-emergent—only new seedlings will be killed.
- Use this weed and feed with pre-emergent herbicide to stop weed invasions before they begin, while introducing a fertilizer at the same time.
Pre-emergent is best used to stop pest grasses like crabgrass and weeds from sprouting. It’s important to note that pre-emergent won’t kill established weeds. So, it’s important to apply your crabgrass preventer at the right time so you can kill weeds before they take hold in your yard.
Is There Weed & Feed with Both Pre- and Post-Emergent Herbicide?
Although you may be wondering if you can apply pre-emergent and post-emergent at the same time, the results are typically not good. Because these two types of herbicide don’t play well together, high-quality weed and feed products typically contain either pre-emergent or post-emergent herbicide—not both. This is helpful for you since pre-emergent and post-emergent herbicides have very different watering rules after application.
When Should You Water After Applying Weed & Feed with Post-Emergent Herbicide?
After spreading a weed and feed with post-emergent herbicide, wait 48 hours before watering. This time frame allows the herbicide in the weed and feed to infiltrate the weeds through their leaves. Once the herbicide has entered through the leaves, it will begin to kill the weeds. If you water too soon, you’ll wash the herbicide into the dirt. When post-emergent herbicide is washed off too soon, it will not kill weeds.
- Wait at least 48 hours after application before watering weed and feed with post-emergent.
- Post-emergent herbicide requires 48 hours to enter weeds through their leaves.
- If you water too soon, you’ll wash the herbicide off the weeds, rendering it useless.
If there is rain in the forecast, delay spreading your weed and feed with post-emergent herbicide. Although heavy rain is disastrous, even light rain can wash away the herbicide. Dry conditions are the best choice for these types of weed and feed.
When Should You Water After Applying Weed & Feed with Pre-Emergent Herbicide?
It’s best to wait 24 hours before watering a lawn where you’ve applied weed and feed with pre-emergent crabgrass preventer. However, weed and feed with pre-emergent herbicides are more forgiving than products with post-emergents. Pre-emergent herbicide needs to be watered into the ground in order to form a chemical barrier that kills seeds as they sprout. So, watering your lawn as few as 12 hours after application typically isn’t a problem.
- Wait 12–24 hours after applying a crabgrass preventer weed and feed before you water.
- Pre-emergent herbicides need to be watered in to work effectively, so a good watering or rainfall 24 hours after application is helpful.
- Do not overwater—this can wash your weed killer and turf builder out of the soil.
It’s important to note that both the fertilizer and pre-emergent herbicide in weed and feed are intended to linger in the soil for several weeks. During this time, the herbicide will kill weed seedlings underground while the fertilizer encourages green grass to grow. Excess water can wash both herbicide and fertilizer out of the soil, so it’s best to stick to a twice-weekly watering schedule for your lawn.
How Soon Can You Water After Applying Scotts Weed & Feed?
Wait 48 hours before watering after you apply Scotts Turf Builder Weed and Feed. This popular product contains two post-emergent herbicides—2,4-D and Mecoprop. Both of these herbicides need 48 hours to be absorbed by the leaves of the weeds. Then, it’s safe to water without disrupting their weed-killing action.
- After spreading Scotts Turf Builder Weed and Feed, wait 48 hours before watering.
- If you’ve spread Scotts Turf Builder with Halts Crabgrass Preventer, wait 12–24 hours before watering.
After using a broadcast spreader to apply Scotts Turf Builder with Halts Crabgrass Preventer, wait 12–24 hours before watering. Because this weed and feed contains the pre-emergent herbicide Pendimethalin, it’s safe to water your lawn the day after application. This will pull the weed control product into the soil, where it will kill sprouting weed seeds.
When Should You Water Your Lawn After Applying Weed & Feed?
Weed and feed products combine granular fertilizer with herbicide in order to promote green lawns and kill weeds. The best way to time begin watering after the time of application is:
- Wait 48 hours after applying a post-emergent weed and feed product before watering.
- After spreading a pre-emergent crabgrass preventer weed and feed, wait 12–24 hours before watering.
By waiting for this optimal length of time, your herbicide will work more effectively. This will not only wipe out more weeds, it will also encourage your grass to grow thicker and greener since there will be no weeds stealing the fertilizer in the weed and feed.