- How do post-emergent herbicides work?<\/a><\/li>
- Before you start<\/a><\/li>
- The application process<\/a>
- Liquid post-emergent<\/a><\/li>
- Granular post-emergent<\/a><\/li><\/ul><\/li>
- Post-application steps<\/a><\/li>
- FAQ about how to apply post-emergent herbicides<\/a><\/li><\/ul> \t\t\t<\/div> \t\t<\/div><\/div>
How do post-emergent herbicides work?<\/span><\/h2>
![\"weeds](\"https:\/\/lawnlove.com\/blog\/wp-content\/uploads\/2025\/02\/AdobeStock_275997423-1.jpeg\")
Zigmunds<\/a> | Adobe Stock Free | License<\/a><\/figcaption><\/figure> Post-emergent herbicides<\/a> target established weeds that are difficult to remove manually or with organic weed killers<\/a>. The product you choose and how and when you apply it should align with the types of weeds you have.<\/p>
Depending on the level of infestation in your yard, choose between blanket or spot treatments.<\/p>
Blanket treatments <\/strong>can <\/strong>help if your entire lawn is overrun with weeds. Use a liquid or granular selective post-emergent to only target the weeds<\/em>. Using a non-selective will kill your grass and other desirable plants along with the weeds.<\/p>
Spot treatments<\/strong> address minor weed issues, such as small weed clusters. They work well around:<\/p>
- Flower beds<\/li>
- Ornamental gardens<\/li>
- Sidewalks and driveways<\/li>
- Trees and shrubs<\/li>
- Lawn edges
<\/li> - Use a liquid selective herbicide that only targets the weeds and makes it easy to apply to specific lawn areas. <\/li> <\/ul>
My tip<\/strong>: Always treat the weeds when they\u2019re actively growing. This is when they\u2019re most vulnerable to post-emergent treatments.<\/em><\/p>
Additional relevant articles:
<\/p>- 7 Best Post-Emergent Herbicides of 2024<\/a><\/li> <\/ul>
Before you start<\/span><\/h2>
Check the weather<\/span><\/h3>
Check the weather forecast and choose a calm, dry day for application (but no drought). Avoid rain for at least 24 to 48 hours after application to allow herbicide absorption. <\/p>
Gather your equipment<\/span><\/h3>
To successfully apply post-emergent herbicides, you\u2019ll need the right tools and materials:<\/p>
- First, identify the weeds in your yard and purchase a herbicide that targets them<\/a>. <\/li>
- Then, gather protective gear (gloves, long-sleeved clothing to minimize skin exposure, eye protection, mask), marker flags, hose or sprinkler system<\/a>, and cleanup supplies (soap, water, and possibly a change of clothes) <\/li>
- Next, get what you need if you\u2019re applying a liquid post-emergent<\/strong>:
- Backpack sprayer<\/a> (easy to maneuver and allows for precise application), boom sprayer (can be attached to an ATV or lawn tractor for efficiency and covers wide areas faster), Hand-held sprayer<\/a>, or hose-end sprayer <\/li>
- Sprayer nozzle to control the spray pattern and droplet size<\/li>
- Measuring cup or syringe (helps measure small, exact amounts of herbicide for spot treatments)<\/li>
- Bucket for mixing the herbicide with water<\/li>
- Spray shield or drift guard<\/a><\/li> <\/ul> <\/li>
- Alternatively, you\u2019ll need the following for granular post-emergent<\/strong>:
- A broadcast spreader<\/a> (for large areas) or drop spreader (for smaller areas)<\/li>
- A broom and dustpan to pick up leftover granules from your driveway or walkway<\/li> <\/ul> <\/li> <\/ul>
Prepare your lawn<\/span><\/h3>
![\"cutting](\"https:\/\/lawnlove.com\/blog\/wp-content\/uploads\/2024\/07\/AdobeStock_290201183.jpeg\")
rh2010<\/a> | Adobe Stock Free | License<\/a> <\/figcaption><\/figure> - Mow your lawn as usual, according to your grass type. This allows the herbicide to make better contact with the weeds. Wait a day or two after mowing to apply the treatment; freshly cut grass is more sensitive to chemicals.<\/li>
- Clear the lawn of leaves, sticks, branches, and general debris to allow easy herbicide access to the soil. Debris can also cause uneven application.<\/li>
- Take note of delicate plants, garden features, and sprinkler heads in your yard that could be affected by the application. You\u2019ll want to avoid damage to them.<\/li>
- Place marker flags around the yard. First, define the perimeter of the area you want to treat. Then, divide it into rows to make the application easier.<\/li>
- Look at the bag or bottle to see if you need to water your lawn before application. Typically, the soil should be slightly moist to absorb the post-emergent (granular or liquid) perfectly. Weeds are also more \u201copen\u201d to the herbicide when the soil is moist.<\/li> <\/ul>
The application process<\/span><\/h2>
Liquid post-emergent<\/span><\/h3>
![\"Spraying](\"https:\/\/lawnlove.com\/blog\/wp-content\/uploads\/2024\/09\/AdobeStock_271489615-1.jpeg\")
dean<\/a> | Adobe Stock Free | License<\/a><\/figcaption><\/figure> First, mix the herbicide with the amount of water written on the label. You can use the bucket or mix the liquids directly in the sprayer. Shake or stir well before using. <\/p>
Second, spray clean water over a particular area to check the output. If it\u2019s not right, adjust the nozzle to match the recommended setting.<\/p>
Then, start treatment:<\/p>
Liquid blanket treatments<\/span><\/h4>
- Begin at the outer edge of your lawn and work your way in, spraying the product in straight rows according to the marker flags. Walk at a steady pace. <\/li>
- For an even application, keep the sprayer around 2 feet off the ground at all times and slightly overlap each pass.<\/li> <\/ul>
Liquid spot treatments<\/span><\/h4>
- Aim the sprayer directly at the weeds you want to eliminate. Spray them until the leaves are saturated, but avoid excessive runoff<\/a>. <\/li>
- Work systematically through the marked areas.<\/li> <\/ul>
Granular post-emergent<\/span><\/h3>
![\"bags](\"https:\/\/lawnlove.com\/blog\/wp-content\/uploads\/2024\/08\/granular-herbicide-1.jpeg\")
JJ Gouin<\/a> | Adobe Stock | License<\/a><\/figcaption><\/figure> Using the label instructions, calibrate your spreader before application. This helps you apply the correct amount of product to your lawn and avoid burning the grass. It also ensures the treatment is effective. After that, pour the granules into the spreader on a flat, hard surface to prevent spills.<\/p>
Then, start treatment:<\/p>
- Apply the herbicide around the perimeter of the treatment area, then move to the center in parallel passes. Walk at a consistent speed to distribute the granules evenly. Slightly overlap your passes to prevent missed spots, but avoid over-application.<\/li>
- Take breaks to see if the spreader is applying the granules evenly. <\/li> <\/ul>
Special considerations<\/p>
To get the best results from your post-emergent, take a few extra steps to protect nearby plants and the environment.<\/p>
Cover the entire weed leaf<\/span><\/h4>
For the herbicide to be fully effective, cover the weed leaves entirely. This allows the active ingredient to be fully absorbed. Missing parts of the leaf can cause some weeds to survive. <\/p>
If you\u2019re using a liquid herbicide, use a fine spray to saturate the weeds. Likewise, spread granules evenly across the target area.<\/p>
Use barriers to protect sensitive plants<\/span><\/h4>
Herbicides can damage plants you want to keep if they touch the leaves or roots. <\/p>
Before spraying your liquid post-emergent, set up barriers like cardboard, plastic, or plant covers. For granules, don\u2019t apply them too close to the plants and water them in to stop drift.<\/p>
Stop if the wind picks up<\/span><\/h4>
Wind can cause herbicide drift, damaging plants, polluting water, or irritating your skin and eyes. <\/p>
If it picks up mid-application, stop and wait for calmer conditions to continue.<\/p>
Don\u2019t overapply your herbicide<\/span><\/h4>
Stick to the recommended dosage on the herbicide label; using more than necessary doesn\u2019t improve weed control and may stress your plants, contaminate the soil, and harm the environment. <\/p>
Post-application steps<\/span><\/h2>
You’re almost done \u2013 with a few important steps left to follow:<\/p>
Keep off the treated area<\/span><\/h3>
Keep your little ones and pets off the treated lawn until it’s safe. Since they often play, sit, or roll on the grass, they\u2019re more likely to come into contact with chemicals. Waiting gives the herbicide time to dry and absorb, lowering the risk of exposure.<\/p>
Water the treated area<\/span><\/h3>
- For liquids<\/strong>: Only water if the packaging says so and within the timeframe indicated (usually a few hours). Not all liquid products require watering. <\/li>
- For granules<\/strong>: Watering activates them and helps them stick. Don\u2019t overwater, or it will wash them away.<\/li> <\/ul>
Clean your equipment<\/span><\/h3>
Use soap and water to thoroughly clean the tools you used to apply your post-emergent herbicide. <\/p>
Pro tip for sprayers<\/strong>: Weed and horticultural experts at Utah State University advise against using the same tool for herbicides and pesticides. \u201cSome herbicides such as 2,4-D are difficult to completely remove from sprayers. Damage to desirable plants could result from a herbicide-contaminated sprayer used to apply insecticides.\u201d<\/p>
Store the herbicide<\/span><\/h3>
Store herbicides safely where your kids and pets can\u2019t reach them, like in a locked cabinet or up high. Even tiny amounts can pose a risk if eaten or touched, so keep the lid on tight.<\/p>
Also, store your herbicides in a cool, dry spot with some airflow. Moisture, direct sun, and extreme temperatures can make the active ingredients less effective. A shed, garage, or basement with stable temperatures is ideal.<\/p>
Before storing, check the container or package for leaks or cracks. If it\u2019s compromised, move the product to another labeled container or dispose of it as directed by local regulations.<\/p>
Monitor results<\/span><\/h3>
Check the treated areas closely. If the herbicide is working, the weeds will start wilting, stop growing, and look discolored, indicating that the herbicide is working.<\/p>
Other weeds might persist, in which case you should re-apply the herbicide according to the wait time on the label. <\/p>
Maintain your lawn properly<\/span><\/h3>
![\"illustration](\"https:\/\/lawnlove.com\/blog\/wp-content\/uploads\/2021\/10\/rsz_aeration.png\")
Infographic by Juan Rodriguez <\/figcaption><\/figure> A well-maintained, thick, healthy lawn can naturally crowd out weeds, reducing the need for herbicides. Here\u2019s what to do:<\/p>
- Mow at the right height<\/a>. Cutting your grass too short weakens it, making it more vulnerable to weeds, drought, and disease. Set your mower height based on your grass type. <\/li>
- Fertilize correctly<\/a>. Choose your fertilizer based on the results of a soil test<\/a>. Giving your lawn the right nutrients at the right time helps it grow thick and strong. <\/li>
- Water properly<\/a>. Water your lawn well but less frequently to promote deep root growth. Try for 1 to 1.5 inches of water per week, whether from rain or irrigation. Water in the morning to reduce evaporation and fungal problems. <\/li>
- Aerate the soil<\/a>. If your soil is compacted<\/a>, it prevents air, water, and nutrients from reaching the roots. This causes weak grass and weeds. If you have warm-season grass<\/a>, aerate in late spring to early summer. For cool-season grass<\/a>, try early to mid-fall. Core aeration<\/a> can also improve soil structure.<\/li>
- Overseed to fill in bare patches and prevent future weeds. Match new grass seeds to your existing lawn for the best results.<\/li> <\/ul>
FAQ about how to apply post-emergent herbicides<\/span><\/h2>
Can I apply post-emergent herbicide in hot weather?<\/strong>No, avoid applying in temperatures above 85 degrees Fahrenheit as the herbicide may evaporate or damage desirable plants.<\/p> <\/div>
How long does it take post-emergent herbicide to work?<\/strong>You\u2019ll typically see results within seven to 14 days, but it can vary depending on the weed type and environmental conditions.<\/p> <\/div>
What if I accidentally spray herbicide on desirable plants?<\/strong>Rinse the plants immediately with plenty of water to dilute and remove the herbicide.<\/p> <\/div>
Do \u2018weed and feed\u2019 products work?<\/strong>The University of Florida IFAS Extension says weed and feed should only be used when weeds cover the entire lawn evenly, which is rarely true. Some homeowners also use the herbicide component as a pre-emergent<\/a>.
Keep weeds out of your yard<\/span><\/h2>
Managing weeds on your own is simple, but not everyone is ready for the task. If you’re in that boat, a local weed removal specialist<\/a> can take over and make sure your yard meets your expectations.<\/p>
Plus, Lawn Love can connect you with a local lawn care expert<\/a> who can maintain your lawn so you can prevent future weed infestations.<\/p>
\t\t\t\t\t\tSources<\/strong><\/p> \t\t\t
<\/span><\/div> \t\t<\/div> \t\t\t- Utah State University Cooperative Extension<\/a><\/li>
- University of Florida IFAS Extension<\/a><\/li> <\/ul> <\/div> \t\t<\/div> <\/div>
Lawn Love participates in the Amazon Services LLC Associates Program, an affiliate advertising program. LawnStarter earns revenue from products promoted in this article.<\/em><\/p>
Main Photo Credit: Tomasz Zajda<\/a> | Adobe Stock Free | License<\/a><\/p>","protected":false},"excerpt":{"rendered":"
To apply post-emergent herbicides, gather your materials, use the herbicide as directed on the bag, and follow some post-application steps.<\/p>\n","protected":false},"author":98,"featured_media":36483,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_et_pb_use_builder":"off","_et_pb_old_content":"\n
Weeds are a pain in the grass, and post-emergent herbicides are your pain relief. We\u2019ll show you when and how to apply post-emergent herbicides to get rid of dandelions, crabgrass, and other common invaders of lush, green lawns. <\/p>\n\n\n\n
How post-emergent herbicides work\u00a0<\/h2>\n\n\n\n
Post-emergent herbicides are part two of a one-two weed knockout punch. Apply pre-emergent herbicides<\/a> to nip weeds in the seed underground and then spray or spread post-emergent herbicides when weeds spring up in your yard.<\/p>\n\n\n\n
There are four types of post-emergent herbicides, and each works in different ways.<\/p>\n\n\n\n
- Systemic post-emergent herbicides<\/strong> are absorbed directly into the plant to kill from the root up. <\/li>
- Contact post-emergent herbicides<\/strong> leave a coating on the plant to prevent photosynthesis. <\/li>
- Selective post-emergent herbicides<\/strong> target specific weeds and won\u2019t destroy nearby grass or plants.<\/li>
- Non-selective post-emergent herbicides<\/strong> destroy everything in the area of application and should be used with discretion. <\/li><\/ul>\n\n\n\n
Post-emergent herbicides come in two forms -- granular and liquid.<\/p>\n\n\n\n
When to apply post-emergent herbicides\u00a0<\/h2>\n\n\n\n
When should you apply a post-emergent herbicide? The short answer is whenever you see weeds in your yard. The longer answer? Time of year and time of day are important factors when applying post-emergent herbicides to ensure they will be most effective. <\/p>\n\n\n\n
Time of year<\/h3>\n\n\n\n
The best time of the year to apply post-emergent herbicides is in early to late spring, <\/strong>when weeds are small but actively growing, as they will more easily absorb weed killer.<\/p>\n\n\n\n
Peak time in spring to apply post-emergent herbicide is when the daytime temperature<\/a> is under 85 degrees, and the soil temperature is above 55 degrees for at least three days. <\/p>\n\n\n\n
You can apply post-emergent products until late summer,<\/strong> but once the outside temperature exceeds 85 degrees, it usually takes more than one application to kill the weeds. <\/p>\n\n\n\n
Pro Tip:<\/strong> Wait until your grass has recovered from drought or disease before applying a post-emergent, as stressed-out weeds can struggle to take in any weed killer.<\/p>\n\n\n\n
Time of day\u00a0<\/h3>\n\n\n\n
The best time of day to apply your post-emergent is morning<\/strong> when weeds are growing at their fastest rate. Weed growth slows later in the day and evening, so it will take longer for post-emergents to be absorbed and effective. <\/p>\n\n\n\n
Check the weather: <\/strong>If a rainstorm is predicted the day you plan to kill weeds, either apply the herbicide early enough to dry before the rain shower or wait until the next dry day. <\/p>\n\n\n\n
Pro Tip:<\/strong> Avoid spraying post-emergent herbicides on windy days, especially if you\u2019re using a non-selective treatment for two reasons: You can end up with an uneven application, and you may kill plants you were trying to avoid. <\/p>\n\n\n\n
How to apply post-emergent herbicides\u00a0<\/h2>\n\n\n\n
There are two methods to apply post-emergent herbicides: blanket or spot treatment. <\/p>\n\n\n\n
Which one is right for your yard? <\/p>\n\n\n\n
Blanket treatments<\/strong> are excellent for yards covered in weeds. <\/p>\n\n\n\n
Spot treatments<\/strong> are great for lawns with a few weeds and work well along sidewalks and driveways.<\/p>\n\n\n\n
Blanket treatments\u00a0<\/h3>\n\n\n\n
What you\u2019ll need <\/strong>depends on whether you choose a granular or liquid post-emergent: <\/strong>To apply a granular post-emergent, you will need a spreader (similar to a wheelbarrow). To apply a liquid post-emergent, you will need a sprayer tool. <\/p>\n\n\n\n
Blanket application is best used with selective post-emergents, otherwise, you can easily kill your entire lawn. Also, because you\u2019ll be applying a post-emergent across a wide area, you\u2019ll need more herbicide, which can be a pain as blanket treatments tend to cost more than spot treatments.<\/p>\n\n\n\n
How to apply a blanket post-emergent: <\/strong>Spread or spray the post-emergent herbicide by going back and forth over the entire area. The goal? An even application of the post-emergent across your yard.<\/p>\n\n\n\n
Water in post-emergents:<\/strong> Granular and some liquid post-emergent herbicides will need to be watered in after application. Follow the directions on the herbicide label as the time frames for watering differ greatly. For example, you should wait at least 30 minutes and up to 8 hours to water in various herbicides.<\/p>\n\n\n\n
Pro Tip: <\/strong>Add <\/strong>a spray indicator dye to your post-emergent herbicide to ensure an even application across your lawn. <\/p>\n\n\n\n
Spot treatments\u00a0<\/h3>\n\n\n\n
Spot treatments of liquid post-emergents require a steady hand but can save you time and money<\/a> over blanket treatments. Spot treatments usually involve selective herbicides. If you see dandelions in your yard, for example, apply a dandelion killer.<\/p>\n\n\n\n
What you\u2019ll need:<\/strong> A sprayer tool and most liquid herbicides come with one. You also will need to read and follow label directions to mix the weed killer with water accurately.<\/p>\n\n\n\n
How to apply spot treatments<\/strong>: Spray your post-emergent herbicide right on the weed and move on to the next one. If you use a non-selective post-emergent, apply it only on the weed, or you also will kill surrounding grass and plants. <\/p>\n\n\n\n
Pro Tip:<\/strong> Wait until your grass has recovered from drought or disease before applying a post-emergent, as stressed-out grass and weeds can struggle to take in any weed killer.<\/p>\n\n\n\n
When to mow your lawn after applying herbicide<\/h3>\n\n\n\n
After applying your post-emergent herbicide, wait at least three days before mowing your lawn. This allows the weeds to grow a bit and fully absorb the herbicide before being cut. <\/p>\n\n\n\n
Weeds killed by post-emergent herbicides<\/h2>\n\n\n\n
Some weeds homeowners can eliminate with post-emergent herbicides include:<\/p>\n\n\n\n
- Contact post-emergent herbicides<\/strong> leave a coating on the plant to prevent photosynthesis. <\/li>
- University of Florida IFAS Extension<\/a><\/li> <\/ul> <\/div> \t\t<\/div> <\/div>
- Fertilize correctly<\/a>. Choose your fertilizer based on the results of a soil test<\/a>. Giving your lawn the right nutrients at the right time helps it grow thick and strong. <\/li>
- For granules<\/strong>: Watering activates them and helps them stick. Don\u2019t overwater, or it will wash them away.<\/li> <\/ul>
- For liquids<\/strong>: Only water if the packaging says so and within the timeframe indicated (usually a few hours). Not all liquid products require watering. <\/li>
- Work systematically through the marked areas.<\/li> <\/ul>
- Aim the sprayer directly at the weeds you want to eliminate. Spray them until the leaves are saturated, but avoid excessive runoff<\/a>. <\/li>
- A broom and dustpan to pick up leftover granules from your driveway or walkway<\/li> <\/ul> <\/li> <\/ul>
- Then, gather protective gear (gloves, long-sleeved clothing to minimize skin exposure, eye protection, mask), marker flags, hose or sprinkler system<\/a>, and cleanup supplies (soap, water, and possibly a change of clothes) <\/li>
- First, identify the weeds in your yard and purchase a herbicide that targets them<\/a>. <\/li>
- 7 Best Post-Emergent Herbicides of 2024<\/a><\/li> <\/ul>
- Granular post-emergent<\/a><\/li><\/ul><\/li>
- Before you start<\/a><\/li>