Imagine this: You spend hours making your lawn look perfect. You water it just right. Then, suddenly, tiny green shoots pop up everywhere. These aren’t the grass you want; they are pesky weeds! Dealing with weeds after they sprout feels like an endless battle. It’s frustrating when your beautiful green carpet gets invaded.
Choosing the right lawn pre-emergent can feel like navigating a maze. Should you use granules or a liquid? When is the exact right time to apply it? Picking the wrong product or applying it too late means you’ll still be pulling weeds all summer long. We all want a thick, healthy lawn without the constant chore of weed control.
This guide cuts through the confusion. We will clearly explain what pre-emergent herbicides do and how they work. You will learn the simple steps to choose the best product for your yard and the perfect time to put it down. Get ready to stop weeds before they start!
Top Lawn Pre Emergent Recommendations
- Designed to prevent weeds; will not aid in eliminating existing weeds. Prevents grassy and broadleaf weeds, including crabgrass, poa annua, goosegrass, henbit, and more.
- Contains 0.48% of the active ingredient prodiamine for professional-grade weed control for early spring and fall applications
- Made with patented DG Technology (dispersible granule) ensures granules dissolve rapidly upon watering, moving weed control directly into the soil for maximum impact
- Small particles for more coverage per square inch and superior performance
- Made in the USA
- Designed to prevent weeds; will not aid in eliminating existing weeds. Prevents grassy and broadleaf weeds, including crabgrass, poa annua, goosegrass, henbit, and more.
- Contains 0.48% of the active ingredient prodiamine for professional-grade weed control for early spring and fall applications
- Made with patented DG Technology (dispersible granule) ensures granules dissolve rapidly upon watering, moving weed control directly into the soil for maximum impact
- Small particles for more coverage per square inch and superior performance
- Made in the USA
- Scotts Turf Builder WinterGuard Fall Weed & Feed3 is a weed killer and lawn fertilizer that controls weeds and feeds grass in the fall for a better lawn next spring
- Fall weed and feed kills over 50 listed lawn weeds, including clover, dandelion, plantain, morningglory, chicory, eveningprimrose, and purslane
- Apply weed control plus grass fertilizer to a moist lawn when weeds are actively growing and temperatures are consistently between 60°F and 90°F
- This lawn care product is for use on Bahiagrass, Bermudagrass, Bluegrass, Centipedegrass, Fescue, Ryegrass, and Zoysiagrass
- One 11.43 lb. bag of Scotts Turf Builder WinterGuard Fall Weed & Feed3 covers 4,000 sq. ft.
- Scotts Halts Crabgrass & Grassy Weed Preventer prevents the germination of listed lawn weeds so you can enjoy your lawn
- Prevents the germination of crabgrass, foxtail, spurge, barnyardgrass, and more as listed in the early spring all season long, and moss (except in California), Poa annua, henbit, corn speedwell, and chickweed in the fall
- Apply this pre-emergent weed killer in the early spring to a dry lawn or in the fall; rain, snow, or freezing weather after application will not affect the performance of this product
- This lawn care product is for use on all grass types (with the exception of Dichondra or Bentgrass)
- One 20.12 lb. bag of Scotts Halts Crabgrass & Grassy Weed Preventer covers 10,000 sq. ft.
- Prevent Weeds
- Effective Weed Prevention: Incorporating 0.37% PRODIAMINE into your lawn care routine ensures effective strategies for weed prevention, particularly targeting common weeds like crabgrass in the spring and poa annua (annual bluegrass) in the fall.
- Suitable for ALL GRASS TYPES: This product is suitable for use with various grass types, including Bahiagrass, Centipedegrass, Bermudagrass, Zoysia, St. Augustinegrass, Seashore Paspalum, and Tall Fescue (including turf-type), making it versatile for different lawn environments.
- CRABGRASS PREVENTION: It effectively prevents the growth of crabgrass, poa annua (annual bluegrass), and other common weeds, ensuring a healthier and cleaner lawn throughout the seasons.
- CANNOT SHIP TO MAINE OR IOWA**
- Scotts WeedEx Prevent with Halts prevents crabgrass all season long
- This pre-emergent grassy weed killer stops crabgrass before it starts
- Apply in early spring for season-long prevention of crabgrass, or apply in fall to prevent winter weeds such as Poa annua, henbit, and chickweed
- Do not apply this lawn care product to Dichondra and Bentgrass
- One 10.06 lb. bag of Scotts WeedEx Prevent with Halts covers 5,000 sq. ft.
- Scotts Halts Crabgrass & Grassy Weed Preventer prevents the germination of listed lawn weeds so you can enjoy your lawn
- Prevents the germination of crabgrass, foxtail, spurge, barnyardgrass, and more as listed in the early spring all season long, and moss (except in California), Poa annua, henbit, corn speedwell, and chickweed in the fall
- Apply this pre-emergent weed killer in the early spring to a dry lawn or in the fall; rain, snow, or freezing weather after application will not affect the performance of this product
- This lawn care product is for use on all grass types (with the exception of Dichondra or Bentgrass)
- One 10.06 lb. bag of Scotts Halts Crabgrass & Grassy Weed Preventer covers 5,000 sq. ft.
Your Guide to Choosing the Best Lawn Pre-Emergent Herbicide
Weeds can quickly turn a beautiful lawn into a messy patch. Pre-emergent herbicides stop weeds before they even sprout. Choosing the right one makes all the difference. This guide helps you pick the best product for your yard.
Key Features to Look For
When shopping for a pre-emergent, look closely at these features:
1. Active Ingredient Type
- Dithiopyr: This is a popular choice. It stops crabgrass and other annual weeds effectively. It often gives you a longer window of protection.
- Prodiamine: Another strong option. It works well against many grassy weeds. Some users find it lasts a bit longer than Dithiopyr.
- Pendimethalin: This ingredient is common. It controls a wide range of summer annual weeds.
2. Application Type
Products come in two main forms:
- Granular (Slow-Release): You spread these tiny pellets using a broadcast or drop spreader. They are easy to apply evenly. Rain or watering activates them.
- Liquid Concentrate: You mix this with water in a sprayer. Liquid products often work faster once applied, but you must ensure good coverage.
3. Lawn Safety (Turf Tolerance)
Make sure the product is safe for your type of grass. Some pre-emergents work great on cool-season grasses like fescue but might hurt warm-season grasses like St. Augustine. Always check the label for your specific grass type.
Important Ingredients and Materials
The active ingredient is the main thing that kills the weed seeds. However, the other materials matter for how you use the product.
Carrier Material (For Granular Products)
Granular products use a carrier material, often clay or sand, to hold the active ingredient. A good carrier spreads smoothly. Poor quality carriers might clump, making your application uneven. Uneven spreading leads to patches of weeds later.
Surfactants (For Liquid Products)
Liquids sometimes include surfactants. These help the herbicide stick to the soil and weed leaves better. Good adhesion means the chemical works where it needs to.
Factors That Improve or Reduce Quality
The quality of your pre-emergent success depends on timing and soil conditions.
Timing is Everything (Improves Quality)
Pre-emergents must be applied before the weed seeds germinate. For crabgrass, this usually means applying when soil temperatures consistently reach 50–55°F for several days. Applying too late means the weeds are already growing, and the product will not work.
Soil Disturbance (Reduces Quality)
These herbicides create a chemical barrier in the top layer of the soil. If you heavily till or rake your soil after applying the product, you break up this barrier. This allows dormant weed seeds below the surface to sprout easily.
Water Activation (Improves Quality)
Most pre-emergents need about half an inch of water soon after application. This moves the chemical into the top layer of the soil where the weed roots will meet it. If you skip watering, the product sits on top and loses effectiveness quickly.
User Experience and Use Cases
How easy is the product to use? Which situations require which type?
For Large Yards
Most users find granular products much easier for large areas. You can cover a lot of ground quickly with a spreader. It requires less mixing and cleanup than liquid spraying.
For Small Yards or Spot Treating
Liquid concentrates are often better for small, precise areas, like flower beds next to the lawn. They allow for very targeted application where you don’t want spreader drift.
Seasonal Needs
Most lawns need two applications per year. Apply the first in early spring (for summer annual weeds like crabgrass). Apply the second in late summer or early fall (for winter annual weeds like Poa annua).
10 Frequently Asked Questions (FAQ) About Lawn Pre-Emergent
Q: When should I apply pre-emergent herbicide?
A: Apply it in early spring before soil temperatures reach 50–55°F consistently. Apply again in late summer for fall/winter weeds.
Q: How long does pre-emergent last?
A: Most products last between 8 to 16 weeks, depending on the active ingredient and rainfall. Some professional-grade products last longer.
Q: Can I plant grass seed after using pre-emergent?
A: Generally, no. Pre-emergents stop all seeds from sprouting, including your new grass seed. Wait the time specified on the label, usually 8–12 weeks, before overseeding.
Q: What is the main difference between pre-emergent and post-emergent?
A: Pre-emergent stops weeds before they sprout. Post-emergent kills weeds that are already visible above ground.
Q: Do I need to water the product in after spreading?
A: Yes. You must water the granules in with about half an inch of water to move the chemical into the soil where it works.
Q: Is granular or liquid better?
A: Granular is often easier for beginners and large areas. Liquid provides better control for very small or difficult spots.
Q: Will pre-emergent kill my established lawn grass?
A: No, if you use the correct product labeled safe for your specific grass type (like Bermuda or Fescue). Always read the label!
Q: What happens if I apply pre-emergent when it’s already hot outside?
A: If it’s too late, the weeds have already sprouted, so the chemical will not work on them. High heat can also stress your lawn.
Q: Can I use pre-emergent near flower beds?
A: Be careful. If the herbicide washes or drifts into the flower beds, it may stop your flower seeds or bulbs from growing. Use liquid for precise edging.
Q: Should I fertilize at the same time as applying pre-emergent?
A: Many products combine fertilizer and pre-emergent. Applying them together saves time, but ensure the fertilizer is appropriate for the season.