No lawn is immune from weed growth. Weeds like to invade bare or thin areas of lawn. They will find a small spot, push their way through and try to take over.

Pre-emergent herbicides are very effective for treating weeds like crabgrass, clover, dandelions and thistle.

If you do more for your lawn than just a weekly mow, a vibrant green lawn is important to you. Besides basic weed control, overseeding is also something you can do to fight weeds.

But, can these two things be done together? Read on to find out.

What are pre-emergents?

The word pre means before. These types of herbicides are mean to kill weeds before they emerge from the ground. If you already see weeds in your lawn, you should be using post-emergent products.

Pre-emergents stop germinated seeds from establishing roots. When used correctly, pre-emergent herbicides are very adept at controlling weeds.

Pre-emergents and seeds

Pre-emergent herbicides work by covering weed seeds with a chemical and not allowing the roots and shoots to push through.

Fall and late winter are the times of year that most homeowners put down pre-emergent products. It is also common to overseed your lawn in fall, but some people do overseed in late summer as well.

This brings up the question, if pre-emergents kill weed seeds, will they also kill grass seeds? The answer is yes.

Pre-emergent herbicides will cover and create a chemical barrier around any seeds they come in contact with, weed and grass seeds alike.

Pre-emergent timeline

Worker spraying lawn.

Overseeding and using pre-emergent products should occur 12-16 weeks apart from one another.

Simply put, if you use pre-emergents, wait 12-16 weeks before overseeding. If you have already overseeded, wait 12-16 weeks before using any type of pre-emergent herbicide.

Fertilization and weed control is a service we offer at Evergreen Lawn and Landscape. Let us help you get that lush, green lawn you’ve been dreaming about.

Common weeds effectively controlled with pre-emergents

  • Crabgrass
  • Clover
  • Dandelions
  • Thistle


Clump of crabgrass.

Crabgrass is hands down, the most common weed that people use pre-emergent products for. It is one of the most problematic lawn weeds.

One plant can yield 150,000 seeds. Once one crabgrass weed has developed, it will not take long before your lawn is completely covered in crabgrass.

Post-emergent herbicides are not usually effective at treating crabgrass. This is why proper use of pre-emergent products is critical.


Clover broadleaf.

Clover is an interesting plant because it can be seen as a weed or as a groundcover. Some homeowners prefer a uniform look across their lawn, which is not possible with clover growth.

If you are not a fan of clover, you’ll be pleased to hear that it responds well to herbicides. It is drought resistant and cold hardy.

Clover spreads quickly and has a deep root system. Because of that, it is best to treat clover with pre-emergent herbicides. You want to stop the problem before it begins.



While children across the globe love when they discover dandelions growing, lawn enthusiasts do not. Dandelions are an extremely troublesome weed because they flourish, literally everywhere.

They have adapted to extreme weather conditions such as heat and drought. You’ve probably even seen dandelions growing out of cracks in sidewalks before.

There can be up to 200 seeds in each flower and when the wind blows, the seeds spread fast. For this reason, it is recommended to treat dandelions with pre-emergent products.



Thistle is a weed that causes instant misery for homeowners. They have sharp, prickly stems, along with dense roots that are a headache to hand-pull.

This weed invades quickly and will rob the nutrients and sunlight away from your lawn. If you have pets, thistle weeds can hurt and injure them as they run across your lawn.

Using a pre-emergent herbicide will halt thistle seeds before they germinate and cause major problems.

Tips for using pre-emergent products

  • Apply on dry lawns
  • Water well after application
  • Use more water with granular herbicides to ensure thorough saturation
  • Timing is everything, if you apply too late, pre-emergents will not work
  • Distribution of product needs to be uniform and even
  • Calibrate your equipment correctly

Call Evergreen Lawn and Landscape today to set up a seasonal planting service. We will make your yard pop with color.

Wrapping Up

Lawn care Landscaping.

Every homeowner that cares about their lawn should have basic knowledge and understanding of pre-emergent herbicides.

Achieving a healthy and lush lawn requires many things such as weed control, fertilization, and regular lawn maintenance.

Evergreen Lawn and Landscape has been providing exceptional lawn care services to our clients for over 30 years. We would love to put our knowledge to good use with your lawn today.