Pre emergents are weeds and other undesirable plants that have not yet emerged from the soil. Pre-emergent herbicides usually work on specific plants (weeds) to keep them from growing before they emerge from the soil. They are used chiefly where desirable plants or grass have been established.

There are pre-emergent products for lawns, vegetable gardens, and flower beds. Applying them too early can keep the plants you want from growing and desired plants sprouting. On the other hand, applying too late won’t do any good. 

Some landscaping jobs are better left to the pros, even if you are an experienced gardener. Your landscape and garden partners at Divine Lawns will know when to apply pre-emergent herbicides for the best results.

What to look for

There are two primary forms of pre-emergent herbicides – liquids and granules. Although they work the same way – they prevent weeds from emerging from the ground, some people prefer one over the other.

Most pre-emergent herbicides target plants by stage rather than specific plants. So, while they might prevent seeds from developing roots, they won’t harm the roots of a larger plant.

Pre-emergent herbicides stop weed seed germination. 

Remember – pre-emergent herbicides will not be able to control existing weeds or weed seeds. Weeds are only killed when they sprout from the seed. Therefore, it is possible for some seeds to remain dormant and not be harmed at all by the pre-emergent herbicide.


Read the label! Herbicides all have a warning since misuse can endanger humans, animals, and the environment.

If pre-emergent herbicides contact the skin or are accidentally inhaled, it can cause respiratory problems or skin irritation. Cover up when using pre-emergent pesticides, including gloves, long sleeves, long pants, dust mask, and eye protection.

Choose a calm day to apply. This is more important with the liquid type than with the granules. Wind can carry the spray and reduce good coverage in the desired area.

Wash your skin and face after the application of a pre-emergent herbicide. Some herbicides may have landed on skin and clothing, so thoroughly wash both skin and clothing.

When to apply

Setting a specific date to apply a pre-emergent herbicide probably won’t work out. A lot depends on when winter ends where you live.

It’s best to apply pre-emergent herbicides when the soil temperature has reached 55 degrees for several days. This will vary from one part of the country to another. In the southern part of the country, those temperatures will occur by around the beginning of March, but in the north, you may not see those temperatures before June.

It might be good to apply the pre-emergent herbicide when the soil temperature starts dropping in the fall. Once the soil temperature reaches about 55 degrees, the soil is cooling to the temperatures that encourage cold-weather seeds to sprout.

Remember, reseeding a lawn too soon after applying a pre-emergent herbicide may keep grass seeds from sprouting. Many lawn care professionals reseed grass to keep it full and lush later into the season. However, after using a pre-emergent herbicide, you will have to wait at least eight weeks to reseed or overseed a lawn.

What if I already have weeds on my lawn?

How many weeds do you have? If there are only a few, you may be able to dig them out with your hand tools. Make sure you get the roots and thoroughly remove them!

If your lawn is already full of weeds, you will have to know what kinds of weeds you have to make a plan to work with specific weeds. 

Choose your poison!

Choosing the proper treatment can be a daunting task based on weed classification and the life cycle stage of the weeds.

Herbicides can kill any plant life they contact, even the plants you want to keep. Killing your thinning grass isn’t much of a problem since you want to re-establish your lawn. However, if there is a significant weed problem and/or your grass is already on its way out, you will need to start fresh.

Apply the treatment

Follow the instructions exactly. Make sure you are applying the correct product at the proper time. Check the weather forecast – you don’t want all your hard work to be washed away. 

Remember, the herbicides will prevent grass seeds from growing and weed seeds. Sowing your seeds too soon would be a waste of seeds and effort. 

Check with your lawn care specialists at Divine Lawns. Depending on the type of treatment, you may have to wait as much as a month before you can reseed. This will require patience, lots of patience. Take this time to plan your next steps.

Dethatch and aerate

Once the weeds (and grass that was there) have turned brown, it’s time to rake up as much of the weeds as possible. Your tilling fork can pull extra weeds out and turn over the soil to prepare it.

You might find that your lawn had a growing thatching problem during the tilling process. If that’s the case, dethatching and aerating will help you get rid of, or reduce, the thatch layer to improve your lawn’s access to water, air, and nutrients.

When you get to this point, look around and ask yourself: how big IS this lawn? Dethatching and aerating using hand tools or push aerators is heavy work. You will need to make several passes with rented machines. Your lawn care pros will have the tools and machines to dethatch and aerate your soil. Let them do their jobs.

Seed or sod?

Seed can be less expensive and offer more variety, but sod gives you an instant lawn, requiring very little maintenance.

Whatever you choose, water generously after applying your seed or sod.

Again, rely on your pros at Divine Lawns to help make this decision.