# How Do Pre-Emergents Work?

> Pre-emergent herbicides stop weeds before they sprout. How the chemical barrier works, when to apply it, and why timing matters.

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Published February 7, 2022. Category: Lawn Care Tips.

The short version: a pre-emergent herbicide creates a thin chemical barrier in the top layer of soil that stops weed seeds from developing into plants as they try to sprout. It does not kill weeds you can already see; it prevents the next crop. For that reason, pre emergent weed control is all about timing, applied before the target weeds germinate, watered in, and repeated on a consistent schedule. Here is how pre-emergent herbicides work and when to apply them.

Any good weed control program includes a pre-emergent treatment. To know how best to use a pre-emergent, you need to understand what pre-emergents are.

## Pre-Emergent Breakdown

Pre-emergents have a specific science behind them. We'll take a more detailed look at how pre-emergent herbicides work below.

A pre emergent weed killer does exactly what it sounds like it would do: it prevents weeds before they start growing.

- It stops weeds that have not yet emerged in your lawn's soil.
- A chemical barrier is created that absorbs into emerging seedlings and prevents them from sprouting.
- Targeted weeds are killed once they begin to sprout from the seed.

## Applying Pre-Emergents

Pre emergent weed control should be applied consistently. An annual pre-emergent works best for prevention of weeds, and some products combine a pre-emergent with feeding as a pre emergent fertilizer so the lawn is protected and fed in one pass.

Knowing when to apply pre emergent herbicide is half the job: put it down before the target weeds germinate, which in North Texas means late winter to early spring for summer weeds and early fall for winter weeds. To apply pre-emergents correctly you'll need to be specific on some details:

- You must mix the herbicide treatment correctly for it to do what it is designed to do.
- Make sure to follow the instructions provided by the manufacturer. This is mainly so you don't end up damaging your lawn.
- After the treatment is applied, you need to water the lawn.
- Lay down an even, effective spray of the pre-emergent for best results.

## Green Lawn Is Here to Help

Green Lawn Fertilizing is here to help with all your weed control and pre-emergent needs. If you don't use a pre-emergent, a weed-free lawn is still possible, but it does take longer to accomplish. Laying down a good pre-emergent before spring really assists in the overall appearance and health of your lawn.

Contact us today to schedule an appointment or get answers to your questions.

## Frequently Asked Questions

### How do pre-emergent herbicides work?

A pre-emergent herbicide forms a thin chemical barrier in the top layer of soil. As dormant weed seeds germinate and push a shoot up, they absorb the herbicide and stop developing before they ever emerge. It targets the seedling stage, which is why it prevents new weeds rather than killing established ones.

### When should I apply pre-emergent herbicide in North Texas?

Apply pre emergent weed control before the target weeds germinate. In North Texas that means late February to early March for summer weeds like crabgrass, and again in late September to early October for winter weeds like henbit and chickweed. Applied after those weeds have sprouted, a pre-emergent won't stop them.

### What's the difference between a pre-emergent and a post-emergent?

A pre emergent weed killer prevents weeds before they sprout by stopping seeds at germination. A post-emergent kills weeds that are already growing and visible. A complete program uses both: pre-emergent to prevent the next wave and post-emergent to clean up what's already there.

### Do I still need a pre-emergent if I fertilize?

Fertilizer thickens turf so weeds have less room, but it doesn't stop seeds from sprouting. That's why many programs use a pre emergent fertilizer that combines both, feeding the lawn while laying down the barrier that prevents weeds in the same application.


## Contact

- Phone: (469) 344-9619
- Email: john@greenlawnfertilizing.net
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