Pre-Emergent vs. Post-Emergent Weed Killers

Key Takeaways

Effective weed management strategies:
  • Pre-Emergent Herbicides: Applied before weeds emerge to prevent germination and establish a chemical barrier in the soil.
  • Post-Emergent Herbicides: Target existing weeds by killing them at the root level, best applied when weeds show active growth.
  • Decision Making: Choice between pre-emergent and post-emergent herbicides depends on whether you're preventing weeds or treating existing ones.
Check out our pre-emergent and post-emergent weed control services.

When it comes to weed killers, there are two types of killers that you may encounter - pre-emergent and post-emergent. Here's a look at the differences between the two.

Pre-Emergent Herbicides

Pre-emergent herbicides are applied before weeds emerge from the soil. These herbicides prevent weed growth by preventing germination, or the process of a seed sprouting and growing into a plant. Pre-emergent herbicides are typically applied in early spring when weed seeds are most likely to germinate.

Pre-emergent herbicides create a chemical barrier in the soil that prevents weed seeds from germinating. The chemical bonds with particles in the soil, forming a barrier that stops weed seeds from sprouting. Therefore, pre-emergent herbicides are most effective when applied before weeds have a chance to sprout.

Post-Emergent Herbicides

On the other hand, post-emergent herbicides target existing weeds that have already sprouted up in your yard. These herbicides work by killing off existing weed plants at their root level, preventing them from spreading and taking over your lawn. Post-emergent herbicides are usually applied in late summer or early fall when weeds are most active.

The chemicals work by inhibiting the growth of these plants, keeping them from taking over your lawn or garden. The weed killer travels down the plant stalk, entering the root system to kill the weed. Post-emergent herbicides also work on perennial weeds.

To be successful with post-emergent herbicides, weeds must be actively growing and demonstrating visible signs of life. This includes growth, leaves changing color or shape, and flower stalks emerging from the soil. If you see any of these signs, begin application immediately to ensure maximum effectiveness.

Making The Right Decision For Your Lawn

When it comes to choosing between pre-emergent and post-emergent herbicides, it’s essential to consider your specific needs and the type of weeds you’re dealing with. Pre-emergent herbicides are a great choice if you’re looking for long-term protection against weeds. However, post-emergent herbicides are the way to go if you’re dealing with existing weeds.

Call In The Professionals

There is a reason people say “pesky weeds.” Dealing with weeds in your yard and garden takes time, and deciding when to apply which application of weed killer and fertilizer can be difficult. Knowing which type of product to use for your particular kind of grass is also important. 

We at Cory’s Lawn Service have provided the most high-quality care in the Reno/Sparks area since 2006. We are focused on delivering top-notch customer service, maintaining beautiful lawns, and giving our customers more time to spend on what is most important.

As Spring approaches, contact us today and have our trained team provide you with a free estimate on your fertilization needs, including pre-emergent and post-emergent weed killers