Does Fertilizer Kill Weeds? Fertilizers and Weed Control

Maintaining a beautiful lawn or garden is every homeowner’s dream. However, this dream can quickly turn into a nightmare when pesky weeds start to invade your beautiful green space. Weeds are unwanted plants that grow in places where they are not supposed to be, and they can quickly spread and take over your lawn or garden if left unchecked. There are several ways to control weeds, such as pulling them out by hand, using herbicides, or applying fertilizer. However, many people wonder if fertilizer can kill weeds or not.

In this article, we will explore the truth about whether fertilizer can help you get rid of weeds or if it’s just a myth.

How Does Fertilizer Work?

Before we dive into the question of whether fertilizer can kill weeds, let’s first understand how fertilizer works. Fertilizer is a blend of nutrients that are essential for plant growth, such as nitrogen, phosphorus, and potassium. When applied to the soil, fertilizer helps to nourish the plants and promote healthy growth.

Can Fertilizer Kill Weeds?

Now, let’s answer the burning question: does fertilizer kill weeds? The answer is no, fertilizer does not kill weeds directly. Fertilizer is designed to provide nutrients to plants, and it does not have any herbicidal properties that can kill weeds.

However, this does not mean that fertilizer cannot help control weeds indirectly. Fertilizers can help to promote healthy plant growth, which can help to choke out weeds and prevent them from growing. When plants are healthy, they are better able to compete with weeds for sunlight, water, and nutrients, which can reduce weed growth over time.

Which Fertilizer Kill Weeds?

Weed and feed fertilizers are specifically designed to both fertilize plants and kill weeds. They contain both a fertilizer to provide essential nutrients for plant growth and a herbicide to control weeds. Some common weed-killer herbicides found in weed and feed fertilizers include 2,4-D, dicamba, and glyphosate.

It is important to note that not all weed and feed fertilizers are effective against all types of weeds. The effectiveness of the herbicide will depend on the type of weed and the stage of its growth. It is also important to use weed and feed fertilizers according to the manufacturer’s instructions and to avoid over-application, as this can lead to herbicide contamination and harm to beneficial plants and wildlife.

 How Do Weed and Feed Fertilizers Kill Weeds?

Weed killer fertilizers, also known as weed and feed fertilizers, are products that contain both a fertilizer and a weed killer herbicide. The herbicide in these fertilizers is designed to kill weeds while the fertilizer provides nutrients for the desired plants to grow. Here are the mechanisms by which weed killer fertilizers kill weeds:

1. Herbicide Contamination

Weed killer fertilizers contain herbicides such as 2,4-D, dicamba, or glyphosate, which are effective at killing broadleaf weeds. These herbicides work by interfering with the normal growth and development of the weed, causing it to die. When the herbicide is applied to the lawn or garden along with the fertilizer, it can be absorbed by the weeds and transported to their roots, ultimately killing them.

2. Nutrient Imbalance

Weed killer fertilizers can also indirectly kill weeds by creating a nutrient imbalance in the soil. Weeds are opportunistic plants that thrive in soils that are nutrient-rich but lack competition from other plants.

When a weed killer fertilizer is applied, it provides the desired plants with an abundance of nutrients, which allows them to grow stronger and outcompete the weeds for resources. At the same time, the fertilizer creates a nutrient imbalance in the soil, which makes it more difficult for weeds to survive.

3. Competition

Fertilizers can help the desired plants grow more vigorously and compete better with weeds for resources such as light, water, and nutrients. When a weed killer fertilizer is applied, it provides the desired plants with the nutrients they need to grow stronger and healthier.

This can allow the desired plants to outcompete the weeds for resources, ultimately leading to the death of the weeds.

4. Alteration of Soil pH

Weeds typically prefer slightly acidic soils, while many desired plants prefer slightly alkaline soils. Some weed-killer fertilizers are designed to alter the pH of the soil to make it more alkaline, which can make it more difficult for weeds to grow.

By altering the pH of the soil, these fertilizers can help create an environment that is more favorable to the desired plants, while making it more difficult for weeds to survive.

Limitations of Fertilizers in Killing Weeds

While fertilizers can contribute to weed control, there are limitations to their effectiveness in killing weeds. Some factors that can limit the effectiveness of fertilizers in killing weeds include:

  1. Weed species: Different weed species have varying levels of tolerance to fertilizers. Some weed species may be able to thrive even in the presence of high levels of nutrients.
  2. Timing of application: Fertilizers need to be applied at the right time for maximum effectiveness. Applying fertilizers too early or too late in the growing season can reduce their impact on weeds.
  1. Soil conditions: The effectiveness of fertilizers in killing weeds can be affected by soil conditions such as texture, moisture, and pH. For example, weeds may be more tolerant of fertilizers in soils that are too acidic or too alkaline.
  2. Application rate: Applying too little fertilizer may not have a significant impact on weed growth while applying too much fertilizer can lead to nutrient imbalances that can promote weed growth.
  3. Other weed management practices: Fertilizers should be used as part of an integrated weed management program that includes other practices such as tillage, crop rotation, and the use of herbicides.

Alternatives to Fertilizers in Weed Control

Several non-chemical weed control methods can be used as alternatives to fertilizers:

  1. Manual weed control: This involves physically removing weeds by hand or with tools such as hoes, weeders, or cultivators. This method can be effective for small-scale weed control, but it can be labor-intensive and time-consuming.
  2. Mulching: Applying organic mulch such as straw, wood chips, or leaves around plants can help suppress weed growth by smothering weed seeds and blocking sunlight.
  3. Cover cropping: Planting cover crops such as clover or rye can help suppress weed growth by competing for resources and shading out weed seeds.
  4. Crop rotation: Rotating crops can help disrupt weed growth cycles and reduce weed pressure over time.

Organic fertilizers can also be used as a weed control method. While they may not directly kill weeds, some organic fertilizers have weed-control properties. For example:

  1. Corn gluten meal: This organic fertilizer contains a natural herbicide that inhibits the growth of weed roots.
  2. Soybean meal: This organic fertilizer contains high levels of nitrogen that can help plants grow faster and outcompete weeds.
  3. Fish emulsion: This organic fertilizer contains high levels of nutrients that can help plants grow stronger and are better able to resist weed pressure.

How to Use Fertilizer to Control Weeds?

If you want to use fertilizer to control weeds, you should use it in combination with other weed control methods. Here are some tips on how to use fertilizer to control weeds:

How Long Does it Take for Fertilizer to Work

1. Choose the Right Fertilizer

Choose a fertilizer that contains pre-emergent herbicides. These herbicides will prevent weed seeds from germinating, reducing the number of weeds in your garden. However, be careful when choosing fertilizer as some herbicides can harm plants as well.

2. Time Your Fertilizer Application

Apply fertilizer before the growing season starts. This will give the fertilizer enough time to break down and release its nutrients into the soil. The nutrients will be available to plants when they start growing, giving them a head start over weeds.

3. Use Fertilizer in Combination with Other Weed Control Methods

Fertilizer alone is not enough to control weeds. You should use it in combination with other weed control methods like hand weeding, mulching, and herbicides.

Hand weeding is the most effective method of removing weeds, but it can be time-consuming. Mulching can prevent weed seeds from germinating by depriving them of light. Herbicides should be used as a last resort as they can harm beneficial insects and plants.


Fertilizer does not directly kill weeds. However, it can help to control weed growth indirectly by promoting healthy plant growth and competing with weeds for sunlight, water, and nutrients. Additionally, some fertilizers contain weed control additives, such as pre-emergent herbicides, that can help prevent weed seeds from germinating.

If you’re looking to use fertilizer to control weeds, be sure to choose the right type of fertilizer, apply it at the right time, and use the correct amount. And remember to always follow the instructions on the fertilizer label to ensure that you get the best results.


Is fertilizer with herbicide safe for my lawn and garden?

Fertilizers with herbicides can be safe if used correctly. It is important to follow the instructions carefully and apply the product as directed. Overuse or improper use can lead to damage to your lawn or garden, and can also be harmful to the environment.

What type of fertilizer kills weeds?

Fertilizers that contain a herbicide, specifically a pre-emergent herbicide, are designed to kill weeds before they germinate.
These types of fertilizers are often labeled as weed and feed products, as they provide both nutrients to plants and kill weeds at the same time.

Is It Safe to Use Fertilizer with Herbicides?

Fertilizers with herbicides can be safe when used correctly. However, they can be harmful if not applied correctly or if the instructions on the package are not followed. It is essential to read and follow the label instructions before using any fertilizer, especially if it contains herbicides.

How Often Should I Apply Fertilizer to Control Weeds?

The frequency of fertilizer application for weed control depends on the type of fertilizer and the weeds’ growth rate. It is recommended to apply fertilizer with herbicides as per the manufacturer’s instructions.

Leave a Reply

Your email address will not be published. Required fields are marked *