Can You Mix Liquid Fertilizer With Insecticide?

If unwanted insects and pests are getting into your soil and plants, the best thing to use is insecticide. But if you also need to apply fertilizer to the lawn, you may be wondering if you can mix the two to save time.

You can mix liquid fertilizer with insecticide, but it’s essential to follow the instructions on each of the packets when it comes to measurements. You want to make sure you use the correct amount of fertilizer and insecticide. Some products don’t mix well together, so it’s best to do a test first.

The rest of this article will discuss mixing liquid fertilizer with insecticide in greater detail. It will also discuss whether it’s safe to do it and the benefits and downsides of mixing them.

Is It Safe To Mix Liquid Fertilizer With Insecticide?

It is safe to mix liquid fertilizer with insecticide once you follow the instructions on the packaging of each product. If you use too much of something, it will be dangerous for the plants. 

A problem that can occur if you apply too much insecticide to your plants is pesticide burn. Although pesticide burn can happen when using pesticides, it can also happen when you use insecticides specifically.

Symptoms of pesticide burn include:

  • Leaf spotting
  • Scorch
  • Blotchy plants

This problem affects the health and appearance of the plants, so you want to avoid it at all costs. It would be best if you didn’t run into any issues by using insecticide appropriately and measuring it before adding it to the fertilizer.

Too much fertilizer can cause discoloration in plants. It can also cause health problems that begin at the roots of plants. 

It’s easy to mismeasure products when mixing them, so you need to be extra vigilant.

How To Mix Liquid Fertilizer With Insecticide

It’s relatively easy to mix liquid fertilizer with insecticide. However, it’s always good to do a small test first to ensure it works and the products can blend well together. In some cases, the chemicals may not integrate well, and there may be some separation.

These are the most critical steps for mixing liquid fertilizer with insecticide:

  1. Check the individual labels.
  2. Prepare the mixtures separately.
  3. Add them together and apply them to the soil.

Below I will discuss each of these steps in more detail.

1. Check the Individual Labels

Firstly, you want to read the labels of the insecticide and fertilizer. This will tell you the measurements of each, which is key to protecting the health of your plants.

If you use too much fertilizer or insecticide, you could harm the plants. If you use too little, it will ultimately be a waste of time and product.

2. Prepare the Mixtures Separately

When preparing the mixtures, you should do so separately. More specifically, prepare the liquid fertilizer in a separate container from the insecticide. Since both products may need to be diluted to different degrees, it’s important not to skip this step.

If the substances have different dilution needs, you won’t be able to use the correct measurements if you mix them. This could damage the growing environment and cause harm to your plants. Or, it may end up wasting your time entirely!

3. Add Them Together and Apply Them to the Soil

Once you’ve prepared the liquid fertilizer and insecticide separately, you can add them together. Ensure they’re mixed well before use to ensure the best results. 

Once the mixture is ready, you can use it as a regular fertilizer. Make sure to spread it across your plants or the lawn without missing any spots.

Should You Apply Fertilizer and Insecticide Separately?

You should apply fertilizer and insecticide separately if you have the time and want to ensure your plants and lawn remain healthy. However, if you want to save time and you know how to mix them correctly, you can combine them.

If you want to apply them separately, you can use one after another. First, you should apply fertilizer to the soil. Afterward, you can apply the insecticide. 

Of course, this will double the time it takes to apply them, but it ensures you get each measurement as accurate as possible. It also means you don’t have to worry about some chemicals not mixing well together and separating.

The Benefits of Mixing Liquid Fertilizer With Insecticide

There’s no doubt that there are positives and negatives to mixing liquid fertilizer with insecticide. 

Before you take the plunge and decide to mix them together, you should know the main benefits and downsides; this will help you become more informed and educated on the topic.

Below, I’ll discuss the main positives of mixing liquid fertilizer with insecticide.

Saves Time and Energy

When you mix pesticide with insecticide and apply them to the soil simultaneously, you’re saving yourself a lot of time. This is especially true if you apply them to a large lawn. If you use them separately, it will take you at least double the amount of time.

On top of that, mixing the two products also saves you energy. Going up and down the garden can be exhausting, and doing it twice is even more tiring! By mixing them, you only need to make one trip around the garden, giving you the energy to do other things.

Beneficial for the Soil

Applying insecticide and liquid fertilizer together is good for soil and plants because you’re feeding them nutrients while killing and preventing insects at the same time. 

Still, this is only true if you apply them correctly and don’t use too much or too little of either one. If you want the mixture to be as beneficial as possible, be sure to use the correct dilutions before adding them together!

The Downsides to Mixing Liquid Fertilizer With Insecticide

Since I’ve discussed the main upsides of mixing liquid fertilizer with insecticide, I also want to discuss the downsides. I’ve already briefly addressed that some products may not mix well together, so I’ll explain that in more detail.

Be sure to read these points before you mix the two products.

The Products Might Not Mix Well Together

Many insecticides have ingredients that separate, which can look similar to a bottle of salad dressing. It’s important to mix your insecticide before adding it into the fertilizer, especially if it’s separated. If you combine it while some of the ingredients are separated, it won’t mix well with the fertilizer, causing problems.

When using the products separately, you don’t have to worry about separation as much. Still, it’s something you should always consider if you want to apply liquid fertilizer and insecticide together.

Some Products Have Different Temperature Requirements

Another thing to consider is temperature requirements. For example, the fertilizer you’re using might have different water and temperature requirements than the insecticide. This means that if you mix them, they might not work very well together because one of them will be at the wrong temperature.

To check this, you should check the package of each product. You should be able to find information there regarding temperature and water requirements.

It’s Easier To Get the Measurements Wrong

When using liquid fertilizer and insecticide separately, it’s easy to follow all the required measurements. But when you’re mixing two or more products, it can get a lot more complicated. Generally, the more substances you mix, the more likely you are to make mistakes.

Because of that, you need to be extra careful when mixing fertilizer with insecticide. If you’re unsure of how much of the products to incorporate, it’s best to apply them to the soil separately. You certainly don’t want to risk damaging your plants or soil!

Can You Mix Insecticide and Weed Killer?

You can mix insecticide and weed killer, but only if they are compatible. Some products may not mix well together and might not be effective as a result. It’s best to use insecticides and weed killers separately to ensure the best results.

Before you mix them, you should perform a test to see how they react to each other. You may also need to combine them in a specific order, so it’s essential to check the individual packaging labels to see how to proceed.

If you get the mixture wrong, you may cause damage to your crops, plants, and soil.

Can You Mix Different Insecticides?

You can mix different insecticides, but it’s not the best idea. Since many insecticides (and pesticides in general) have physical and chemical incompatibilities, combining them can cause severe problems in your garden.

According to a study by Oregon State University, chemical incompatibilities are more common than physical ones. When a chemical incompatibility occurs, either one or both materials become stronger, but the reaction can also be negative.

If the materials are incompatible and their strength increases, this can negatively affect your plants.

For that reason, you should only mix different insecticides if you know exactly what you’re doing and if you’re sure the materials are compatible. In many cases, the insecticide package will tell you which other materials you can mix it with.


You can mix liquid fertilizer with insecticide, but you need to read the labels carefully before mixing them. To ensure you get the best results, you should prepare each material separately before mixing them.

If you’re unsure how to mix them or worry about getting the measurements wrong, you should apply the liquid fertilizer and insecticide separately. 

Mixing fertilizer and insecticide saves you time and energy, so it’s a good idea if you know how to do it. However, this can be damaging to plants if you mix them incorrectly. Always do a test beforehand.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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