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Pesticides in a Greenhouse

Are Pesticides Used in Greenhouses?

Are you growing vegetables in a greenhouse? Are you having trouble dealing with pest and disease control? Are pesticides used in a greenhouse?

These are the common questions that greenhouse owners and managers ask at one point or the other during their process of maintaining a greenhouse. Greenhouses offer several benefits for growing plants and vegetables. From providing an environment to grow off-season crop, to allowing you to customize the conditions that you provide your plants, greenhouses offer it all.

However, as favorable as greenhouses are for plant production, they sometimes provide a favorable environment for pest and disease development as well. Although a few types of these conditions can be treated and eliminated by taking extra measures, some instances of pest and disease growth require a pesticide treatment. 

Can you use pesticides in a greenhouse?

Greenhouses usually maintain a warm and humid environment that allows for the abundant and healthy growth of plants and vegetables. The presence of these conditions, as well as food sources, encourage the growth of pests. Since the controlled environment of a greenhouse keeps the natural inhibitors of pests from growing, pests get a free pass to grow quickly and abundantly. It ends up causing severe damage to the crop.

Therefore, the use of pesticides becomes essential to control the development of pest buildup. To put it plainly, yes! Pesticides are used in a greenhouse. Pesticides include substances that help prevent, control, and reduce the growth of pests and harmful diseases in plants.  

Pesticides come in various types, each designed to target specific diseases and pests in the crops. Three of the most common ones include the following:

  • Insecticide: It targets different types of insects
  • Herbicide: It targets weed growth
  • Fungicide: It targets fungal diseases

How to use pesticides in a greenhouse?

When you feel the need for using pesticides in your greenhouse, there are a few things that you need to take into consideration for successful use. Let’s take a look at them in detail below.

Greenhouse label

The greenhouse label on the pesticide is what dictates its use. Label language informs you if the pesticide is suitable for use inside a greenhouse. It includes all the instructions and directions of use as well as a restrictions section. Not all pesticides are recommended for all types of crops. Each one is synthesized to be used on a specific plant at a specific growth stage.  

The use of pesticides is a sensitive matter because one small mistake can damage your crop. That is why some pesticide labels have different instructions for use inside and outside of a greenhouse. For instance, Streptomycin is only recommended for tomato transplants and prevents bacterial diseases in the crop only inside a greenhouse. However, it’s not effective or recommended for outdoor tomato crops.

Some pesticides may not have a restriction sign for greenhouse use and neither any instructions for use inside it. This indicates an implied use, but only if the label includes your target crop.    

Pesticide resistance

When you start using pesticides on your crops regularly, the pests start developing resistance characteristics. With extensive exposure to insecticides and fungicides, the pests start evolving genetically to resist the dose of pesticides that used to kill them before. The resistance genes formed as a result of genetic mutation, then transfer to the offspring and slowly spread across all the pests growing inside the greenhouse. The primary factor that contributes to the development of resistance is the repeated use of pesticides.     

With the continuous use of the same pesticide, more and more pests and insects develop resistance until the pesticide is no longer effective in killing or controlling their growth. That is one of the major challenges that most greenhouse gardeners face while growing crops.

How to manage Pesticide Resistance?

In order to prevent the development of pesticide resistance in pests, you need to formulate a plan for the effective use of pesticides. The effectiveness of a pest management plan depends largely on the effective application of pesticides.

Careful and well-planned application of pesticides ensures that no plant in your greenhouse gets infected with a pest that has developed resistance. It will also reduce the chances of pest resurgence, crop damage, secondary outbreaks, and harm to the environment and human caretakers.   

There are a few strategies that you can adopt to manage the development of pesticide resistance in your greenhouse. By implementing these, you’ll be able to minimize its development as well as protect your greenhouse plant crops. They are as follows:

1.    Integrated Pest Management Plan

Integrated pest management plan (IPM) is one of the most highly recommended strategies for managing pesticide use and resistance in greenhouses. IPM is an environmentally-sensitive approach that uses a combination of practices based on the latest knowledge on the lifecycle and growth of pests and their relationship with the environment.

It combines various common-sense measures and available pest management tools in a way that minimizes damage incurred by pests and the hazard to humans and the environment. IPM is the most sustainable, economic, and hazard-free approach towards pest control. It integrates the use of pesticides as well as alternative techniques to prevent pesticide resistance in greenhouses.    

Check out a Sample Integrated Pest Management Plan to get you started.

2.    Non-chemical Alternative Pest Management Measures

Just like the integrated pest management plan, it’s essential to adopt strategies and tools that consist of non-chemical and alternative pest control methods and measures. However, it’s important to ensure that these methods are effective on the pests infecting your plant crop in the greenhouse.  

3.    Avoid Using Persistent Chemicals

When you repeatedly use a persistent pesticide on a plant infected with pests, the resistant gene is selected to be transferred to the offspring instead of the susceptible ones. Chemicals that stay in the environment for prolonged periods allow the pests to develop resistance against them.

Therefore, an effective pesticide is the one that would rapidly vanish from the environment after killing the pests, so that they don’t have the opportunity to develop resistance against it.  

4.    Correct and controlled application of pesticides

It’s extremely important to make sure that you’re applying the pesticides correctly. You must follow the instructions given on the greenhouse label. Another method to temporarily hinder the development of resistance is by limiting pesticide application.    

5.    Proper spray coverage

One of the most efficient methods of reducing pesticide resistance is by enhancing the effectiveness of your pesticide application. This can be done by calibrating the application tools and equipment and maintaining them.

For proper maintenance, you should follow the instructions of use and recommendations on spray pressure, water volume, temperature, etc.  

6.    Pesticide Mixtures

Pre-formulated pesticide mixtures come with built-in resistance management characteristics. They have proven successful in various resistance control experiments on greenhouses.

7.    Incorporate Long-term Rotations

Incorporating long-term rotation strategies for pesticides increases their effectiveness period significantly. For instance, it is recommended to rotate the classes of fungicides after every application. In the case of insecticides, you can rotate the chemical class with every new generation of crops.

How to ensure human safety while pesticide application?

The primary purpose of pesticides is to prevent the growth of the pest population and manage their resistance without harming the environment of the greenhouse and the health of human workers. To ensure the safety of human farmers, customers, and any other visitors, it’s essential to take precautionary and safety measures.

Pesticides should have maximum exposure to target pests while minimum contact with humans and the environment. The use of pesticides in enclosed environments, such as greenhouses, can become hazardous for humans.

Therefore, the Environmental Protection Agency (EPA) has issued a list of measures and regulations that need to be implemented by greenhouse owners to ensure the safety of workers. The use of Personal Protective Equipment (PPE) is mandatory for workers responsible for the application of pesticides inside a greenhouse. Check out the protective measures and safety standards issued by the EPA here.


  1. Does greenhouse-grown mean organic?

According to the National Organic Program, all the vegetables and crops grown in greenhouses are certified as organic. It doesn’t matter if the crop is grown in a greenhouse hydroponically or the field soil, as long as it meets the standards and regulations set by the National Organic Program.

This is because greenhouse gardeners claim and ensure that their products are grown in accordance with the standards and without toxic pesticides.

  • Are pesticides used on greenhouse tomatoes?

Yes, pesticides are sometimes used on greenhouse produce, such as tomato crops. However, this use can be minimized by incorporating the Integrated Pest Management plan for pest prevention. IPMs usually limit the use of pesticides by incorporating non-chemical and biological alternatives.

The biocontrol measures include the use of natural agents to prey on the infecting agents in the greenhouse. However, for it to be effective, the natural agents will have to be released in the early stages of infection.

  • How do you control pests in a greenhouse?

You can control pests in the greenhouse by incorporating pest-control measures from the early stages. Integrated Pest Management Plan is one of the most efficient methods of maintaining crops and controlling infections. It’s essential to minimize the contact of outside infecting agents with the greenhouse crops.

More importantly, it’s crucial to adopt prevention strategies to effectively reduce the chances of infection to your crops, harm to the environment, and hazard to human workers.

  • Is greenhouse-grown healthy?

Yes, greenhouse-grown produce is just as healthy as the conventionally grown products. The greenhouse farmers don’t have to use fertilizers to make up for the poor condition of the soil. Additionally, the controlled environment allows the vegetables to grow under more scrutiny and free from environmental influence.


Greenhouses have unique challenges that arise due to the contained environment. Sometimes the same conditions that help the crop, also promote the growth of infecting organisms and pests. Therefore, pesticides have to be used in greenhouses to prevent the growth of pests, diseases, and other infections.

However, their use can be controlled and maintained by integrating different pest control measures and strategies, as discussed above.  

If you have any more questions, comments, or suggestions, please feel free to drop them in the comments below. We’ll be happy to hear from you and address as many questions as you may have!