How To Sterilize Soil: 6 Ways To Eliminate Diseases And Bugs

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Whether growing small plants in a pot by your window or preparing for your new outdoor crops season, you might wonder how to protect your soil against potential diseases and bugs. If this is the case, sterilization can be the answer to your question. 

Sterilizing eradicates harmful microorganisms in the earth and keeps your plants healthy. If you don’t know how to sterilize soil properly, read on to discover!

Soil Sterilization – An Overview

What Is Soil Sterilization?

Soil sterilization is a farming technique that eradicates weed roots, fungus gnats, mites, and other diseases and bugs. Sterilization protects your crops from being destroyed by plant diseases and allows healthier plant growth. This process is popular among commercial greenhouses, farmers, and agricultural sectors. 

There are pros and cons specific to each sterilizing method. But as long as you carefully follow the procedures, you can minimize the harm and bring the most out of sterilization for the entire garden. 

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What Are The Benefits Of Soil Sterilization?

First and foremost, sterilization is cheaper and less time-consuming. It costs less than disease treatments and reduces the need for regular soil replacement. This technique is especially helpful for greenhouses that want to reuse earth and for farmers with expensive crops. 

If you need to grow seed and stem, cut shoot, or transplant juvenile plants, the last thing you want is harmful organisms and fungal diseases in non-sterile soil infecting your garden. In such cases, sterilization for fresh soil comes off as a big help. 

Does Soil Sterilization Harm Your Garden?

In short, yes, it does. Sterilization doesn’t discriminate, so it also wipes out the good bacteria and beneficial soil organisms that bring nutrients to the plants. Besides, strong and mature plants can withstand unsterilized earth, making sterilization redundant for gardens of this crop type. 

 know how to sterilize soil
Sterilization protects your crops from being destroyed and helps grow healthier plants.

How To Sterilize Soil – The Six Ultimate Methods

Sterilizing Soil Using Chemical Treatment

The basis for chemical sterilization is gas: you let the unsterilized soil absorb the gas from the chemical to kill the bacteria. This method takes less effort and works well on outdoor fields. However, it can be harmful and ineffective if not done carefully. 

The two most popular chemicals used for this technique are hydrogen peroxide and formalin.

Hydrogen Peroxide

Hydrogen peroxide, though relatively safe, can still harm your skin and therefore requires careful use. It needs to be watered down before applying to the earth, and the denser the solution is, the less you should use. 

Nevertheless, this method is advantageous for its simplicity. You will only need two steps to carry it out: 

  1. Mix hydrogen peroxide with plenty of water. How much hydrogen peroxide you need depends on how much water you have and how dense the solution is. Several HP solutions are on the market, but the most popular ones come with 3% and 35% concentrations. 
  2. Apply the solution to the layers of soil.


Formalin is diluted formaldehyde, which works well against fungus but not as much against pests like gnats. Like the previous chemical, formalin-based sterilization is pretty straightforward, with only three steps: 

  1. Add formalin to hot water using the ratio of 1 part formalin 38%-40%, 49 parts water. 
  2. Apply the mixture to the houseplant soil. The more thoroughly it’s done, the better it is. Ideally, you should aim for 5 gallons of diluted formalin per square yard. 
  3. Wait for 20-40 days for the sterilization to take part. 

Keep in mind that you should use formalin under warm conditions since this chemical does not fumigate at low temperatures.

Sterilizing Soil Using Heating Methods
Chemical sterilizing is a simple and effective method.

Sterilizing Soil Using Heating Methods

Heat-based sterilization is an environment-friendly, effective and accessible method for anyone. However, it’s more tedious than chemical sterilization and doesn’t work well with large outdoor fields. 

The four popular devices used in this category are microwaves, ovens, steams, and the sun. 


For this method, you will go through 5 steps: 

  1. Place some cups of water in a stockpot or pressure cooker. 
  2. Fill a container with earth and use aluminum foil to cover the top. Then, put the container on a rack in the pot with water beneath. 
  3. Put the lid on the pot or close the steam valve of the pressure cooker. Then, begin boiling the water. 
  4. If you’re using a stockpot, wait for 30 minutes. If you’re using a pressure cooker, let it sit at 10 pounds of pressure for 15-30 minutes. 
  5. Turn off the heat and wait until the soil has cooled down to remove it. 


These are four steps to sun sterilization. If you are working on an outdoor garden, you can skip steps 1 and 2. 

  1. Identify a land area that receives at least 8 hours of sunlight per day. 
  2. Put a large sheet of plastic on the area and spread the dirt onto the sheet. 
  3. Moisturize the soil and place the second sheet of plastic on it. Hold down the sheet with rocks to make a seal. For gardeners, burying the sheet corners can work as well. 
  4. Wait several weeks for sterilization to take place. The hotter the weather is, the less you will have to wait. 

Tips For Better Soil Sterilization

Using An Oven

There are seven steps for this method: 

  1. Preheat the oven to 180 degrees Fahrenheit. 
  2. Put the ground on the roasting pan or baking sheet until it reaches 3-4 inches deep. 
  3. Moisturize the soil until it can be rolled into a ball. Break up the clumps to create a smooth surface. 
  4. Poke a hole in the aluminum foil and use it to cover the baking sheet. The hole makes space for the thermometer later in the process. 
  5. Heat the ground in the oven until it reaches 180 degrees. You should use a thermometer to track the temperature. Make sure not to let it get over 180 degrees since it will burn and produce toxins. 
  6. Leave the ground in the oven for 30 minutes. Occasionally adjust the temperature or open the door to control the heat. 
  7. Take the ground out of the oven and let it sit at room temperature. 
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Microwave Application

The steps for microwave sterilization are as below: 

  1. Put damp soil mix into a container or a thick plastic bag. 
  2. For the container, cover it with a lid with ventilation holes. For the bag, keep it open. Put both into the microwave. 
  3. Microwave for 90-150 seconds. 
  4. Measure the ground’s temperature, which should be around 180-200 degrees Fahrenheit. 
  5. If it has reached the right temperature, take it out of the microwave. Then, seal the bag or the container lid’s holes. 
  6. Let the ground sit under normal temperature. 

Microwaving is perfect if you want to sterilize a small amount of earth, but not if you’re working on large gardens. 

Tips For Better Soil Sterilization

Some Final Tips For Better Soil Sterilization

Before sterilizing, don’t add fertilizers to your ground since this might reduce the effectiveness of the process and potentially harm your garden. After the process, there are also a few things you can do to keep your soil free of diseases and bugs:

  1. Rotate crops regularly to prevent pests.
  2. Take up healthy garden maintenance habits like testing the ground pre-fertilization, using sufficient compost, and avoiding disrupting the earth. 
  3. Sterilize your equipment at the start and end of each season.


Sterilization eliminates bugs, pests, and bacteria harmful to your garden through chemical or heat treatment. This technique is useful for every outdoor and indoor plant hobbyist, particularly those who need fresh land to germinate plants. 

Healthy ground makes for healthy crops. If you find this article on how to sterilize soil useful, make sure to follow us for future posts! 

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