How To Quickly Sterilize Garden Soil

More often than not, soil contains harmful bacteria and microorganisms. Therefore, you need to sterilize it from time to time. Luckily, soil sterilization is not as complex as most people think.

All you need is to determine the best soil sterilization method to use and all the steps involved. If you operate under tight schedules, you can also choose to purchase sterilized soil.

But this can be costly for you. So, let’s take a look at how to sterilize garden soil quickly.

The different techniques of sterilizing soil

First, it is essential to note that there are different techniques for sterilizing garden soil. Generally, gardeners can either use chemical treatment or heat treatment to sterilize the soil.

Commercial farmers often use chemical treatment. On the flip side, heat treatment is most common for residential gardens. Heat treatment involves exposing the soil to high temperatures to kill all harmful microorganisms and bacteria.

You can do this using solarization or baking the soil in an oven at 180 degrees Fahrenheit for half an hour. Steaming is also another heat treatment technique.

Sterilizing Soil with Steam

Experts consider steaming the best way to conduct heat treatment. When steaming soil, you can use a pressure cooker; but this is not compulsory.

If you decide to use a pressure cooker, fill it with water. Then, pour soil onto the cooker rack. Note that the height of the soil should not exceed 10 cm. Use foil to cover every pan.

Leave the steam valve open as you close the lid. This enables the steam to escape. Steam the garden soil for about 15 to 30 minutes. Be careful if you are dealing with soil rich in manure and nitrates. Such soil can be explosive when in contact with steam.

If you are not using a pressure cooker, pour some water into the sterilizing container. Fill pans with soil and cover them with aluminum foil. Place the pans on top of a rack positioned above the water.

Use a lid to close the container, but leave some space to allow heat to escape. Leave the container to boil for approximately 30 minutes. Afterward, leave the soil to cool and remove the foil.

Steaming is a pretty quick method to sterilize the soil. It only takes 30 minutes to an hour to complete this process.

Sterilizing Soil with an Oven

Another way you can sterilize your soil is by placing it in the oven. This method also takes 30 minutes to an hour. Thus, you need not worry about time. Below are the steps involved when sterilizing garden soil in an oven.

The first thing to do is to prep the soil for the entire procedure. Do this by removing all kinds of dirt and debris from the soil. Then put the soil in an oven-proof container. The soil should be about 4 inches deep. A baking pan works perfectly fine for this function. Cover the soil with foil.

Prepare the oven by preheating for about 15 minutes at a heat of 200 degrees Fahrenheit. Afterward, place the baking pan with the soil.

It would be best to put a meat thermometer at the center of the pan with the soil to monitor the soil’s temperatures accurately. Heat the soil for 30 minutes at a temperature of 180 degrees Fahrenheit.

Once you finish heating the soil, leave it to cool before using it.

Note that the soil should not exceed temperatures of 180 degrees Fahrenheit. Otherwise, the soil would produce toxins that can be detrimental to your plants.

Sterilizing Soil with a Microwave

The following technique of soil sterilization is using a microwave. If you decide to use this method, use microwave friendly containers filled with soil.

After filling soil in these containers, sprinkle some water to make the soil moist. Cover the containers with lids. Add several ventilation holes on the lid to prevent a build-up of excessive heat in the container.

Place the containers in the microwave and heat for approximately 90 seconds on full heat. If you have a big microwave, consider placing several containers in the oven.

Afterward, seal the ventilation holes and allow the soil to cool. You can also place the soil in a sealed plastic bag. Then, put it in the microwave and heat on full energy for two and a half minutes. Once you are done heating, leave the soil to cool.

The benefits of using sterile soil

When you sterilize your garden soil, it becomes free from all harmful microorganisms and bacteria. It is rare for sterile soil to pass pests and diseases on new plants than regular garden soil. If you plan to reuse soil, ensure you use sterile soil. Below are some of the advantages of using sterile soil.

Fosters healthy seed germination

Sterile soil is less compact. Hence, it promotes a faster breakdown of organic matter. This soil allows for healthy soil aeration. Thus, such kind of soil is good for germination especially if planting depth is also taken into account.

After germination, sterile soil also allows the roots to grow deep into the ground without any hindrances. Since sterile soil does not contain weeds, it fosters healthy plant growth.

Fosters healthy plant growth

Sterile soil enables organic matter to break down quickly into the soil. In turn, this increases the nutritional content of the soil. Sterile soil is usually richer in potassium, nitrogen, and magnesium.

As a result, growing your plants in sterile soil helps them grow strong and healthy. Strong and healthy plants are highly resistant to pests and diseases.

Therefore, you’ll end up obtaining a plentiful harvest at the end of the planting season if you use sterile soil. On the other hand, unsterilized soil is more likely to carry pathogens that adversely affect the plant’s health.

Saves on costs

Using sterile soil is also good since you’ll end up saving a lot of money. When using sterile soil, you are unlikely to encounter pests and diseases. Thus, you won’t spend thousands of dollars trying to purchase the right herbicides and pesticides.

Also, you would spend less time and effort trying to get rid of weeds if you use sterile soil. All in all, sterilizing yourself is cost-saving at the end of the day.


Sterile soil is environmentally friendly. If you use sterile soil, there is less need for synthetic chemicals. Therefore, you end up preventing soil and water pollution.

Remember, synthetic pesticides and fertilizers contain toxic chemicals that can endanger human and aquatic life. So, if you want to conserve your environment, always use sterile soil.

Is it necessary to sterilize new potting soil?

It is essential to note that most potting soils in your local garden store have undergone sterilization as a gardener. So, there is often no need for sterilizing potting soil unless you plan to reuse it.

Garden soil, on the other hand, is usually in need of sterilization. You can sterilize garden soil using either chemical or heat treatments. Regardless of the method you choose, ensure you analyze your requirements. If you have large amounts of soil, consider solarization.

Safety cautions to observe during sterilization

When you sterilize garden soil, you have to exercise certain precautions. Note that you should avoid exposing the soil to temperatures higher than 180 degrees Fahrenheit. Also, avoid leaving the soil in the heat for very long periods.

Doing this facilitates the production of toxic chemicals in the soil. Some of the poisonous substances likely to get released when this happens are soluble salts and ammonium compounds. These toxic compounds can prevent germination and lead to growth abnormalities in plants.

Why do soil sterilization?

Sterilizing gardening soil is essential for healthy plant growth. At present, there are various techniques you can use to sterilize garden soil.

Some include solarization, exposing soil in an oven/microwave, and steaming soil. All these methods are effective; hence, your requirements will determine your best option.