How to sterilize cotton gauze at home

How soil can be sterilized in the oven

By Laura Graichen | January 08, 2020, 12:09 pm

Trillions of bacteria, organisms and insects live in soil and compost. However, viruses and fungal spores often mix with the microorganisms that can cause problems for plants. If you want to put young plants in self-made potting soil, you should sterilize the soil beforehand - in the oven.

Young plants have tender roots and are easy targets for fungi and mold spores. In addition, if they are exposed to too many nutrients, their roots can burn quickly. If you want to plant young plants in self-made potting soil, it is therefore advisable to sterilize the soil or the compost beforehand. You can easily do this yourself at home if you have an oven. “You can do that with potting soil. It should naturally be very low in nutrients and contain no weed seeds or anything else, because otherwise these would compete with the young plants, ”explains Sandra von Rekowski from the Bundesverband Deutscher Gartenfreunde e. V. upon request from myHOMEBOOK.

Sterilize soil in the oven - that's how it works

If you want to make your own potting soil from garden soil or compost, all you need in addition to the soil is an oven and some fine sand. Then proceed as follows:

  1. First, slightly moisten the soil.
  2. Spread flat on a baking sheet or other heat-resistant container.
  3. Heat at 120 degrees Celsius with top / bottom heat for 30 minutes. Stir in between, if there is a thick layer of soil, so that everything heats up evenly.
  4. Allow to cool well before use.
  5. Then mix the soil in a ratio of 1: 2 with fine sand and insert the young plant.

Note: If there are small white spots on the ground after sterilization, there is no need to worry. These are insect larvae or worms that have been killed by the heat. This is also not harmful, because even in a compost heap, temperatures of up to 80 degrees Celsius sometimes prevail, at which microorganisms die.

Also interesting: For these reasons, you should garden with soil without peat

Alternatively, sterilize soil in the microwave?

The principle also works in the microwave. To do this, set the highest level for ten minutes. Here, too, you should stir in between so that all layers heat up evenly. Von Rekowkski recommends using the oven instead. Too many nutrients could be lost in the microwave compared to the oven.

Do you always have to pre-treat soil?

There is no harm in sterilizing the earth, but it is not always necessary. To find out whether your soil is contaminated with harmful spores or germs, you can do the cress test.

  1. Fill a pot with some of the soil that will later serve as potting soil.
  2. Moisten the soil slightly.
  3. Then sow the cress.
  4. Then put the pot in a light and warm place and wait.

If the cress germinates, roots well and looks healthy within about three days, the soil does not need to be sterilized in order to use it as potting soil. The germ load is then low and does not harm young plants. If, on the other hand, the cress does not sprout, this is a clear sign that the soil contains too many germs, fungi or spores.

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