Very few hobby gardeners have probably thought about this. In spring you get potting soil from the gardening store and sow flowers or vegetables in bowls on the windowsill. You only notice that something is wrong when pests start to spread. This wouldn't have happened with disinfected soil.
How to disinfect potting soil?
To disinfect potting soil, moisten unfertilized soil, spread it on an oven-safe plate or tray and heat it in the microwave (highest setting) for 5-10 minutes or in a preheated oven at 200 degrees for 20 minutes. Then let the soil cool down before using it.
Why do you sterilize potting soil or growing soil?
When growing new flowers or young vegetable plants, you usually sow in good potting soil. You fill small pots or bowls and place them on the windowsill or in a heated greenhouse to pre-germinate. After a while the seeds should open and small germs become visible. Often nothing happens instead, except for a brisk growth of mold or countless fungus gnats flying around the apartment. Occasionally growing young plants come to light, but cannot continue to grow if larvae eat their small roots.
The good growing soil was contaminated with mold spores or larvae of fungus gnats.
It helps here to add your growing soil sterilize or use expensive, purified potting soil (€6.00 at Amazon) from the specialist store. This is the only way the seeds can sprout optimally and grow into strong young plants.
Sterilize potting soil
Take old potting soil from last year or soil from the supermarket. Sterilization kills any pests or mold spores that may be present in any potting soil. Sterilization is done with heat, either in the oven or in the microwave. Proceed as follows:
- Take sufficient quantities of unfertilized soil.
- Choose an oven-safe or microwave-safe container, preferably a tray or plate.
- Moisten the soil well with water, but it should not drip.
- Put the soil flat on the tray or plate.
- Place the plate in the microwave on high for 5 to 10 minutes.
- Or preheat the oven to 200 degrees and put the tray in for about 20 minutes.
- Let the soil cool down thoroughly before using it again.
White worms or larvae may appear on the soil after sterilization. They became visible through the heat treatment. This isn't a big deal because the pests have been killed. The soil can be used.
