You already have much You put effort and time into growing your first plants and just when you thought everything looked perfect, you notice mold? What is the cause and how can you avoid mold on potting soil in the future?
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You don’t have to change much to prevent mold from growing in your nursery pots.
Avoid mold on growing soil: the climate matters!
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Why is my potting soil moldy?
Ideal conditions are necessary for mold to form and grow. These are basically the same as our beloved edible mushrooms: warmth and humidity.
These site conditions are especially true if you have “built” a mini greenhouse, for example if you cover the pots with a hood. The humidity then quickly builds up, which, in combination with a higher temperature, promotes the formation of mold.
Act quickly to save the plants
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If you don’t change something quickly, the whole thing will result in the seeds or young plants also becoming moldy, making them unusable. What can you do if you notice mold on the potting soil? Can you still save the plants?
First try the less radical variant:
If mold is only found here and there, you can remove the affected areas or the upper layer of soil. Add a new layer on top of the old one. Once you have identified the cause of the mold formation (e.g. incorrect care), change it (you can read below how to avoid mold on growing soil in the future). Observe whether mold forms again. Photo: Perova Evgeniya/Shutterstock
If the potting soil becomes moldy again, proceed as follows:
The moldy potting soil or growing soil must be disposed of. The plants are also removed for this purpose. Whether they survive depends, of course, on how big they are. Plants that have not yet developed a sufficiently strong root system are likely to die. Also rinse the soil from the roots. Disinfect the pot thoroughly or use a new one. Fill it with new potting soil, the old one is definitely useless. Plant the plant carefully and water. Drain the water really well. If it is too wet, you risk mold again.
How you can successfully avoid mold on growing soil in the future
Of course, you never want to go through that annoying, extra work of mold removal again. But what should you take into account?
Obtain high-quality soil for growing
There is special potting soil and this is the only right one. You can also mix some yourself. Don’t skimp on quality. Only use soil that has been stored indoors. Moisture due to the weather can penetrate the packaging, so you should quickly equip yourself with growing soil that may already contain mold spores. Any soil is first disinfected. This works best in the oven (at 120 degrees for 45 minutes). Pots, whether old or new, are also disinfected with hot water and vinegar.
The right temperature
It is a decisive factor. It has to be warm enough for the seeds to germinate, but not too warm to avoid the warm, humid climate. The optimal growing temperature is between 17 and 23 degrees (also consider the location such as a window and/or heating nearby). If it is a little cooler, this is usually not a problem, as many plant species germinate at lower temperatures. It’s always best to find out more about the type of plant you choose before cultivating it. Photo: Perova Evgeniya/Shutterstock
Be careful when watering.
Only the area around the seeds needs to be moist at the beginning. So it is not necessary to soak the entire soil. Instead, it is best to use a spray bottle and only moisten the top layer of soil (approx. 2 to 3 cm). As soon as the roots have grown, watering can be carried out more generously. However, it should never be soaking wet. Drainage is the best way to avoid accidental overwatering and subsequent mold on potting soil.
Hood, or not?
Make sure the humidity is between 50 and 70 percent. In general, covering the pots is an advantage for cultivation. The seeds permanently receive the necessary moisture and the plants also benefit from it later, because the soil does not dry out so quickly. What you should not forget, however, is that the moisture that will collect in the air under the hood due to the irrigation water does not accumulate. To do this, you must remove and ventilate them once a day. Add holes to the hood through which air can circulate outside of ventilation times. This is especially important when the humidity is too high.
You can read about what you can currently prefer here.
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