Unfortunately, it has probably happened to every recreational gardener on occasion that mold is discovered on and in the potting soil on freshly potted plants after just a few days. You can use a wooden stick to reliably check whether the white clouds actually belong to the genus of fungal spores or are just dissolved minerals from the irrigation water. If the deposits are solid and fine-grained, it is lime that simply needs to be removed.
Why is my potting soil moldy and what can I do about it?
If potting soil is moldy, it may be due to too much moisture or poor quality soil. Infected plants should be taken outdoors, cleaned of mold and repotted in new, high-quality soil to prevent further damage.
Soft, light-colored hairs would be a sure sign that mold is beginning to form, which after a very short time will affect the entire pot ball. However, the mold spores are not entirely harmless to human he alth. No cosmetic treatment will help here, the plants now have to go outside as quickly as possible.
First aid for plants with mold spores
First, carefully take the infected pots outside, empty them completely and remove the remaining soil from the roots (with vinyl gloves!). If the infestation is severe, the root balls can be rinsed with lukewarm water before your houseplants can be moved back into new, high-quality potting soil and thoroughly cleaned pots. In principle, there are only two possible reasons for the beginning of rot in the planters:
- You meant too well with the watering, so that mold could form in the permanently humid environment or:
- It was poor quality soil with too much black peat or compost, which is usually more likely than a bag of potting soil that may have been stored for too long, which also tends to rot.
In the case of cheap soil (usually with an even cheaper composition), it also loses its biological balance due to its poor ventilation and tends to form mold as soon as its airtight foil packaging is opened. So purchasing branded soil would probably have prevented the rot that was going on?
Good soil, bad soil?
That was the title of a very representative potting soil comparison published in 2014 by Stiftung Warentest, which then immediately came to the conclusion that the differences in quality between the individual varieties are enormous. Soils with and without peat were evaluated, both from private labels from well-known DIY and garden centers (e.g. Kölle, Dehner, Toom, and Obi), as well as branded goods (from Compo, Floragard and Neundorff). Of the 19 products (price per 20 kg between just under 1.50 to 10.00 euros), one variety achieved a “Very Good”, five were “Satisfactory”, two were “Adequate”, one variety (just under 6, 00 euros) even poor, the rest “good”.
Twelve months later: light vs. heavy Earth
Potting soil with a high proportion of peat and coconut means less hauling and initially sounds good due to the high proportion of renewable raw materials (between 70 to 100 percent). Nevertheless, a year later, this time the testers from “Ökotest” reported that the light potting soils were not convincing either. The comparison in shorthand:
- 9 different soils tested, including from the range of Toom, Obi, Gartenkrone, Floragard and Compo;
- Price per 20 liters between 2.65 and 8.54 euros;
- Test result: 3 times “Satisfactory”, 4 times “Sufficient”, 2 times “Poor”
Alternatives to potting soil?
Surely you have already guessed that your own compost is the ideal means of improving the soil but also for the natural cultivation of all kinds of plants. Ökotest and BUND even strongly recommend that you generally avoid using peat as a component of potting soil. The arguments for this are actually understandable and not just because peat-free gardening protects our climate. In order to understand everything a little better, you can download a very informative leaflet for free from the BUND portal.
