Despite loving care, a whitish coating suddenly appeared on the soil in the flower pot. Mold is not uncommon in indoor plants. Targeted action is required to eliminate the danger quickly. If the potting soil is moldy, you should try these 7 methods.
mold in the potting soil
identify mold
First of all, it must be clarified whether the whitish coating on the potting soil is actually mold. This phenomenon can generally have two different reasons. For one thing, plaque can be the result of water that is too hard. On the other hand, it is possible that the potting soil becomes moldy. If the water used to water the plants is too hard, limestone will form on the surface of the substrate over time. As a rule, the separated lime has a slightly yellowish tint and a crumbly or hard consistency. The mold covering, on the other hand, looks rather fluffy and soft.
Risk of mold growth
Although mold causes discomfort in connection with one's own home, in nature it plays an important role in the cycle of the ecosystem as it feeds on dead organisms. They are found in almost all soils and contribute to the formation of humus there. There they pose no danger to plants, humans or animals. They only become a health risk - especially for sensitive and allergic people - when they release spores.
conditions for growth
The ideal breeding grounds for mold include organic materials such as humus or compost. If enough moisture is added, the fungus will begin to grow. In order for the mold to be able to spread at all, the following criteria are necessary:
- excess moisture (wet substrate or over 60% relative humidity)
- organic substrate
- depending on the type of mushroom, temperatures from 0 to 50 degrees
- low oxygen content in the substrate
- pH values between 4.5 and 6.5
Even sterile soil cannot be kept free of mold spores in the long term. As a rule, however, the fungus does not bother us because it does its work underground. If the conditions are optimal, however, it can suddenly spread and the potting soil becomes mouldy.
By the way: clay soils or other substrates with a high mineral content are less susceptible to mold growth.
methods of combat
If the substrate surface molds, this is a sign that the fungus is forming spores to multiply. This fungus lawn should be removed quickly in any case. It is best to bring plants whose soil is moldy outside first. So the spores cannot spread uncontrollably in the room. For sensitive people it is advisable to wear gloves and a breathing mask.
Combat with sand
In order to get rid of the mold lawn on the potting soil, it is necessary to make the conditions as uncomfortable as possible for the fungus. The most common reason for the soil becoming moldy is overly well-intentioned watering behavior. If there are many mold spores in the substrate, even brief waterlogging can cause its surface to become mouldy. Therefore, let the bale dry well first. Be sure to remove the top layer of soil, although the mycelium is likely to be found further down. Then cover the surface with a layer of mineral components about two centimeters thick.
The following are suitable for this:
- sand
- expanded clay
- pumice
- lava granules
expanded clay
The large surface area of these materials allows the potting soil to dry out more quickly. In addition, they do not provide the mold with a suitable food source. This method is particularly suitable for plants that are in a large bucket on the balcony or terrace.
Repot indoor plants
In most cases it is not necessary to replace the entire potting soil at once. However, repotting can never hurt. If you provide the plant with fresh, high-quality potting soil that is well permeable to air and water, you will not only remove the mold, but also prevent mold from forming again. Get the root ball out of the pot in a well-ventilated place on the balcony or terrace and remove as much of the old substrate as possible. If a lot of it still sticks to the fine roots, the soil can be rinsed off with water at room temperature. For planting, you should preferably use high-quality soil with a proportion of sand. If you put the plant back in the same pot, it must be cleaned and sterilized. You can kill the fungal spores in different ways:
- boiling water
- hot vinegar solution
- Alcohol (at least 70%)
Combat with home remedies
In addition to the purely mechanical removal of the mold, it can also be combated with various agents in the potting soil. In the case of houseplants, however, the chemical club is not recommended. There are some home remedies that help in the fight against the substrate fungus and do not pollute the environment. The funds are primarily preventive, but are still effective to a limited extent when the soil is already visibly moldy.
liverwort extract
Liverwort extract is a natural product that quickly degrades in the soil without leaving any residue. In general, mosses have an antifungal effect. This effect is particularly pronounced in the three-lobed whipmoss (Bazzania trilobata). It protects against a variety of fungi and other pathogens and at the same time strengthens the plants without being toxic to humans and animals.
- preventive: 5 ml extract in 1 l water
- Spray every 10 to 14 days
- acute: 20 ml liverwort extract in 100 ml water
- spray three days in a row
By the way: It is also possible to use peat moss.
tea tree oil
Tea tree oil is a natural all-rounder. It not only helps against sucking insects on plants, but also has a good effect against mold. As a rule, a mixture of 15 to 20 ml of tea tree oil in one liter of water is sufficient to kill the mold spores on the plant soil. To do this, simply spray the solution onto the affected soil surface and, if necessary, repeat the procedure a few days later.
Tip: Alternatively, you can also place cloths soaked with the mixture on the potting soil for about two days.
activated charcoal
If only a very small part of the substrate surface is covered with a fluffy white fungal covering, activated carbon can prevent further spread. To do this, sprinkle the powder finely on the potting soil and repeat the procedure after a few days.
cinammon
As an alternative to activated charcoal, sprinkling cinnamon on the surface of the soil can kill the spores to some extent.
Sterilize potting soil
If the potting soil has already become moldy in the bag, you do not necessarily have to throw it away. Smaller quantities can easily be sterilized. The germ-free soil is perfect for sowing flowers and vegetables. Since the mushrooms do not tolerate temperatures well above 60 degrees, they can be rendered harmless with a heat treatment. However, this process also kills all other microorganisms and animals that are in the substrate. There are two simple ways to do this:
1. Microwave sterilization
Dampen the potting soil with water so that it is slightly damp. Then fill a flat layer in a microwave-safe container.
- 5 to 10 minutes
- highest step
2. Oven
Alternatively, you can sterilize the substrate in the oven.
- preheat to 200 degrees
- Cover the tray with moist soil
- treat for at least 20 minutes