Rid Your Indoor Garden Or Greenhouse Of Fungus And Mold

How to prevent and treat unwanted fungus and mold growth in your indoor garden and/or greenhouses.


Fungus and mold (a commonly found fungus) are primitive plants. So primitive they don't even produce chlorophyll, the substance that gives higher plants their green color. Fungus reproduces through tiny, microscopic spores, of which many kinds are present in the air at all times. In the proper hot or cold humid environment, these spores will take hold and begin growing. Fungus can infect your garden in two different ways: above the soil line(foliar fungus) and below the soil line (soil born fungus). Although the best method of fungus control is prevention, there are some instances in which fungus can get out of control and needs to be treated with a good organic or maybe chemical fungicide, if the case warrants its usage.


On your indoor garden and greenhouse plants there are two ways fungus can infest your plants: through the foliage and in the soil.

Leaf and stem fungus attack the foliage of a plant. They will appear as dark spots or splotches on a plants foliage. These forms of fungus are usually caused by using cold water(it is best to use tepid water for your plants) when misting plants, causing temperature stress or can be caused by excessive humidity (over 60%). The spots could develop into a fungus.

Prevention of these types of fungus is easy. Use tepid water, have a hygrometer (sold at most retail nurseries) to measure excess humidity, and most important, employ a vent fan to remove a majority of the moisture (all described further, later).

In case you still get foliage fungus you should remove any infected foliage and leaves first. Then spray with a fungicide (Captan and Maneb work well but use your best judgement, there are better brands coming out all the time)3-4 times at 3-5 day intervals. As long as the preventative measures are taken there should be no real outbreak of fungus.

Soil born fungus attacks the root system of a plant. It is usually seen on the surface of the soil first, and then growing around the roots in the soil. Soil born fungus is mainly caused by the usage of an unsterile planting medium and/or improper drainage. Poor drainage will keep your roots too wet, making them vulnerable to fungus and root rot. To prevent soil born fungus, a sterile planting medium and good drainage are essential. Good drainage is easily attained by having adequate drainage holes(any store bought container with holes in the bottom) and the proper soil texture. There are plenty of good potting soils that have excellent drainage texture(in indoor gardening experimentation is your only real guide as far as the materials you buy are concerned).

If fungus becomes a problem even after your preventative measures you can treat with Captan, Maneb(both easily attained at retail nurseries), or a biodegradable soap solution to the soil. Three to four applications are usually necessary. Mix the fungicide according to the directions and apply, making sure the soil is not over watered and there is adequate drainage. Again the problems should clear up as long as proper preventative measures are taken after the fungicides are applied.


Prevention is the main ingredient in fungus control, in your indoor garden or greenhouse. First, you should remove anything that might promote or harbor fungus and mold, such as clothing and curtains. If your indoor garden has carpet make sure it's covered in plastic or remove the carpet completely. Then check the humidity of your growroom, with a hygrometer, to make sure it isn't too high.

A good growroom is kept at about 50% humidity, and between 70-80 degrees Fahrenheit. If your growrooms humidity and temperature are too high, installing a squirrel cage fan, attached to a hygrometer/thermometer(easily purchased at a garden center or retail nursery), to ventilate the room will usually clear up your problem. If your temperature and humidity are low you can buy a heater and attach it to the thermometer and for low humidity attach a humidifier to the hygrometer. With proper maintenance and preventative measures you should have no more problems with unwanted fungus or mold growth in your indoor garden or greenhouse again.

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