Eliminating And Preventing Mold In Greenhouse

Eliminating And Preventing Mold In Greenhouse

The best approach to shield your plants from the various threats of the natural world, such as fluctuating temperatures and light levels, as well as unwelcome pests, is to cultivate them in a properly-constructed greenhouse. Mold is one example of the maintenance issues you may encounter. In this article, let's learn some tips on eliminating and preventing mold in greenhouse, the proper way!

Mold thrives in warm, damp conditions. However, mold spore pollution and the transfer of spores among greenhouse plants are both manageable. Black sooty mold, powdery mildew, and gray mold are the three most frequent forms of plant-growing mold.

What Are Molds?

Molds are microorganisms that thrive in warm, humid conditions. The majority are minute yet common and proliferate swiftly by spreading spores into the air. They will begin to establish new colonies after settling on a surface, which will then release more spores, and the cycle will continue.

Mold exposure, which can happen by inhaling the spores it emits, is typically harmless. Still, it's not a problem you want to take, especially in those with weakened immune systems.

People allergic to fungus may generally have symptoms similar to allergic responses, such as nasal congestion, a runny nose, and an itchy throat. In the worst-case scenario, symptoms may include fever, exhaustion, and fungal infection. Don't be alarmed; these occurrences are uncommon, and any effects you observe will most likely dissipate after the mold has been removed.

Mold will, of course, harm the plants in a greenhouse. Fungi, unlike plants, cannot undergo photosynthesis. Thus they must obtain nutrition from other sources.

Some molds receive their sustenance from wood and decaying leaves. The more invasive types feed on live creatures, and the little breathing openings in plants called stomata are roughly equivalent to a wide-open front door. The minuscule spores readily enter the body, and the parasitism starts.

Regardless of the numerous types of mold and their behavioral patterns, prevention and eradication are generally identical across the globe.

Three Types Of Molds


Botrytis cinerea Black Molds  Powdery mildew
Botrytis cinerea black molds White mold


Three types of mold infect greenhouse plants.

  • Botrytis cinerea- the most prevalent, this ash grey fungus grows on leaves and tiny fruits, taking nutrients from the plant cells it destroys via poisonous secretions. Never underestimate the spreading of grey mold. Remove a plant with grey mold from the conservatory quickly if you notice a plant with grey mold.
  • Sooty mold- a mold that appears like black soot on plants. Mold development is typically induced by ecological factors such as excessive humidity or certain temperature that allow molds to flourish. These are widespread in citrus trees, such as limes and lemons. 
  • Powdery mildew- Which appears to be a white or greyish powder, may also be a major problem in a greenhouse. Powdery mildew is a prevalent problem in greenhouses. However, it does relatively little harm, despite its unpleasant appearance, with its dusty, white foliage and blossoms.

How Do You Get Rid Of Molds?

Fill a spray bottle with at least 3% hydrogen peroxide and apply it to the afflicted region. After around 15 minutes, properly wipe off the surface and clean it as you normally would.

Another alternative is vinegar. Spray the area with vinegar using a spray bottle. After approximately an hour, wipe it down and rinse it with water.

To be safe, use either hydrogen peroxide or vinegar first, followed by baking soda, which will remove the moisture that molds feed on. Next, spray the moldy area with a small amount of baking soda dissolved in water in a spray bottle. Finally, cleanse and dry the affected area.

Hydrogen peroxide, vinegar, and baking soda are all safe for plants. Therefore, they are the preferred alternatives. Even if you don't detect mold development after removing contaminated plants or parts of the plants, it's to your greatest advantage to using one of these procedures in the area where the plant was.

However, if you are not very careful, the mold may subsequently appear elsewhere because some spores floated off before you removed it. As a result, you'll most likely have to repeat this step.

Getting Rid of Gray and White Mold

After being infected with gray or white mold, the plants will be unable to recover. Therefore, remove the sick plants from your greenhouse with care. The important aspect is to keep the spores or sclerotia from spreading whenever you move them. After removing the plants, burn or bury them.

Powdery mildew removal

Powdery mildew on plants is far less dangerous. Because it does not directly harm the plants, leaving them alone is an option; nevertheless, it is advisable to pluck off the changing leaves, as they may obstruct sunlight or spread to other plants.

Getting Rid of Black Sooty Mold

It's a different scenario when it comes to removing black sooty mold. Unlike other varieties of mold, black sooty mold is generated by sap-feeding insects such as leafhoppers. The mold is the result of these bugs depositing honeydew. So, to cure your plants of mildew, you must first get rid of the insects.

Ants will also guard sap-sucking bugs since the bugs offer honeydew for the ants to eat. This mildew takes an entire web of insect collaboration to form on your plants. Place ant lures around plants with the sooty mold first, then use insecticidal soaps or lotions to control the sap-sucking bugs.

How To Prevent Mold In Greenhouses?

The best strategy for preventing mold in your greenhouse is prevention. It makes no difference how thoroughly you remove existing mold if the circumstances that permitted it to form in the first place are not changed.

There are a few major preventative strategies. These measures are vital to follow regardless of whether you have a mold problem. If you've had a mold problem, improving one or several areas will provide a long-term solution.

It all boils down to water, ventilation, and cleaning to keep mold at bay in your greenhouse. If you complete these three essentials correctly, your greenhouse will have a far higher chance of being mold-free.


Keep and maintain the right temp inside your greenhouse

Greenhouse mold thrives in warm temperatures. However, if you position your greenhouse to the south, it will receive direct sunshine first thing in the morning. It will aid in the speedy drying of the morning dew.

Although it helps to decrease mold formation due to moisture buildups, this trapped heat will produce a humid and most atmosphere if not promptly ventilated. Therefore, the humidity and temperature levels must be balanced. Begin by purchasing a greenhouse thermometer and hygrometer to track the daily temperature and humidity levels. 

Control the humidity levels

The most important aspect of maintaining your greenhouse mold-free is minimizing water collection, both on plants and on the building's surfaces, and preventing excessive humidity.

Mold is more likely to grow when the humidity level is above 85%. Keep in mind what you're growing, but I'd recommend aiming for a humidity level of 30%-50%. By boosting ventilation and avoiding overloading your plants, you may minimize humidity.

Also, avoid over-watering your plants. If there is too much for the plants to drink, the mold will gladly help.

Wipe out the greenhouse surfaces where moisture accumulates regularly using a rag or sponge, and pay attention to check for moisture on the flooring. Finally, if you notice any leaks, ensure they are adequately addressed and any water-damaged areas.

Proper ventilation

Mold cannot develop without enough air movement. When ventilation is restricted, humidity levels rise, allowing spores to propagate. In addition, the wind and circulation generate a natural airflow.

On the other hand, a fan may be used to boost ventilation in a greenhouse. Install it in the greenhouse's front or rear to pull warm air through the greenhouse and then blast it outdoors.

Allow enough space between plants.

Spores can spread by air, water, and direct contact. As a result, maintaining plants a few inches apart and avoiding allowing the leaves of different plants to become entangled will help with mold avoidance. This also benefits the plants since it promotes airflow, sun exposure, and a faster drying period after watering.

Thin plants in phases, keeping in mind the mature size of a growing plant. Plant leaves and stems can be thinned by removing or snipping them off. Spacing plants 2-4 inches apart is recommended depending on what you're growing.


Keep your greenhouse clean

Nothing can't be fixed with some good old-fashioned hygiene. Clean your greenhouse's floors, ceilings, and surfaces as much as the material allows. If you want to go the additional mile, cleaning surfaces with hydrogen peroxide or vinegar can't harm you.


You have a significantly improved understanding of how to keep mold from growing in your greenhouse now. In addition, you are aware of what to do if mold has already begun to grow in your greenhouse. Always remember that maintaining proper water levels, ensuring enough ventilation, and performing thorough cleanings are the keys to success.