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The Best Ways To Prevent Fungal Diseases On Your Plants

Fungal Diseases

Fungal diseases are one of the largest threats to indoor plant care. As anyone who has kept houseplants knows well, fungi are rampant in damp indoor environments. They thrive in the dark, moist conditions that so many indoor spaces provide. 

Fortunately, fungal diseases are fairly easy to prevent. And there are several steps you can take to ward off the worst effects of fungal attacks.

 In this article, we’ll discuss the most common forms of fungal disease and their prevention methods. Keep reading to learn how to protect your plants from fungal attacks.

Fungi: The Good, Bad, and Botanical Basics

Fungi are a part of nature. They play an important role in the health of ecosystems, and they are used by humans to produce essential medicines. Yet, fungi are also strict indoor plant parasites. They can spread disease when they’re present in indoor environments, and they can destroy both soil and plant life when they’re left unchecked.

Despite their bad reputation, fungi aren’t all bad. They’re essential to healthy ecosystems, after all. They’re also an important part of a gardener’s arsenal. You can use fungi to control certain pests. You can culture fungi to protect plants from disease. And you can use fungi to repel pests, prevent soil erosion, and stimulate plant growth.

Why is fungus harmful to plants?

Infections caused by fungi can range in severity, but most fungal diseases are accompanied by wilting plant foliage. At their worst, fungal diseases can kill indoor plants. In milder cases, chemicals used to treat fungal diseases can damage the foliage of sensitive plants, including orchids, African violets, Zygophyllum indoor plants, and many other common indoor plants.

Fungi can also cause infections in humans, resulting in skin conditions such as athlete’s foot. Some fungi even cause food poisoning in humans. Beyond the obvious danger to plants and humans, there are many other dangers associated with fungal infections. For example, certain plants, such as palms and ficus, are extremely sensitive to fungal infections.

What Are The Most Common Fungal Diseases?

In this section, we’ll discuss some of the most common fungal diseases indoor plants face. As we mentioned in the introduction, each kind of fungus targets different types of plants. If you know what types of plants your potted plants are exposed to, you can better protect them from fungal attacks.


Botrytis is a fungus that attacks flowers, foliage, and stems. It occurs when there’s too much moisture in your indoor environment, or when you have low humidity levels. It’s a major threat to outdoor plants, too. But outdoor plants are much more resistant to the disease.


Melanoma is another fungus that attacks plant stems. But it also causes leaf spots on indoor plants. Leaves with melanoma develop brown spots and blackness.

Powdery mildew

Powdery mildew is a fungal disease that causes grayish-white powdery white fungus to develop on leaves. It’s especially common in humid, warm indoor spaces.


Blackspot is a fungal disease that causes black spots to develop on leaves. It can also cause leaf drops.

Alternaria Leaf Spot

Alternaria leaf spot is a fungal disease that causes yellow-brown spots to develop on leaves.

Other Fungal Diseases

Other fungal diseases include black rot, bacterial infections, and spider mites.

How To Prevent Fungal Diseases On Your Plants

Now that you know the most common forms of fungal disease, you should be better prepared to combat them. In this section, we’ll discuss how to prevent fungal diseases in your indoor plants.

Protect Indoor Plants From Fungal Attacks 

The best way to prevent fungal diseases is to protect your indoor plants from fungal attacks in the first place. Maintain ideal air quality levels. Keep indoor spaces free of moisture and pests. Don’t overwater plants.

Keep Potted Plants Dry: 

It’s important to keep potted plants from becoming damp. But it’s even more important to keep them dry. When they’re not drenched with water, potted plants can’t become infected with fungi.

Prevent Soil Sitting: 

Soil sitting is the main cause of soil-borne fungal disease. Prevent soil sitting by keeping your watering schedule consistent and by watering only when the top 1/2″ of soil is dry.

Avoid Over-Watering

Over-watering is another common cause of fungal disease on indoor plants. Keep a watchful eye on your watering schedule. Don’t overwater. And if you notice that you’re watering your plants more than once each day, reduce your watering schedule.

Feed Fungi-Resistant Plants

Fungi-resistant plants are the best way to protect other plants from fungal attacks. Make sure you’re growing fungus-resistant plants.

How to Windows and Air Conditioning to Prevent Fungal Diseases

Climbing and orchids are particularly prone to fungal diseases when grown in warm, humid environments. In these plants, fungi thrive easily in conditions that are difficult for other types of plants. Eliminate any sources of excess moisture and high humidity in your houseplants’ growing area by ventilating your house and using an air conditioner. 

In addition, keep windows closed when it’s not sunny outside so that sunlight does not enter your house through windows that aren’t closed. When it’s hot outside, keep your air conditioner on to keep your indoor environment cool. If you keep your air conditioner turned off when it’s hot outside, you’re risking a buildup of moisture in your home that can lead to fungal diseases in your plants.

Make sure your humidity levels are ideal

What’s the ideal humidity level for your houseplants? You’ll want a level between 40 and 60 percent humidity, depending on the type of plant. Anything lower than 40 percent humidity and anything above 60 percent humidity can be harmful to sensitive indoor plants, including most orchids and African violets. 

These plants are very sensitive to changes in humidity, so keep your indoor environment as dry as possible and provide adequate airflow to prevent humidity buildup in your house. Another easy way to keep your humidity levels in check is to use a pebble tray. These trays are inexpensive and easy to use. Just place them in a spot where you don’t want to keep your plant too dry.

Removing Conditions That Lead To Fungal Attacks

Mild fungal diseases can be prevented with basic, everyday maintenance. For example, take care not to over-water your plants. This can lead to excess moisture that makes your plants more susceptible to fungal attacks. 

In addition, avoid letting dirt accumulate on the potting soil in your plants’ pots. Clean off your plant’s growing area with a disinfecting solution such as bleach once or twice a week. While you’re at it, wipe down your furniture and other surfaces that collect dirt and dust. Eliminate any insects or other pests that may be feeding on your plants.

In more severe fungal disease cases, you may need to use a fungicidal spray on your plants. A fungicidal spray is a liquid made of chemicals that kill fungi and fungi-infected plant tissue. Some types of sprays are made for outdoor use; be sure to use these when gardening outside. Bring any indoor plants inside during cold weather so that your houseplants do not get too much cold, wet weather.

Damping-Off of New Plants

If you’ve experienced fungal diseases in the past, you may want to take steps to prevent them from occurring again.

Plants that have been previously infected with fungi may become more susceptible to fungal attacks upon being planted for the first time. Therefore, it’s important to follow good plant-care practices during the planting and growing of new plants.

One easy way to avoid or prevent mild fungal infections in new plants is to damp off your new plants. This is a practice used by many commercial nurseries to protect newly planted seedlings from fungal infections.

It involves misting your plant with a weak solution of water, bleach, or fungicidal spray. This will kill any fungi that might be on your plant’s soil or on your fingers when you handle the soil.

What You Can Do To Protect Your Plants

If you’ve experienced fungal disease before in your houseplants, take extra precautions to protect new ones from infection. For example, grow plants that are less likely to be damaged by fungi, such as indoor plants that are less sensitive to cold. 

Another easy way to protect your plants is to keep cut flowers and other plants that require regular watering in pots rather than on the floor.

Another important way to protect your plants is to clean your plant-care equipment regularly, such as your spraying bottles, spritzers, and sprayer heads.

There are also special sprays and cleaners you can use to clean and disinfect your gardening equipment. And last but not least, be careful when watering your houseplants.


The best way to protect your indoor plants from fungal attacks is to maintain ideal air quality levels in your indoor spaces. Keep indoor spaces free of moisture and pests, and don’t overwater plants. Keep potted plants from becoming damp, and prevent soil from sitting. And last but not least, protect your potted plants from fungal attacks with fungicide-free plants.

Written by Chris Buckland

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