Powdery Mildew In Grow Tent

(Last Updated On: September 18, 2021)

White is not always the symbol of peace. Take white powdery mildew as an example. These fungi take the plants as a host to reproduce and rob all the plant’s nutrients to eat and breed.

It germinates within 2 hours under favorable dry and humid conditions, and the infections are visible after 2 days. Within this short period, you must take effective action to stop the outbreak.

Powdery Mildew In Grow Tent is one of the most frequent fungi attacks you’ll face in the grow tent. So, having a fundamental knowledge of powdery mildew will keep you ahead of time.

This article includes all the needed details, and you’ll find the solution you need to apply according to your plant’s condition.

What is Powdery Mildew in Grow Tent plants?

What is Powdery Mildew in Grow Tent plants

Powdery mildew is a fungal infection or disease of the plants caused by different fungi species. The only host for these fungi is the plants. They need to adapt to the living cell host to reproduce while infecting and harming the host in several other ways.

How to Identify Powdery Mildew on Plants?

How to Identify Powdery Mildew on Plants

Unlike other fungi invasion, identifying powdery mildew in plants is relatively more straightforward and pretty distinctive. The initial symbols are visible white spots on the top portion of the leaves, also sometimes stems.

An inexperienced grower can mistake the powdery white spots for dust and try to wipe them off. For the record, visibly these powdery spots eventually come off after wiping, but in reality, it still exists and keeps making the plants more vulnerable.

Most likely, you can locate powdery mildew on the leaves near the ground or at the corner of the grow room. At first, the size of the mold is pretty much like a coin or a watch battery. If the size is bigger than that, it means it already has been a few days since powdery mildew had attacked the plants.

It starts with the ground leaves, and the fungal spores quickly spread the disease to the above and around. As the fungus continues reproducing, you may notice the leaves drying out and facing discoloration.

Another particular area other than leaves that are severely harmed by the white powdery mildew is young foliage. Anyway, keeping an eye on these commonly affected areas will let you identify powdery mildew on plants in the earlier stage.

How Does Powdery Mildew Harm the Plants?

How Does Powdery Mildew Harm the Plants

According to some, powdery mildew doesn’t destroy the grow space entirely, however, others say that it nearly causes the crops to lose a harvest.

And so here I will tell you the real truth. This parasite spreads rapidly from one plant to another while sucking up its nutrients to increase its genesis. It harms the host acutely to the point of death by the lack of nutrition.

If not, the deficiency of strength in plants to fight back against other pests or diseases also results in premature death.

Additionally, it causes the plants to go through-

  • Limited yield because of sickening plants
  • The stomata’s photosynthesis ability reduces significantly.
  • Mess up or ruin the flavor of affected fruits or vegetables
  • Quickly becomes prey to other insects and diseases
  • The leaves dry out fast and turned out to be fragile
  • Plants harshly suffer from sunburn and overheating

Starting from the roots, it swiftly moves to the top of the plants and harms the buds.

So you ought to be extra careful because even if you manage to get rid of the fungus before the harvest, the plants still fail to recover, and consequently, you are left with a poor harvest.

How Does Powdery Mildew Spread So Fast And What Is The Solution?

How Does Powdery Mildew Spread So Fast And What Is The Solution

The life cycle of these fungi starts with spores, then germinates and reproduces actively. Now the spores can enter your grow room with your hair, body parts, or clothing. The scary thing is you are not the only potential carrier of this fungus.

It can be transferred into the grow space via insects, pets, or anyone who occasionally comes to visit your grow space.

On top of that, this mildew is airborne, so you never know if it first came through the vent with the air. Killing the whole genesis by applying the fungicide or other methods doesn’t work much on the air, so this particular problem asks for a specific solution.

The solution- Ozone Generator

Ozone restricts the movements of mildew spores in the air. It produces unlimited ozone gas and cleans the air around it. This is how it ends the lifecycle of mildew spores and prevents it from causing an outbreak.

You might have heard about this device before, as it also comes in handy in getting rid of odors and smells in grow tents. Continuing that, Ozone Generator can be a quick pick to solve the problem instantly.

Why Does Powdery Mildew Invade the plants?

Why Does Powdery Mildew Invade the plants

It is almost time to ask yourself, why are these parasites invading your grow space? Well you see, there isn’t much difference in the answers to what I have already given you in the section why a grow tent gets infestation. The reasons are pretty common and repeated.

But the gardening habits and particular conditions that attract the powdery mildew most into your grow area could be any of these discussed below-

Excessive Humidity

An overly humid atmosphere is so far the most welcoming reason behind the powdery mildew infestation in your grow space. High humidity is the best place for them to thrive and spread.

This fungus germinates comfortably at a temperature around 72-88 Fahrenheit (22-31C). This environment is highly suitable for breeding, so they grow in this damp area, starting at the lower portion of a plant where the crop is mostly shaded.

Insufficient sunlight

Sunlight is intolerable to numerous germs, parasites and the same goes for powdery mildew. The intense sun rays kill the spores before they can severely harm the stems or roots of the plants.

Evidently, insufficient sunlight encourages mildew breeding as lack of the sun rays creates a calmer atmosphere. That is why the sunlight deficiency could be a significant reason why the mildew spores don’t get killed; instead, they survive and thrive.

Congested Placement of Plants

Placing a higher number of plants than the area can reasonably accommodate initiates a lot of problems, and the presence of powdery mildew is one of them.

If your grow tent is overly crowded with different plants, naturally, the lower portion of the crops has less light intensity than the upper because of the bushes.

So that area where enough air is not being circulated or getting any light is an ideal space for powdery mildew to show up and spread without the grower’s knowledge.

Prone to Specific Seasons and Conditions

As we have already mentioned, any place with an average temperature and less light is favorable to these parasites. In late summer and autumn, when the daytime has moderate temperature and nights are dewy, these fungi get a tremendous response.

However, powdery mildew becomes an expected problem in grow rooms, greenhouses, or more extensive harvesting areas while dry seasons are at the door as these places are growing crops all year round. Only taking up some special care might get you lucky in this case.

Weak or Stressed Plants

If the plants are growing weak, already lacking nutrition, or maybe placed in a crowded corner where ventilation is not on the priority list, then those plants are most likely vulnerable or stressed.

In that case, these plants cannot fight back and easily fall prey to other pests, including powdery mildew.

How To Get Rid Of Powdery Mildew In Your Grow Room?

How To Get Rid Of Powdery Mildew In Your Grow Room

Well, that’s a tricky question. Because there are endless remedies, methods, and chemicals that will help you control the infestation. But you cannot end it entirely unless you tidy up the whole mess and start a new slate.

Of course, we do not suggest giving up on the crops if you have noticed the invasion of mildew in the early stage. Don’t just go around eradicating plants left to right.

Here we have listed many organic and chemical products that are amazingly effective in getting rid of powdery mildew in the shortest possible time.

Organic/Natural Solutions

If you have tracked out the powdery mildew infestation in the initial stage, go with the organic solutions.

Neem Oil

You might already know, neem oil is an essential key to remove different harmful species away from the plants. Also, neem oil is handy and available pretty much everywhere. It provides satisfactory results within 24 hours and if not, then at least in a couple of days.

Spraying neem oil on this fungus disturbs its respiratory system and kills it almost immediately. Do not spray it directly on the buds; it may tamper with the taste or flavor of the vegetables or fruits.

Alkaline Water

Alkaline water is a fruitful resolution if your plants are affected by powdery mildew in the late flower phase. The PH level of Alkaline water is 8.0+, and a higher PH level prominently decreases the mildew’s reproduction.

Apply alkaline water once or twice a week and stop applying while the buds are about to mature. There is a mixed opinion whether it causes bud rot or not, but it is better to be safe and discontinue applying at certain phases.

Apple Cider Vinegar

Another commonly used home remedy against pests is the apple cider vinegar mixture. It has acetic acid, which forces the parasites to leave the hosts.

The acid in this vinegar is problematic for the leaves; thus, a mixture of 2 tablespoons of organic apple cider vinegar with each quarter of freshwater is eventually better. Spraying this mixture every 3 days will hopefully put an end to the primary infestation.

Baking Soda/ Sodium Bicarbonate

Baking soda is a significant ingredient that kills a wide range of germs and fungi. Add 1- tablespoon of baking soda with ½ teaspoon of liquid soap (non-detergent) into 1-gallon water and spray the mixture on the plants.

Remember, baking soda might leave an alkaline residue that looks like powdery mildew at first sight. Do not worry; you can wash it off with plain water and determine if it was baking soda residue or white powdery fungi.

Non-Natural Solution


Fungicides can be chemical or biological compounds that kill the mildew parasites at first shot. A few fungicides suggestion directly from the expert growers are-

Food-grade Fungicide

If you are sensitive to using fungicides in your edible production, you should go for food-grade fungicides. These fungicides are made of pure ingredients that are edible and harmless to humans.

Sulfur Burners

Powdery mildew is vincible by sulfur in most of its life cycle. Sulfur has a toxic reaction to powdery mildew, which inhibits its cellular respiration system.

An average amount of sulfur in a primary infestation should be 100-200ml in every 100 litres of water. Run the sulfur burner 12 hours at first, and then 1-5 hours per night would be enough.

Stop applying sulfur before the buds start forming. Avoid spraying it directly to the buds unless you want sulfur taste in your fruits or vegetables.

Unpasteurized milk

Milk has been proven to eradicate powdery mildew if you combine it with 60% water whereas. The fresh milk portion should be 40%. But you must apply the fresh unpasteurized milk to achieve the best result.

Spray the mixture every 10 to 14 days to ensure a noticeable result.

Using tools

This method can only be effective if you notice the invasion on the first day while only a few leaves or portions are infected.

Here you need to cut off the infected area with a plant clipper or trimmer and then put the damaged part straight into a bag before proper disposal.

Many growers gradually look for the affected area while putting the previously cut portion on the ground. Then they wonder in a few days, from where have these mildew come back!

But in reality, the parasites never left. Spores were transferred into the ground and continued harming the plants as it is supposed to do. so if you cut the infected leaves, immediately get rid of them.

How To Cure White Powdery Mildew?

How To Cure White Powdery Mildew

Unfortunately, getting rid of the powdery mildew is not enough to regain the crops. While you are removing the mold, in the process, it has already injured a certain portion of your plants.

But if your plants are still in an earlier phase, treating the affected crops accurately might increase the yield. For this purpose, consider applying these few essentials that help the crops to recover their health.

  • Milk has been proved as a practical idea while it strikes in killing a parasite and boosting the host’s immunity. The compounds in milk work on point to remove powdery mildew as you spray it onto the plants after adding the needed amount of water.
  • Compost tea contains several anti-fungal properties that fight against mildew and, at the same time, serves as an organic fertilizer. Combine 1-portion of compost tea with 6-part water, let it soak for 7 days till the color of the tea is visible, and then use it diluting with water.
  • Silicic acid is formulated with amino acid & silanol, which creates a form of silicon. It initiates a delusion as the plants are on steroids, giving them a healthy platform to grow stronger and recover from any health issue.

How To Prevent White Powdery Mildew?

How To Prevent White Powdery Mildew

Grow areas, where the environment is primarily dry and highly humid, will always threaten the plants of powdery mildew. Also, mildew is pretty common even in a warm area and constantly attacks the plants, so your grow space isn’t safer either.

So what can you do? In these situations, you should always stay alert and apply precautions. But you might think, what is the benefit of prevention if the mildew is going to attack anyway?

Without a barrier, your plants will be infected at the first chance, and by taking necessary precautions, you are preventing the mildew infestation many times without even knowing it.

So, let’s go over a few major prevention options-

  • Control the humidity level and keep it under 70% RH altogether, whereas 50-55% during harvest and 45-50% while blooming.
  • As high humidity is a significant issue that causes mildew invasion, use a Dehumidifier additionally to limit the overly humid in the grow space.
  • Restrict unnecessary people, equipment, pets from entering your grow area to reduce the chance of carrying spores along with them.
  • Welcome new plants/clones inside the grow room only after disinfecting. For that, spraying organic or DIY mixture is enough for any sized plant. Zero Tolerance Fungicide is an effective product to use for this purpose.
  • Decrease the plant’s density and don’t put them near the wall or corner. If necessary, ensure extra ventilation to those areas, maybe an oscillator fan to reduce the humidity.
  • If you notice the existence of powdery mildew, stop running the fan and treat those plants first. Otherwise, the airflow might progress the spread of infection.
  • Hepa filters extract mildew spores from the air before it enters the room. It massively helps by keeping out the airborne pathogens.
  • Ozone generators kill the parasites in the air immediately and also neutralizes odor. This device is ideal prevention which has different advantages along with preventing mildew spores.
  • There is no alternative to cleanliness. Cleaning and maintaining hygiene can hold off pests, parasites including mildew.

How To Clean Grow Tents After Powdery Mildew?

How To Clean Grow Tents After Powdery Mildew

By squeaky cleaning the grow tent, we can finally say goodbye to the mildew permanently. As cleaning the tent is the only option left to prevent the white mildew infestation, make sure to clean the grow space after every harvest, once in 3-months or while suffering from invasion.

Follow the steps below to clean and restart your farming in grow tent:

1. Evacuate the grow tent

Start the cleaning process by evacuating the grow tent. Take out all the pots and plant containers, and the fans and filters, too, if possible. Leaving anything behind will give you no benefit of cleaning as the spores rapidly spread and increase their number.

2. Wash the room

After removing everything outside of the grow tent, prepare an effective mixture to wash and ensure that the solution kills the powdery mildew and disinfects the entire room.

Some of the common combinations are-

  • Bleach solution

The range of water and bleach are accordingly, 3:1. With this mixture, wipe off the surface and equipment, also might go for a pressure washer.

  • Hydrogen Peroxide

Apply 3% hydrogen peroxide added with water to hinder the growth of powdery mildew. Though this mixture cannot kill the spores, it is suggested to exert one day after the cleaning with bleach solution.

  • Hot soapy water

Warm water and liquid soap is another alternative that temporarily washes the rooms and tools. Use 3-portion of water with 1-portion of liquid soap to clean and make sure to rinse after cleaning.

3. Disinfect the floor

Sometimes you forget or give less importance to disinfecting the floor. But it is powdery mildew we are fighting; the ground might already have uncountable spores. If we aim to end it once and for all, we have to plan different strategies to clean the floors.

If your grow area has soil ground, use a carpet to cover the floor and vacuum the upper side or cover it with a weed barrier. As a result, the spores will be locked inside. You can work on other parts of the tent at that time and decide what to do with the soil.

You can either use an anti-fungal spray or better replace the soil with new and unused soil. Always go for organic mixture instead of pesticides while spraying and if the mildew invasion is on the point of no return, and then prefer changing the flooring soil.

4. Sterilize the filters, vents, and light holders if necessary

All the equipment inside your grow room has most likely come in contact with powdery mildew spores. That being the case, take all the equipment outside, mainly the intake vent, and sterilize it with isopropyl alcohol and then again put them to work into a mildew-free grow tent.

5. Keep humidity in check

Think again about why you are going through this hardship of cleaning your grow tent very often in the first place. Yes! Powdery mildew because of the high humidity level.

Do not repeat the same mistake. After cleaning the room, let it soak and be adequately ventilated for 48-72 hours. Add an oscillator fan or whatever you are already using for ventilation to complete the process nicely.

Before you start redecorating your grow tent with new soil and plants, do not raise the humidity level over 30% for 72 hours. After this period, place the plants and follow the humidity they require to thrive.

Frequently Asked Questions

  1. What temperature kills powdery mildew spores?

Temperature over 93 degrees and below 43 degrees kills them by hindering the development of powdery mildew spores.

  1. Can I remove powdery mildew permanently?

No. Removing powdery mildew is temporary if your grow area is prone to these parasites. By following proper prevention, you might reduce the chance of infestation and damage to the crops.

To Conclude

White powdery mildew in grow tents is a common phenomenon. So it might be best if you could regularly count on the preventive measures and closely inspect the crops to find out the invasion as early as possible.

Always stay on guard, be ready with whatever you need to challenge the powdery mildew because no one likes the concept of losing a harvest ever for this fungus.

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