meeldauw cannabis schimmel

How To Handle Mildew On Cannabis

If you’re into growing your own weed, or if you’re simply keen on gardening, you’ve probably heard of mildew. In fact, chances are you’ve seen it without even knowing you were looking at mildew. About time for a crash course in stopping mildew on cannabis plants then; this is a problem no grower wants to see on their weed!

Tips Against Mildew On Cannabis

Mildew grows like a white, powdery layer of dust on many plant species. Unfortunately, cannabis is no exception. No matter how picturesque mildew may look, it is quite lethal for your growing attempts. That’s why we’re giving you some tips to help you fight back as soon as you spot mildew on your cannabis plants.

What Is Mildew Anyway?

Mildew is a common fungus. In the case of weed plants, the fungal infection usually reveals itself on the leaves first. Initially, mildew looks a bit like blisters or pimples on the leaves. From there on, it gradually forms a white, powdery substance that will cover your entire plant eventually.

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Let’s get straight to the point: mildew is extremely bad news for cannabis. If you let the fungus run amok, it will destroy your entire harvest without a second thought. That means you’ll need to treat your entire grow pronto as soon as your detect mildew on even one of your plants.

Of course, mildew is just one of the many dangers that await on the path of any grower. As with just about all fungal infections, cross-contamination is a big issue here – one you want to avoid if possible! Many potential cannabis killers are able to spread through the air, and anywhere they land, a new disaster is waiting to happen.

As difficult as preventing mildew may seem, getting rid of an actual infection is decidedly harder. All the more reason to check these tips for dealing with mildew early on!

mold fungus mildew

How To Get Rid Of Mildew On Your Weed Plants

The process of stopping mildew from ruining your harvest consists of three deceptively simple steps:

  1. Learn how mildew spreads;
  2. Learn how to spot mildew in time;
  3. Solve the problem.

Below, we’ll highlight the essence of each individual step.

1.) How Mildew Spreads Across Your Cannabis

As the old adage goes, the best defence is offence. The same applies to mildew. ‘Know your enemy’ is another wisdom to keep in mind. Once you know the strengths and weaknesses of mildew, you’ll find it easier to arm yourself – and your plants – against this blight.

mildew on cannabis plants
It can be hard to tell where the trichomes end and where the mildew begins…

Essentially, mildew is at its most lethal when air humidity levels rise above 57%. The risk of catching mildew increases further in poorly ventilated (grow) rooms. Making sure your ventilation is in order is key to preventing mildew from catching on. While that implies outdoor growers have less to fear from mildew than their indoor counterparts, the fungus can also spoil plants in the open air. Out in your garden, pick a spot with plenty of air flow, and most importantly: keep checking for signs of early infection!

Mildew has a preference for attacking young plants first. These taste better to the organism, or at any rate, they’re easier to digest. One way of detecting mildew early, at least indoors, is noticing changes in how your young plants smell.

Once mildew starts to assume its full white powder form, it’s safe to conclude your affected plant is lost. Your main concern now becomes preventing mildew from spreading to other plants. Make sure your plants are sufficiently spaced out to make sure no leaves touch each other. While you’re setting up your grow, keep in mind that your plants will grow larger. Make sure you give them enough room in advance.

2.) Discovering Cannabis Mildew On Time

Thankfully, detecting a mildew infection is not that hard to do. Just make sure you keep a close eye on your young plants. Green leaves are a particularly conspicuous backdrop for spotting white anomalies.

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In the early stages of infection, you will notice small blisters forming on the leaf surface. The moment you detect this, it is time to act decisively. Even if you don’t see mildew, but spot other signs of fungi, you can safely assume that mildew is present, too.

A final point of attention is the colour and condition of your leaves. Healthy plants have dark green leaves. If you notice leaves that are slowly turning yellow or curling up at the tips, your plant may be at risk of dying.

3.) Solving Your Cannabis Mildew Problem

There are three effective ways to combat mildew. Interestingly, each technique is organic in nature and does not involve industrial fungicides. Two of these involve spraying; the third technique revolves around cleansing the infected leaves by hand.

The first spray technique uses a solution of 250ml water and two tablespoons of apple vinegar. Spray this mixture onto the leaves to remove the mildew, or to prevent untouched leaves from getting infected.

mildew cannabis spray

The second spray consists of a 60% water and 40% milk mixture. This solution is only used in outdoor sunlight grows or high intensity lighting setups indoors. An alternative option is using fish oil, but this is considerably more expensive.

The third technique involves taking a piece of damp kitchen towel and gently wiping the mildew off the infected leaves. If you decide to try this, be very careful to change your kitchen towel before switching to the next plant to prevent spreading the infection!


As mentioned above, mildew is capable of devastating your entire harvest if you’re not careful. Fortunately, you are not powerless when you have to deal with it yourself. Good preparation, a suitable grow room and plenty of space between your plants will cut back infection risks considerably. Another helpful choice could be picking strains with high resistance to fungi, such as Fatkid’s Cake, for instance.

fatkid's cake mildew
Fatkid’s Cake has some solid genetics…

On top of this, be very alert to any changes you spot in your precious plants. If you make sure you know what to do to tackle the problem, you stand a pretty food chance of killing mildew before it kills your grow.




fatkid's cake cannabis seedsFatkid's Cake

Fatkid’s Cake