What Is The Best Way To Get Rid Of Powdery Mildew On Marijuana Plants?

powdery mildew marijuana

Growing marijuana can be one of the most rewarding hobbies a person can have. But it can also be the one of the most frustrating things that you can do too. It all depends on how your garden’s health is. At least that’s the case for me.

Growing marijuana is not as easy as a lot of people think. Many people think that it just ‘grows like a weed’ and all you have to do is plant a seed, supply water, and in no time at all the grower will be flush with dank nuggets. That’s not the case. World class marijuana takes a lot of skill and knowledge. Skill and knowledge comes with time, practice, and learning from failure.

Problems will arise in gardens. It’s not a matter of if, but a matter of when. Veteran growers will tell you that you have to take your lumps before you get glorious harvests. I always tell people that are starting to grow marijuana that the three biggest things to worry about beyond the basics of lighting and watering, is heat, bugs, and mildew.

I refer to those three things as ‘the three plagues’ that can ruin your garden in a hurry. For me, the hardest one to deal with is powdery mildew, and there isn’t a a close second. Bugs can be dealt with in various ways, and are easy to recognize. Heat can be handled with air conditioning. But powdery mildew is a pesky, microscopic menace that is very difficult to get rid of once your plants have it. And once your plants have it, it’s often too late.

Growers in the Pacific Northwest are very familiar with powdery mildew due to such a high level of humidity, a contributing factor to powdery mildew. Powdery mildew is a fungal disease in which root-like structures sink into the cells of a plant’s leaf structure. The structures spread across the plant, stealing nutrients from the plant and hindering growth.

Powdery mildew looks like someone dusted flour on leaves. It starts as a dot on a leaf or two, but if left unchecked, can spread to every inch of the cannabis plant. It will ruin harvests, and render the cannabis harmful to consume. It’s really, really nasty stuff. Since it’s microscopic, it doesn’t take much to spread.

So when you get powdery mildew, what do you do? If you are able to, throw the marijuana plant(s) out. Take a garbage bag and throw it over the entire plant and take it outside of the garden area for disposal. From there clean your room top to bottom and run an air purifier in there for as long as you can prior to putting new plants in there.

For most people, that option is unrealistic. In most cases, the person wants to try to salvage the harvest, and try to fix the problem without taking such extreme measures. I have seen some gardens that are able to shake the problem quickly because the issue was identified fast and dealt with immediately. I have also seen other gardens battle powdery mildew for months on end, to no avail, despite trying every trick in the book. People in those cases will tell you that they wish they could have gone back in time and just started over and saved so much struggle and headache.

If you find the powdery mildew quickly (a couple dots on a couple leafs), and the garden is in veg stage, it’s possible that you will be OK. But if it’s in flower, it’s best to scrap the harvest, as smoking powdery mildew is bad. There are certain conditions that people treat with medical marijuana that powdery mildew is very, very harmful to.

There are organic sprays that are sold at almost every reputable garden store that work well. If you look at the ingredients, it’s usually milks, baking soda, and some other herbs. I have also used ones that involve a lot of fish oil, which smells absolutely disgusting, and worked with mixed results. Below is a great homemade recipe that Ed Rosenthal recommends that I have used in the past with great results:

powdery mildew marijuana

The best way to deal with powdery mildew is to not get it in the first place if at all possible. Taking a proactive approach to preventing powdery mildew is something that every grower should do. Don’t wait until you get powdery mildew to deal with it. Know what causes it, and take measures ahead of time. Trust me, you will be glad that you did.

Poor air circulation, plant crowding, high humidity, poor lighting, and high temperatures all contribute to powdery mildew. Decaying plant material can contribute too. Keep your garden clean at all times. If leaves are dying, dispose of them. Leaving them in the soil, or on the ground in the grow room is bad news. Keep the air circulating, make sure that plants are spread apart and receiving excellent lighting coverage, and keep temperatures and humidity as normal and consistent as possible at all times.

An air purifier in your garden area is a must. Plants like clean air anyways, so even if you don’t live where powdery mildew is common, it’s still just a good thing to have around. I got a tinge of powdery mildew a couple of months ago, and I used the spray recipe in the picture above, and incorporated an air purifier, and haven’t had any problems since.

I do everything that I can to keep my garden area clean, and follow all of the recommendations above, and I still wouldn’t be surprised to see powdery mildew rear its ugly head again as my garden continues onward. Because of that, I make sure to keep all the ingredients to make spray at a moments notice. Powdery mildew can ruin your harvest, and your sanity, so do what you can to battle it before you get it.

Also realize that clones are particularly susceptible to powdery mildew. With clone availability spreading across legal states, more gardens are being infected as people bring clones home that seem fine, but are carrying mildew spores. If you are experiencing re-occurring powdering mildew problems with your genetics, you may want to start over from seed. If you are a newbie grower, or even a somewhat experienced grower that wants to learn more about cultivation, I suggest that you download my friend Robert Bergman’s free marijuana grow bible. He also offers a  support page that is a great tool. For more experienced growers, or those that are super serious about taking their cultivation to the highest level, I also suggest checking out Jorge Cervantes’ new cultivation book. If you have any tips and tricks for fighting/preventing powdery mildew, make sure to put them in the comments section so that others can benefit from your knowledge!

image via ILoveGrowingMarijuana.com

Johnny Green
About Johnny Green 662 Articles
Johnny Green is a cannabis activist from Oregon. Johnny has a bachelor's degree in public policy, and believes that the message should always be more important than the messenger. #LegalizeIt #FreeThePlant