Preventing Mold While Growing Cannabis

by Cedric JacksonJanuary 18, 2018

New and even seasoned growers can face mold issues on their recently harvested cannabis. In this article, we’ll explain the three main types of cannabis mold and how to prevent them. You've likely spent many months and lots of money, so it's important to have the most successful and healthiest plants possible.

One important thing to keep in mind is that mold can actually occur at any point of the growing stages, so it's critical to periodically check for it.

"Bud Rot"

Bud Rot occurs most often from the following issues:

Lack of air circulation

  • There has to be moving air in your grow space at all times. Keep a fan running pulling air out of your tent or other growing space.

Low temperatures

  • When temperatures in your grow are too low, mold has a tendency of forming.
  • Temperatures of 68°F/20°C or higher are recommended.

High humidity

  • Higher humidity means higher moisture in the air.
  • Keep a humidity monitor to make sure it stays low during your grow as well as harvest.

If you notice dark areas in your buds, it is likely bud rot. Bud rot looks different the further it progresses. So, when it’s new, it’s a white, fluffy mold. Dark purple or dark gray/brown spots are noticed as it progresses. Advanced bud rot leaves a speckled dust on your buds that can be blown away, but this doesn’t remove the mold so you still have to trim off the entire bud.

Curing bud rot involves taking the entire bud off of the stem. You’ll also have to remove any buds in close proximity to the rotted ones.

White Fuzzy Mold

White, fuzzy mold is regular mold. It's the most common form and you're most likely to find it on the leaves of the plant. It resembles an insect web and can spread with air circulation. Prevention is rather simple – make sure the climate of your grow is appropriate.

This means that your humidity level should be 20% at the absolute most but should hover around the 15% mark. Unfortunately, when you spot mold, it means that you’ll need to harvest your cannabis plant and those in the same grow space as quickly as possible – even if it isn’t quite done growing yet.

Powdery Mildew-Like Mold

If you’re able to catch this type of mold quickly, you can save your cannabis plant and the rest of your crop. It’ll look like flour’s been dusted over the leaves of your cannabis plant. It spreads like wildfire when left to breed, so once you first notice this, you need to take immediate action!

This mold eats the plant in order to produce more white powdery mildew. Keep your humidity levels low. Purchase a dehumidifier if you live in a naturally humid environment. Keep your airflow low until you’ve completely rectified the situation. Good ventilation and airflow help prevent mold.

Whenever possible, try to make sure the leaves of your cannabis plants aren’t touching much. The more the leaves overlap, the more moisture develops between them, which increases your risk for mildew-like mold.

What to do with Moldy Cannabis

Throw it away! You cannot smoke or cook with moldy cannabis. Not only could you end up becoming very ill, you could give yourself a long-term medical condition. Don’t confuse mold for trichomes and crystals though – when your buds are fuzzy from those it’s a good thing!

Closing Thoughts

If you don’t notice mold growing on your cannabis plants until you’ve tried some of your harvest, don’t panic. Just toss the rest of the harvest and start over. Yes, it’s a big loss but it's better than risking yours and others' health. The key to mold prevention is to keep your grow’s climate tightly monitored and airflow plentiful.

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