Does Rain Lower The Potency Of Cannabis?

How Rain Reduces the Potency of Cannabis & Ways To Protect the Buds

Rain is one of the weather hazards that keep outdoor cannabis growers up at night. 


When it pours down heavily, you wonder if the rain will wash away all the juicy resin glands and reduce the potency of your buds.


In this article, we’ll explore the effects of rain on cannabis buds and how you can mitigate the problems, if any.


Does Rain Lower The Potency Of Cannabis? 

The rain can lower the potency of cannabis but not in the manner that most people think. Hard-pounding, stormy rain can knock off the trichomes on the top colas, leaving them less concentrated of essential cannabinoids. Still, the rain affects your buds in more than one way. 


Trichomes are particularly vulnerable to physical pounding. So when the rain rages on for hours, the trichomes on the top colas can get knocked off pretty easily.


As a result, you lose most of the ripe trichomes when the plant doesn’t have enough time to replace them. 


Thus you harvest buds that have fewer trichomes than they normally should, reducing their potency.

Does Rain Lower The Potency Of Cannabis?
Trichomes contain the essential cannabinoids, if knocked off, the resulting buds will be less potent


Most people think that the loss of potency is due to the rainwater diluting the trichomes. 


Nothing can be farther from the truth.


Trichomes aren’t water-soluble, so if it rains mildly and the trichomes aren’t knocked off the flowers, the rain won’t affect them.


The resin glands are most vulnerable in the last stages of flowering. 


Once you have spotted those clear trichomes burgeoning, they should be protected from a furious downpour.


The bigger they get, the riskier because their surface area broadens, thus more exposure to the raindrops.


The rain can also cost you an entire harvest if you don’t attend to your plants after a heavy downpour.


The water trapped within the buds creates a highly humid environment that encourages the growth of mold. 


So, in essence, a heavy downpour will not only knock the ripe trichomes off the plant but also makes the buds more prone to mold.


Thus, with a heavy downpour, the buds might become less potent, and your harvest can also reduce considerably if the mold problem isn’t contained. 


Why The Rainy, Overcast Days Are Troublesome To Cannabis Plants

Though the rain is a resource to outdoor plants, it can affect your plant’s development adversely.


During vegging, it is much harmless. The plant is still growing the frames and bud sites upon which the flowers will bloom.


However, during flowering, the rainwater gets logged into the flowers, causing mold and mildew.


Long rains and cool weather are the biggest scare. 


Other than the hard-pounding rain knocking the trichomes off the flowers, cool, rainy days promote mold and fungi. 

Mold can spread pretty fast. If you see mold on the leaves, inside the buds could be worse.


These can spoil your entire harvest in a matter of hours.


Once the mold begins in the heart of the buds, your big buds will turn to gray molds. And in the rainy weather, it spreads so fast you might not save your plant in time. 


Also, buds grow fatter and thicker when the sunshine is intense. Rainy, overcast days limit the bud’s access to sunlight. Thus inhibiting the buds’ development. 


Even if the rain doesn’t last for long, the overcast days that follow the rainy days leave moisture on the buds for long. 


When the sun shines, moisture evaporates faster, which reduces the risk of bud rot. 


Overcast days are particularly troublesome because the air tends to be more condensed, inhibiting airflow. If your plants are not trimmed well, mold is more likely to attack them. Lastly, when the rain pours down excessively, nutrients can leach from the plants, starving them. If the plants get waterlogged, your plants are likely to suffer root rot.


How Do You Protect Your Marijuana Plants From Rain?

You can protect your marijuana plants from the rain by spraying them with pH-adjusted water, shaking them after rains, or bringing them indoors when it rains. There are more ways to protect the buds. Let’s explore further. 


The buds are vulnerable to the rains. If the trichomes aren’t getting knocked off, the rainy days make mold and mildew almost an unfortunate guarantee.


Here are ways to protect the buds from the rain;


Spray The Buds With PH Adjusted Water

The buds take in a lot of water that stays in them for long. This makes the environment moist and acidic, conditions that favor fungal infections.


Mold cannot attack buds in alkaline conditions. So spraying the buds with water adjusted to pH 8 neutralizes the acidic environment and keeps the mold at bay.


The easiest way to increase the PH is to use pH Up, but you can also use sodium bicarbonate. 


The application of potassium bicarbonate on the buds alters the pH of the water in the buds. The change in pH helps kill the fungal spores and reduces your plants’ susceptibility to mold and mildew. 


The buds will be safe as long as the PH-adjusted water stays on the buds. 


Mold can only occur when incessant rains wash the PH-adjusted water.


You should thus ensure you repeat the process after another heavy downpour.


Shake The Plants After The Rain

After the rains, the buds and the leaves hold a lot of water. Shaking the buds removes most of it. 


Whatever moisture is left after you shake the plants can naturally be evaporated, even when the sun shines mildly.


Shaking the buds only might not help if you’re growing in highly humid climates. You can combine the two— shake the plant, then spray them with pH-adjusted water if the weather forecast doesn’t favor them. 

This plant has been shaken after rain. The water on the flowers will evaporate faster, evading mold


Watch The Plants 

Inspect the flowers after a heavy downpour for signs of mold. Overcast days limit sunlight and slow the rate of evaporation. This promotes the spread of mold.


If spotted early, fungal infections can be controlled. But fighting bud rot when it’s already advanced is futile.


And when you look for the mold, explore the core of the buds. The thick top colas are the worst because rainwater lodges in deeper. 


If you spot the mold earlier, on the outside, deep inside the clusters is where you want to focus. Most times, you think you’ve dealt with the mold only for the hidden spores to wreak havoc.


Harvest As Soon As You Spot A Case Of Botrytis

If you’ve spotted a few cases of bud rot, harvest the plants as soon as possible. Botrytis spreads so fast, and once it attacks, you should remove the healthy buds before they get infected too.


Removing the buds earlier will not allow them the last weeks of maturity, but you get something. Once the trichomes are milky white, they can be harvested.


So don’t let botrytis spoil everything as you wait for them to turn amber.If it’s too early, simply cut the affected buds and contain the spread by spraying the pH-adjusted water on the remaining buds.


Grow Mold-Resistant Strains

If you’re growing in an area that receives long rains, it makes sense to begin on the right footing.


Investing in mold-resistant strains makes the most sense because your plants are likely to be swathed in highly humid conditions for long.


This sounds easy but can be pretty difficult because most breeders are concerned with potency and yield. 


But when you get it right, your plants will be hardier to the vagaries of weather. 


Note: Do not cover your plants during the long rainy days because covering the plants restricts airflow. Restricted airflow and high ambient humidity make the buds even more susceptible to mold. 


Is It Ok To Leave Marijuana Plants Out In The Rain?

Leaving the plant outside in the rain isn’t okay when you can move it indoors. The rains can damage the trichomes by beating hard on them and making them more prone to mold infections.


Thus, moving the plants inside during the rainy days saves them from mold and mildew if you grow outside in a pot. However, if you’re growing in the ground, you will only have to tend to the plant after the rain. 


Can Rain Damage Trichomes?

The rain can damage your trichomes, especially in the last stages of flowering when the bulbous trichomes are big. The rain can physically damage them or will promote fungal infections, which are worse. 


In conclusion, rains, storms, and heavy winds are problems outdoor cannabis growers grapple with. Rain is especially worrying when it beats down hard for hours during the last stages of flowering. I hope you found the tips in this article helpful.


Keep growing!



  1. Ed Rosenthal’s Marijuana Growing Tips