How to Control Greenhouse Humidity During the Hottest Months
Summer is here, and is the prime season for greenhouse cannabis growers: the plants are thriving, the buds are growing quickly, and everyone’s focused on the harvest just a few months away in October.
Now, perhaps more than any other time of the year, maintaining optimal conditions in your greenhouse is salient - - which means keeping a close eye on the humidity and heat levels.
However, with the temperature fluctuating so much between the hot, bright days and the cold, dark nights, it can be difficult to maintain the proper levels of humidity and heat.
So, let’s take a look at the factors that contribute to the high humidity levels during the hot summer months, as well as how you can make sure your greenhouse maintains optimal levels throughout the scorching season.
Why Summer Changes Greenhouse Humidity
If you’ve ever felt incredibly uncomfortable on the hot, sticky days of summer, then you know exactly just how much humidity levels can rise during the hottest months. Your plants are likely also feeling that pressure as well and can hinder, or even completely halt, their growth and productivity.
The higher temperatures can cause your cannabis plants to perspire, much like humans do. The water that beads to the surface of the plants will then evaporate, increasing the level of humidity in the greenhouse. Which, considering hot air already holds more humidity than cold air does, can raise the humidity levels to dangerous (for the plants) conditions.
But, that doesn’t mean humidity is totally cannabis’ enemy. In fact, maintaining high humidity levels can prevent your plants from overheating in a process called “dampening down.” During this process, the high temperatures are regulated by the introduction of water into the greenhouse. The water absorbs the heat within the room before it evaporates and leaves the greenhouse.
That being said, too much humidity can wreak havoc on your plants by creating perfect conditions for mold, fungi, and botrytis (also called “Bud Rot”) -- among plenty of other bacteria and diseases -- to thrive. Let your humidity levels get too high in the greenhouse, and you may end up cultivating moldy bud.
Raising Cannabis Greenhouse Humidity in the Summer
Just as evidenced by the “dampening down” process, higher humidity can levels can actually protect your cannabis plants from stress and other adverse effects caused by heat. That’s why it behooves growers -- especially those who live in dry, hot regions -- to actively try and maintain humidity levels at a slightly higher level than the outside air.
You can do this by:
Introduce more moisture by spraying water directly onto the flat surfaces of the greenhouse in the early morning. The water will evaporate throughout the day, raising humidity levels slightly, safely, and slowly.
Install a spray or drip irrigation system to continuously deliver moisture in the most efficient way possible, whenever it’s needed. This system can be connected to your automated environmental controls, so you don’t have to worry about doing it manually.
Install a shade covering on your greenhouse, or utilize a solar diffusing polycarbonate covering on the greenhouse ceilings and walls as a way to direct the harsh sunlight away from the greenhouse and slow down the evaporation process.
Reducing Humidity Levels in the Summer
Reducing humidity is generally far more of a challenge for greenhouse growers than increasing it. This is especially true on those super hot, super humid days where it’s sticky and muggy with too much moisture in air that is already high enough for mold to grow.
There are a few things you can do to mitigate the increasing humidity levels and maintain the proper moisture level for your cannabis plants:
Water your plants early on the day, so their leaves and buds have time to fully dry off before the cold night arrives
Ensure adequate air circulation throughout your greenhouse to push the warm, moisture-laden air away from the cannabis and out of the greenhouse.
Keep the ground in your greenhouse thoroughly weeded. Apart from being invasive, weeds hold moisture and perspire, releasing more moisture back into the air.
Double-check the drainage of your greenhouse floor, making sure water doesn’t start to pool because then it will evaporate and add to the increasing humidity levels.
Install a steep roof pitch (or anti-drip polycarbonate) to prevent condensation from building up and dripping down onto the plants below.
Controlling Cannabis Greenhouse Humidity
There are numerous benefits to growing cannabis in a greenhouse, versus outside in the open air -- chiefly, far more efficient humidity, temperature, light, and environmental controls -- that allow you to keep your cannabis grow thriving all year-long, rather than just throughout the summer.
Unfortunately, for those who aren’t super familiar with the conditions in a greenhouses versus the conditions outdoors, controlling greenhouse humidity -- especially during summer -- can be a serious challenge.
However, by keeping a close eye on your greenhouse humidity and heat levels, you can protect your cannabis plants, grow your yield, and keep your greenhouse healthy and thriving all the way through harvest.
Follow me on Instagram for more cannabis content!