Cannabis plants are known to be hardy plants that grow wild in many parts of the world. Across the different regions, these plants have evolved naturally to thrive in a wide range of environmental and geographical differences in temperatures, humidity, etc. Just like many other plants, cannabis plants have different stressors, including heat or, in this case, too much heat. In this article, we will get to understand more about cannabis heat stress and the different ways to avoid and cure this problem.
Cannabis Heat Stress
Cannabis plants need to be at a temperature of between 70 to 75 degrees Fahrenheit during its period of light to thrive best. During their period of darkness, on the other hand, temperatures should be maintained somewhere between 50 to 60 degrees Fahrenheit. When temperatures get too high, your cannabis plants may start to exhibit signs of stress on their leaves. As we all know, heat and warmth is a necessary component for any healthy organism, including cannabis plants. Unfortunately, too much of it can cause adverse reactions, like stunted growth and the loss of quality yields.
It is important to know the symptoms of heat stress on your cannabis plants to prevent and remediate the problem. The buds closest to the light source of your grow room will often exhibit the first signs. Aside from a generally dry and withered look, the following are signs that your heat levels are too much for your plants:
- Tips of the leaves look burnt, bleached, and stretched
- The appearance of yellow and brown spots, primarily around the edges of the fan leaves
- Leaves start to curl up or down or fold inward like tacos
Cannabis heat stress is much more damaging once your plants reach their bloom stage. During this phase, your plants will focus on growing buds and fewer leaves. That means there will be lesser leaves to block the light or heat source and your buds will turn up airy and loose. New buds can start to grow out of the tops of the older ones. This is what is known as a foxtail. When these happen, yields will be reduced significantly.
In certain states, like California, Texas, New Mexico, and Arizona, heat stress may be a common challenge for cannabis growers. These arid places usually have little rainfall and low humidity. While some varieties may be able to tolerate the heat, certain strains will not do so well with the high temperatures.
Tips to Prevent and Overcome Cannabis Heat Stress
Monitor and install the necessary equipment.
This step is crucial in any heat management system to track not only the temperature in your grow room, but the humidity level as well. Invest in thermometers and place them all over the space. Temperatures are never consistent across so ensure that you have these devices strategically placed at the canopy levels, ground levels, and in spaces in between.
If your grow room is situated in an area where it will be quite challenging to cool, like terraces and balconies with concrete walls, consider buying electric coolers or using air conditioning. This is one advantage that indoor growers have over outdoor cultivators. Make sure to also install an exhaust system with carbon scrubbers to vent out heat from the room. Fans are also a cheap and simple solution to disrupt hot air and help cool things down. Fans in a poorly ventilated area, however, are not a good idea as they tend to increase heat due to motor friction.
Adjust the light source.
Since your light source is always the main culprit for cannabis heat stress, make sure that they are at an ideal level from your plants. Sometimes a small adjustment is all it takes to bring the temperature levels down around your plants. You can always move your lights up and away from the plants, or, if you are running out of space, you can always train your plants to grow outward. Hold your hand at plant height under the light source; if the heat is uncomfortable, then most likely, your plants will feel the same.
Modern technology has given us air-cooled lights that are equipped with reflectors to lower the amount of heat emitted from the lights. If however, you are using standard grow lights, make sure to keep them at least three feet away from the top of your plants.
Do not forget about the roots.
Keeping the root system of your crops cool is an important part of heat management. Even if the symptoms show up in the leaves, the problem could very well start in the roots. Planting your cannabis plants in sunken beds is one way to keep the root system cool by giving small amounts of shade during part of the day, also helping to maintain moisture levels. In this type of environment, any ambient moisture will easily run down onto the plants in the trenches. This is especially helpful as higher temperatures require more water to prevent the soil from drying.
If you are planting your cannabis in containers of sorts in an outdoor environment, make sure to use light-colored ones to reflect light instead of absorbing it. Be extra cautious when it comes to potted plants as they can easily overheat. You can simply move the plants to a better location out of direct sunlight.
Use supplements.
Once the environment is cooled down using the techniques mentioned above, you can use supplements to remedy some of the effects of cannabis heat stress. You can try using seaweed kelp extracts to assist in the recovery process. These extracts have been proven to be beneficial not only in treating heat-stressed plants, but they are also used to avoid future stress from getting your plants. They are loaded with lots of trace elements and minerals that help make plants more resistant to high temperatures.
Cannabis heat stress is most common for indoor plants. It can damage an entire crop if left unchecked. However, they can easily be prevented and remedied using the steps outlined above.
