What to do against heat stress in cannabis plants?

Your Cannabis plants may experience heat stress when exposed to too high temperatures. To save your Cannabis plants, you have to ensure adequate air circulation to your growing space. Make sure also to position your light accordingly that it receives appropriate lighting. Also, an exhaust system can control the heat of your growing area. It would be best if you also regulate your room temperature. Using ceramic pots can also help in cooling your Cannabis plants roots. Cultivating heat-resistant Cannabis plants can also help avoid the possibility of heat stress.

What to do against heat stress in cannabis plants?

What is cannabis heat stress?

Cannabis heat stress happens when Cannabis plants are cultivated in temperatures too high for them to handle. Cannabis plants, despite their toughness, require a specific temperature to flourish. When the temperature is inappropriate, cannabis plants begin to exhibit various physiological symptoms or signs of stress, which are not helpful in any form. Heat stress can affect both indoor and outdoor cannabis plants. It might harm plant health and reduce your overall harvest in the end.

What causes heat stress in cannabis plants?

Varieties of factors may cause heat stress in your Cannabis plants. The following are the known causes of heat stress in your Cannabis plants:

Low Humidity in your Growing Space

Increased transpiration is one-way Cannabis tries to counteract stress in high temperatures naturally. It implies that water must be present in the surroundings and root zone of the plant for it to transpire. Transpiration becomes much more difficult in low-humidity environments.

Exposure to Extensive Light

Anyone who has put their plant too close to the grow light may have seen a stop in growth. It is because heat stress is likely to happen when your grow lights are too close to your cannabis plants. If this happen, your Cannabis plants may have bleaching around the tip. They can only withstand a particular amount of light intensity before becoming overburdened. To avoid this, check with the manufacturer of your light for recommended hanging heights.

Poor Ventilation

Poor levels of grow room extraction are a typical cause of cannabis heat stress. The significant ways to have good ventilation are removing heat and maintaining a consistent supply of fresh air for photosynthesis and respiration. Check to see if your extraction fan is sufficient for your grow tent and, if not, you have to upgrade.

Growers in hot climates should keep an eye on the outside temperature. If the temperature outside of your growing space is 95° Fahrenheit (35° Celsius), you will never achieve low temperatures no matter how robust your extractor fan is. All it will do is blow in hot air and worsening the issue. Air conditioning is the best alternative in these conditions.


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What is the appropriate temperature for Cannabis plants?

To avoid heat stress in your Cannabis plants, you have to keep in mind the appropriate temperature of your growing space. During the day or lights on, keep the temperature between 75°-85° Fahrenheit (24°-29° Celsius). On the other hand, during dark cycles, regulate the temperature between 60°-75° Fahrenheit (16°-24° Celsius).


What are the symptoms of cannabis heat stress?

Mainly, cupped leaves, yellow or brown burnt spots, and foxtails are the common signs and symptoms of heat stress. Heat stress symptoms may vary in different stages, and the risk of heat stress varies with each growth stage. To understand better, the following are the heat stress symptoms in different growth cycles:

Heat Stress Symptoms in the Seedling Phase

  1. The seedling grows slowly.
  2. Newer leaves have a pale, withering appearance.
  3. Seedling development has been slowed. The seedling will die in extreme instances.

Heat Stress Symptoms in the Vegetative Stage

  1. The tips of your Cannabis plants may seem burned and curled. Bending leaves with soft leaf edges that appear dry.
  2. There are spots on the leaves that are maybe dried and brown.
  3. Browning eventually spreads throughout the plant if the heat stress issue is not resolved.

Heat Stress Symptoms in the Flowering Stage

  1. The leaves of the canopy may appear withered and yellowed.
  2. Instead of being flat, leaves may curl.
  3. Foxtail buds are long, airy buds that sprout from the top of other buds uniquely.

What to do against heat stress in cannabis plants?

Indoor Cannabis Plants

  1. Ensure that the room has adequate air circulation. Heat is generated by old led grow lights or non LED grow lights such as HPS, CFL, MH or CMH , which can lead to heat stress. For this purpose, you need to have at least one oscillating fan in your grow environment, adjusted to blow a light wind onto the plants. To keep the heat from the grow lights from harming the plants, you might have a fan blowing on top of the plant canopy.
  2. Check to determine whether the lights are positioned too close to your Cannabis plant. To see if the light is bearable, do a hand-test by keeping your hand towards the top of the canopy. If the lights are the source of the problem, reposition them.
  3. An exhaust system can control the heat of your growing space. Installing an exhaust system will aid in the removal of heated air from the area and the introduction of fresh air.
  4. Add air conditioning or coolers to the space to lower the temperature. Air conditioners decrease humidity, whereas coolers boost it.
  5. Keep an eye on the room temperature to ensure it’s suitable for Cannabis in both the vegetative and blooming stages. To assess what your plant is going through, hang your temperature sensor near the top of your plant canopy.

Outdoor Cannabis Plants

  1. Water your plants early in the morning or late in the evening if you happen to know the weather forecast to be a hot day. Remember, it is not a good idea to water the plant during the warmest part of the day.
  2. Your outdoor Cannabis plants work best from ceramic pots since they provide sun protection. It will aid in the cooling of the roots.
  3. Provide your outdoor Cannabis plants with some cover. If you choose permanent shade, avoid exposing your outdoor plants to the sun all at once since this might produce heat shock. Sheets can be a temporary solution but will decrease the amount of light your plants are receiving.
  4. If you had heat stress issues in the past, avoid future heat stress problems, by cultivate heat-resistant Cannabis strains.

What are some heat-resistant Cannabis strains?

There are several heat-resistant Cannabis strains that you can cultivate to avoid heat stress. These strains can better cope with hot and sunny areas. Keep in mind that even the most heat stress resistant strain can suffer from heat stress if the conditions are bad enough. The following are known heat-resistant Cannabis strains:

  1. Sour Diesel
  2. Blue Mystic
  3. Amnesia Haze
  4. Amnesia Mac Ganja (AMG)
  5. Fruit Spirit
  6. Afghan
  7. Aurora Indica
  8. Blackberry Kush
  9. Pineapple Express Auto
  10. THC Bomb Auto

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