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Cannabis Heat Stress

Cannabis heat stress

Cannabis heat stress is a real problem for growers and can happen pretty easily and to varying degrees.

Understanding cannabis heat stress

Cannabis heat stress is your plant’s cry for help before it dies from the high temperatures in your grow room. But this answer isn’t going to get you any points on the science exam. So, cannabis heat stress suggests that your cannabis plants are losing their capacity to self-regulate internal homeostasis – or “balance” – processes that aid in cooling. In other words, cannabis heat stress occurs when cannabis plants experience extreme temperatures above and below their tolerance levels.

Indications of heat stress on plants

Cannabis is a tough and resilient plant, with many earliest landrace cultivars tailored to survive in harsh environments like the Hindu Kush mountain range. Despite its adaptability, this plant species can only withstand a certain quantity of heat before its biological systems fail. Heat stress on cannabis plants in the flowering cannabis phase may not stress it in the vegetative stage; therefore, it is essential to comprehend what cannabis heat stress looks like so that you can ‘tuck it in the bud’ before it ‘does a handful’ on your plants.

Additionally, based on the phase and the cause of the heat stress cannabis plants, the signs of cannabis heat stress manifest differently. Heat stress cannabis symptoms primarily affect leaves near the top of the canopy and around the plant’s perimeter—areas in the line of fire.

Heat stress during the vegetative stage – If you notice the symptoms during the vegetative stage of cannabis, you can be sure that heat stress cannabis is to blame. Letting the tops of your plants grow too close to a strong light source could cause this in indoor grows. It could be the outcome of a fierce heatwave or a scorching and dry climate outside.

Heat stress during flowering stage – During the flowering period, heat stress on cannabis plants reveals diversely. New buds can sometimes start to flare up from the tops of older ones, much to the surprise of many producers. This can result in a cannabis plant heat stress foxtailing, a pillar of tiny buds and sugar leaves. Heat stress foxtailing is the second leading (and arguably more common) cause of stress in your cannabis plants. This is a plant-initiated survival mechanism in which the plant tries to form new buds competent in reproducing and generating seeds. This is the opposite of heat stress in buds.

Causes of cannabis heat stress

Heat stress cannabis could be to blame if your plants reveal indications of stress. Plants, like humans, can become irritated and stressed when they are exposed to excessive heat.

  1. Low humidity: Low moisture concentrations in the air make it difficult for plants to stay cool, causing them to become ‘thirsty’ and raise their temperatures. This can also result in cannabis moisture stress signs appearing.
  2. Nutrient burn: Surplus minerals can interfere with a cannabis plant’s ability to control its temperature.
  3. Excessive heat: Excessive heat is frequently caused by intense lighting. Light stress is also possible, as evidenced by leaf bleaching.
  4. Inadequate ventilation: Plants that do not get enough fresh air are at risk of overheating. Temperatures are reduced when air is replenished.
  5. Equipment failing: Growing cannabis indoors plants depend heavily on equipment. To avoid failure, you must check air conditioning units regularly.

Cannabis heat stress indoors

Growing cannabis indoors necessitates installing effective equipment to maintain a stable temperature. The effective tips to cool your grow room are configuring appropriate exhausts and air conditioning. You eliminate heated air from around the plants by enhancing circulation, allowing it to vent out successfully as fresh air enters the space. HID lighting, which generates a lot of heat, is common among indoor growers. Although this is advantageous in colder climates, HID lights can still trigger bud plant heat stress issues if positioned too close to crops. Indoor heat stress can be avoided or alleviated by enhancing your grow space.

  1. Use LEDs as they create almost no heat. Heat stressed buds bleach is most frequent with LEDs. This occurs in heat stressed over ripe buds, making them begin to turn white at the top.
  2. Place fans in your space. Fans will interrupt still, hot air and essentially make a convection current, which will aid in cooling.
  3. Install air conditioning to maintain cool air movement in your grow.
  4. Modifying the lighting position. If your plants start to show indications of heat stress, think about how close they are to light. If only the top fan leaves are exhibiting symptoms, reposition your lights to hang further away.
  5. Keep the temperature in the grow space or room below 25°C.

Cannabis heat stress outdoors

Controlling cannabis heat stress may be more difficult if you are growing outdoors, but you can still do a lot to assist your plants along the way. Outdoor cannabis plants may experience long periods of direct sunlight. This results in extreme heat waves that can last for days. Whatever your zone and weather, you should plan ahead to ensure that plants are prepared for prolonged periods of heat. Below are a few recommendations for protecting your outdoor crop.

Heat stress cannabis outdoors
  1. During a heatwave, water your cannabis plants in the early morning or evening when the temperature is lower. Water drops can intensify sunlight, directing more heat toward plant cells.
  2. It is preferable to grow cannabis in large containers or cannabis growing pots rather than on the earth. This makes your plants compact and allows you to physically relocate them to a sheltered location if the sun becomes too stressful.
  3. Use supplements to treat damaged cannabis heat stress plants. Nutritional kelp extract supplements help roots by controlling temperature and humidity. This lowers the risk of plants drying out if they overheat. They are high in nutrients and minerals, which help plants withstand high temperatures.
  4. Retaining your plants under a shelter all day will inhibit photosynthesis and harm the overall health of your plants. Conversely, making a temporary shelter out of cloth or tarpaulin can help shield your crop during the hottest part of the day.
  5. Select heat resistant strains – Some genetics tolerate heat much better than others, so verify to observe if your seeds have been bred to grow in hot climates.

Heat stress on cannabis plants is easily avoided if the basic growing standards are fulfilled. Setting up the proper space before you begin can save you a lot of headaches later on, so spend some time discovering the ideal environment for your cannabis plants. If you are concerned about your grow area becoming too hot, plan ahead of time, and you will be fine.

Picture of Ed Rushford

Ed Rushford

Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. About this Author

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