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Heat Stress

Heat Stress

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When cannabis plants are exposed to excessive heat and light, they can suffer from stress, which manifests as various symptoms on the leaves. Signs of stress include yellow or brown spotting, burned areas, leaf curling (either up or down), folding inward resembling cones or tacos, and serrated leaf edges flipping up. Additionally, high temperatures and low humidity can lead to dry, crispy leaves.

Cause of Issue
◉ Intense Light Exposure: Placing the grow lights too close to the cannabis plants can cause light stress, resulting in burnt and damaged leaves. ◉ Heatwaves: Excessive heat, especially during a heatwave, can lead to heat stress. This can occur both indoors and outdoors, affecting the plants' overall health and leaf condition. ◉ Insufficient Watering: Inadequate water supply during hot and dry weather conditions can exacerbate heat stress and contribute to leaf damage. ◉ Low Humidity: Very low humidity levels can make plants more susceptible to heat stress, even if the temperature is not extremely high. Dry, hot air can cause leaf edges to tip up and worsen symptoms resembling heat stress.
Symptoms
◉ Yellow or brown spotting on leaves near light sources ◉ Burned areas and crispy leaves ◉ Leaf curling (up or down) and folding inward like cones or tacos ◉ Serrated leaf edges flipping up ◉ Shrivel and wilting of leaves ◉ Growth of new buds on top of old ones (fox-tailing) ◉ Extended growth on top of buds (spires)
Corrective Actions
◉ Temperature Monitoring: Use temperature monitoring devices to keep track of the temperature in the grow room or outdoor environment. ◉ Heat Control: Employ methods to lower the temperature, such as increasing air circulation, using fans, and ensuring proper ventilation. ◉ Adjust Light Distance: If heat stress is caused by grow lights, move them further away from the plants to reduce heat intensity. ◉ Cool Roots: Protect the roots from heat by using insulation methods or providing shade to the root area. ◉ Seaweed Kelp Extract: Apply organic liquid seaweed kelp extract as a fertilizer to aid in plant recovery from heat stress and potentially protect against future episodes. ◉ Shade and Watering: Shield the plants from excessive sunlight by using temporary covers or shade sails. Water the plants in the evening or early morning to prevent water evaporation during the hottest hours. ◉ Move Potted Plants: If possible, relocate potted plants to shaded areas during heatwaves. Care for Heat-Stressed Plants: Give extra attention and care to plants experiencing heat stress, offering shade and ensuring they receive adequate water. ◉ Remember, prevention is crucial when growing cannabis outdoors, as it may take time for plants to recover from hot or dry spells.
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