Tip leaves curling up. What could it be?

Leaf curling in plants can indeed be caused by heat stress, but it can also result from several other factors. Leaves may curl upwards or inwards to reduce their surface area and minimize water loss. Ensure adequate ventilation and cooling in your growing area. If possible, lower the ambient temperature to the ideal range for your specific plants (usually around 70-85°F or 20-30°C for cannabis). Adding fans or using air conditioning can help manage heat. Overwatered plants might have leaves that curl downwards and feel soft, while underwatered plants’ leaves may curl upwards and feel dry or crispy. Adjust your watering schedule. Ensure the soil has good drainage and only water when the top inch of soil is dry to the touch. Nutrient deficiencies or toxicities can cause leaves to curl. Common culprits include nitrogen toxicity, potassium deficiency, and calcium/magnesium imbalances. Leaf curling can also be a sign of pest infestations (e.g., spider mites, aphids) or diseases (e.g., fungal infections). Leaves might curl if the plants are too close to high-intensity lights, causing light burn. Some strains are more prone to leaf curling due to their genetic makeup.