The many causes of leaf curling

Plant leaves curl in response to various environmental stressors. When certain pests, such as psyllids, mealybugs, and thrips, feed on a leaf it can cause leaf curling and deformation. When plants are too hot or too dry, they can also curl along the entire leaf margin. Some diseases, usually viral, also cause leaf curling. So, when you see leaves of your plants curling how do you know the cause? Below are some general guidelines:

• Leaf margins curling down, no yellowing – underwatering
• Leaf margins curling down, yellowing – overwatering
• Leaf margins curling upwards – heat or wind stress
• Leaf curling mainly in new growth and in deformed ways – often a disease or insect pest
• Middle or old leaves curling and have patchy yellowing but green veins – Magnesium deficiency
• New leaves curling and have patchy yellowing but green veins – Manganese deficiency