I'm new to this but what i have read about curling up leaves is below, and it is from autoflowringcannabis.com, but I believe it is the same for photo.
Overwatering
If you are giving your cannabis plant too much water, or too frequently, you might be overwatering them. Excess moisture and heat can cause your pot plant’s leaves to curl up.
Autoflowering cannabis plants use their roots to absorb oxygen. By drowning them in water, you prevent them from being able to access pockets of oxygen in the water. Continuous overwatering can also lead to your cannabis plant being waterlogged over time.
Solution: Make sure your cannabis plant is being grown in fast-draining soil with holes at the bottom of the pot to let excess water escape. Space out your
watering sessions until your weed plant’s condition returns to normal.
Too much fertilizer
Compost and fertilizers are usually an effective means of encouraging healthy marijuana plant growth. However, excess fertilizer can be detrimental to your autoflowering cannabis plant.
Over-fertilizing can transform your autoflowering cannabis plant’s soil into a toxic pool overflowing with nutrient salts, which can cause your plants to suffer from
fertilizer burn. It can lead to your plant’s leaves canoeing up, wilting, and producing low-quality buds.
Solution: Use water to
flush out your pot plant’s soil and dial down the fertilizer usage. If this does not resolve your
over-fertilizing crisis, consider transplanting your cannabis plant into new soil and container.
Heat stress
Temperatures above 30 degrees Celsius are dangerous for your autoflowering cannabis plants, especially if they are young and have not yet developed a complete root system. Extended exposure to the sun’s scorching heat can stunt your marijuana plant’s growth.
You will know your plant is suffering from heat stress if you see your cannabis leaves canoeing up along with the presence of yellow-brown spots on leaves.
Solution: If your autoflowering cannabis plants are being grown outdoors, use a piece of cloth as an outdoor shade against the sun. Water your plants early in the morning to keep them cool. Try using ceramic pots to insulate your plant’s roots against the sun. (
Pro Tip: Seaweed kelp extract is known to help heat-stressed plants recover quickly!)
Windburn
Too much wind can cause your autoflowering cannabis plant’s leaves to cup upwards. Wind-stressed cannabis plants curl up their leaves to protect themselves from strong winds.
If you notice that leaves positioned further away from the wind do not show signs of canoeing up, then your plant may be
suffering from windburn. If you do not address your plant’s windburn, it can lead to injured leaves, weak growth, and a poor harvest.
Solutions: Use fans which have multiple strength settings so that you can adjust the airflow. It is a good idea to point fans towards your autoflowering cannabis plant such that there is a gentle gush of air above your weed plant’s canopy, and another flow right underneath the leaves. Remove leaves that have been damaged too much by windburn.
