Curly cannabis leaves are something that happens when plants don’t feel they are being looked after, and there a several reasons for why you might find them in your garden. Curly leaves are indicators from plants, designed to let you know that they need some attention – don’t ignore these signs, doing so could be detrimental to your final yield.

One of the most common causes of curly marijuana leaves is overwatering. Overwatering is one of the worst things you can do to a plant because doing so will drown its roots, washing away helpful microbes and could eventually lead to root rot. Furthermore, too much water can aid in algae and fungi growing in and around your plant – and nobody wants that. The best way to monitor your plants water-content is to use a moisture metre, which will help you maintain an effective wet-dry cycle.

Another reason why plants leaves curl up is overfertilization. Fertilising your plants too much can cause leaf-clawing. While your plants do indeed need lots of nutrients, it best to take a light approach so as not to over-do it. The most efficient way to give your plants the nutrients it needs is to start as low as possible and work your way up – you can always add more, but you definitely can’t take nutrients away once you’ve given them. Also, keep in mind that the pH of your soil should always be approximately 6.0pH.


Cannabis plants are also incredibly sensitive to heat, so much so that if a plant is too warm, it will begin to show major signs of stress – such as leaf curling. Marijuana plants photosynthesise best at between 28°C and 30°C, anything more than this and your plants will seriously start to suffer. On the other hand, plants can also start to show signs of distress when they get too cold. Any temperatures below 10°C are guaranteed to destroy your harvest.

The best advice I can give you is to do some research on the exact strain that you’re growing before you start taking generalised advice, because different strains and varieties will have different ideal growing conditions. Curly cannabis leaves are a huge hindrance and can be the difference between plants living and dying, so it’s important to take the correct preventative measures to stop it from ever happening to your grow – hopefully this guide has done just that.

Amsterdam Marijuana Seed Bank