420 Trainers

What can Cannabis leaves tell you?

In order to be able to identify if your plant has any health problems, you need to examine its leaves on a daily basis. Cannabis leaves can tell a lot about the plant, from its genetics to its overall health and vigor. 

Types of Cannabis leaves.

There are three types of Cannabis leaves. 

Sativa: Sativa plants have narrow leaves which grow best in warm environments. Usually, sativa plants will have a lighter, lime green shade, indicating a relatively low amount of chlorophyll.

Indica: Indica plants tend to have wide, short leaves with short wide blades. Healthy indica leaves are marked by their darker, deeper shade of green. 

Hybrids: Hybrids, as you might guess, fall somewhere between the two. Many hybrid plants have medium height and leaves with moderate thickness.

There is always an odd number of leaves in regards to cannabis plants, with the highest number of leaves on sativa plants, then indicas and hybrids. Five, seven, and nine leaves are the most common numbers seen. 

Unhealthy Cannabis Leaves

Unhealthy cannabis leaves may be yellow or brown in color, either a solid color or splotches/ streaks of discoloration. The leaves may also curl and become crisp to the touch. 

If you notice this trend on your plants, maybe in a couple of leaves, this may be signs that your plant is trying to tell you that something is wrong. 

Fan and Sugar leaves

Another characteristic to differentiate leaves from one another is the type of leaf.  

Cannabis plants have two types of leaves. Fan leaves and Sugar leaves. They can be found in different parts of the plant and have different functions.

Fan leaves

These leaves are large, fan-shaped leaves, whose main purpose is to undergo photosynthesis. These leaves can also serve as emergency storage for certain nutrients like nitrogen. If the plant cannot get them from the soil, it can draw stored nutrients from the leaves.

Sugar Leaves

The sugar leaves can be found nestled within and extending from the buds. A “frosting” of white trichomes covers their surface, which is the inspiration for their name. Essentially, the function of sugar leaves is to give structure to the buds so they stay together.

Main causes of leaves curling.

Overwatering.

The first and easiest step in determining the source of curling leaves is overwatering.

Overwatering puts the plant at risk of drowning and bud rot, as well as providing the perfect setting for Pythium, the parasite that causes root rot. Cannabis leaves curl due to both waterlogging and root rot.

Luckily, it is easy to correct. Before watering your plant, make sure to check the leaves. If they appear to be dropping and appear to be developing slowly, and the soil is dry to an inch deep or more, it is time to water. If not, you should wait. 

Under watering.

Under watering causes symptoms that often look like overwatering, but you will know it is under watering if the plants perk up each time after you water them.

Pests

Pests can damage cannabis plants in a variety of ways. They are not necessarily easy to see but the negative effects they invoke will be very noticeable. Aphids and mites, which live on the undersides of leaves and feed on the nutrients within, are two of the most frequent troublemakers to mess with weed plants.

A tip to prevent this is whenever you spray plants with anything; make sure to get the undersides of the leaves too, as this is where many pests like to hang out! 

Over-Fertilizing

Over-fertilizing is a common problem amongst new growers. Many feel that the more nutrients you give the plant, the more it will grow, but that is not the case. If a plant receives too many nutrients, it will become a toxic level, which would kill the plant. 

If you avoid over-fertilizing your plants with nitrogen early on but over-fertilize them with potassium or phosphorus throughout their flowering time, you will promote curling. Apart from curling, the tops of the leaves are prone to burn.

To cure over-fertilization in soil, you need to rinse out the soil. You will want to heavily water the plant, and have lots of water coming out the bottom of the pot. This will ensure the excess nutrients are washed away with the water.

Temperatures are too high

Cannabis plants love sun, but when it gets too warm, they are unable to properly photosynthesize. Cannabis plants can generally photosynthesize and be happy in temperatures up to 82.4F. (28C.). Beyond that, you may notice the leaves curling, and the plant not thriving. Often the leaves will “canoe” which essentially means they take on a canoe shape, as the leaf margins curl inward.

It is simple to adjust and reduce the temperatures for indoor growers, and you may use an air conditioner to do so. Regulating temperature or heat exposure for outdoor growers can be difficult. Most growers, on the other hand, use a screen to offer shade and keep cannabis plants a little cooler.

Temperatures are too low

Curly cannabis leaves can also be caused by cold weather. Leaf yellowing of various types will eventually appear. While colder night-time temperatures late in the flowering cycle might give buds a purple sheen, prolonged exposure to temperatures below 50F. (10C.) can destroy your plants. 

The solution is simple. Simply move the plant out of the cold environment, or warm up the environment. This is harder to do with an outdoor setup since you cannot control the weather; but if your plant is in a pot, you can move it to a location with less wind, where it will be less exposed.

To conclude, there are many reasons why Cannabis leaves may curl, luckily, most of these reasons have an easy solution. The best thing you can do is get educated on the subject and do not panic if it happens to you, it happens to most growers at least once. Just follow these quick tips and you will be good to go!