Understanding and using cannabis leaves
Cannabis leaves can tell a great deal to the experienced gardener. Once you know what to look for, the appearance of cannabis leaves allows you to understand several important factors which affect the health of your plants. Cannabis leaves also allow you to understand the nutritional needs of your plants. If you can interpret and apply the information conveyed by the leaves you will be well on your way to becoming a more skilled and successful cannabis grower. This will allow you to increase the quality and quantity from each harvest. Read on to find out more.
The different types of cannabis leaves
Cannabis leaves are crucial to the health of your plants. Disease, over-watering, virus damage, under-feeding, pests, over feeding, mold, under-watering and many other problems can be seen on your plants leaves if you know what to look for.
Leaves contain the natural pigment called chlorophyll. This allows photosynthesis to occur in the leaves, converting light energy into chemical/biological energy for growth. On the under side of leaves are small pores called stomata. During photosynthesis these allow carbon dioxide to enter the cells as well as allowing oxygen and water vapour to escape. Cannabis leaves are remarkable pieces of multi purpose cellular technology, they can also absorb nutrients fed directly to them in a process known as foliar feeding.
The shape and structure of cannabis leaves tends to vary slightly between the different types of cannabis.
Indica cannabis leaf appearance
Leaves grown from indica cannabis seeds tend to be wide, fat and short. Often you can expect around 7-9 fingers on the leaves. These leaves can be surprisingly large, especially from a pure indica strain such as an Afghani.
The wide, broad leaves from indica varieties can prevent light penetrating too far down. This makes some indica strains less suited to e.g. SCROG grows. Indica leaves often have characteristically deep/dark green leaves. This is a sign of high levels of chlorophyll present in the cells of the leaves. High chlorophyll levels in indica strains is thought to assist the rapid bloom times.
Sativa cannabis leaf appearance
Cannabis leaves grown from sativa cannabis seeds often have slimmer, more narrow leaves with slender fingers. You can see up to 13 fingers on some sativa cannabis leaves. The thin structure of sativa leaves allows light to penetrate down to lower levels. Cannabis leaves on a sativa may not be quite as dark as those on an indica, indicating lower chlorophyll levels which are thought to result in longer bloom times for sativas.
Ruderalis cannabis leaf appearance
Ruderalis leaves tend to be slim, with as little as 3-5 fingers. Some people think they resemble the leaves of sativa seedlings.
Hybrid cannabis leaf appearance
Cannabis leaves grown from hybrid cannabis seeds often display appearance characteristics from both indica and sativa leaves. With a hybrid strain, leaves are often not quite as slender/slim as a sativa. The leaves are also not quite as stubby and fat as an indica. Instead, the hybrid cannabis leaf has similarities drawn from both indica and sativa leaf shapes.
Most common cannabis leaf pattern mutations
As you gain experience with successive cannabis grows you will also start to recognise and understand more about cannabis leaves. If you are observant and curious you will learn a great deal about the leaves and what they can tell you about your plant, its health and its possible needs. There is also a great deal to learn simply about the different types of leaves which can be found on cannabis.
Cannabis leaves have a distinctive, iconic shape. The standard cannabis leaf shape is recognisable by most people. But few heads would be turned by webbed cannabis leaves. Dutch Passion have the world’s most successful webbed cannabis leaf variety with their Frisian Duck strain. The beauty of this strain is that a stabilised natural leaf deformity provides perfect stealth for any cannabis plants which you have growing outdoors. Most people would fail to recognise the plants as cannabis.
If you are keen to grow some plants with a unique cannabis leaf shape them you should take a close look as Frisian Duck seeds and Auto Duck seeds.
Traditionally, two cannabis leaves are produced at each internode. With whorled phyllotaxy plants there are three leaves instead. This can produce a slightly bushier structure to the plants. Whorled phyllotaxy is a somewhat fragile genetic anomaly, it usually disappears quickly when attempts are made to stabilise and replicate the property.
Just the same as webbed cannabis, genetics (used in Frisian Duck seeds and Auto Duck seeds) causes the individual fingers of the cannabis leaf to ‘web’ or mesh together, The result is a leaf which has the same shape as a ducks footprint. Hence the name, ‘Ducksfoot’ cannabis. This unusual leaf appearance is loved by garden growers and outdoor growers, since the ducksfoot leaf shape rarely attracts a second glance and easily blends in with natural vegetation.
Variegated cannabis leaves contain both green and white parts to the leaves. The green parts contain chlorophyl and can photosynthesise. The white parts of the cannabis leaves contain no chlorophyl making photosynthesis impossible. A surprising number of plant species show variegation in the leaves, suggesting an origin deep back in plant evolution. It’s a mutation, but one which plants can live with.
This is most common in tropical strains. Lower branches from creeper cannabis plants bow down and trail along the ground. Along with other plant species, cannabis can occasionally allow these creeping/trailing branches to take root if the conditions are right.
This is an unusual mutation and so far no uses have been found for it, meaning that no cannabis seeds or strains have been produced with this trait. Potentially, it is interesting for outdoor growers or those looking to increase stealth growing properties.
Vine cannabis is a curiosity which has so far not made it into a commercial cannabis seed. With Vine cannabis the stems and branches can twist around each other in a ‘vine’ like growth structure. Some associate this with ABC (Australian bastard cannabis), perhaps being an unusual derivative. Cannabinoid levels have never been shown to be particularly high with Vine cannabis (or ABC). As a result, there has been little interest from the cannabis breeding professionals to convert this into a new cannabis seed variety.
Bud sites often originate at the nodes of cannabis plants. However, from time to time is a seemingly random mutation, buds can also form at the base of a leaf where the leaflet fingers join together. Leaf buds are random mutations, they don't contribute any significant boost to yields, but they are a pretty way to impress your friends!
Polyploid cannabis is a condition in which the cells have more than two paired sets of chromosomes. Most species whose cells have nuclei are diploid, meaning they have two sets of chromosomes—one set inherited from each parent. Polypoidy is common in nature and a definite curiousity to cannabis breeders.
Some believe that polyploid cannabis will have the potential for greater cannabinoid content and potency. However, so far, no-one has been able to create feminised polyploid cannabis seeds. However, research continues, so watch this space!
What is polyploid cannabis?
Upright mutations are most often seen in plants grown from hybrid cannabis seeds. The mutation, which is a severe inconvenience for indoor growers, causes the plant to grow in a massive way, much like a tree. Heights of over 4m are possible with this ‘random’ mutation, which is difficult to control with breeding. Yields are of course excellent, but for indoor growers this rare mutation brings no benefits.
Occasionally, but rarely, you will get two seedlings from one individual cannabis seed. Think Different is one Dutch Passion autoflower seed which is particularly prone to this mutation. If you are careful, you can untangle the roots from the twins and you will get two adult plants from them. If you get twins, you will be one of the few growers that can boast germination rates in excess of 100% !
Foxtailed cannabis can be seen when one calyx grows on top of the previous one in a sequential fashion. Instead of growing into a ‘ball’ shaped bloom, the bud grows in a more delicate, stacked, way. The buds are slender and elegant, rather than fat and heavy. That’s one of the criticisms of fox tailed buds, many growers would prefer to see traditionally shaped buds with the heavy yields they are used to.
Heat and light stress can cause cannabis buds to foxtail, though some genetics are inherently prone to it.
Australian Bastard cannabis
First reported from the Sydney area of Australia in the 1970’s, this is an unusual looking strain sometimes with round, small, shiny leaves. Examples with longer, spear shaped cannabis leaves are also possible. It looks little like cannabis, perhaps more like a garden shrub/herb. With limited cannabinoid content, these genetics have so far attracted little interest from cannabis breeders.
Cannabis leaf phyllotaxy: arrangement on a plant stem
Because cannabis leaves have numerous individual leaflets (sometimes called ‘blades’ or ‘fingers’) the leaves are classified as ‘compound’ leaves. The other type of leaf is called ‘simple’, such as those seen on herbs such as Basil.
When you grow a cannabis seed a seedling grows and leaves emerge in pairs on opposite sides of the stem in an arrangement known as opposite decussate. The gap between one set of leaves and the next set is called the internodal distance. Short internodal distances are more common with plants grown from indica cannabis seeds. Longer ‘stretchier’ internodal distances are seen on plants grown from sativa cannabis seeds.
When cannabis is in flower you can see alternate spiral arrangements of the leaves as the set starts to stretch and internodal distance increases.
Cannabis photosynthesis: why do leaves change colours?
One of the great joys of cannabis cultivation is seeing your prized plants approach bloom. Not only do you experience the rich aromas of harvest and see the blooms and resin go into overdrive. You may also see the natural beauty of the leaves taking on some autumnal shades as the leaves gradually change colour.
Your green leaves may start to fade revealing some beautiful red, yellow, purple/blue, orange (and other!) hues. For the cannabis connoisseur this final colour display can seem like the best part of the grow. Even the buds can start to display some great new colours. But why do your plants show these different leaf colours? Which chemicals and pigments cause these changes?
The role of Anthocyanin
Changes in cannabis leaf colour are thought to be related to the appearance of a family of natural water-soluble plant pigments called anthocyanins. As well as being found in cannabis, anthocyanins are responsible for the colours found in blueberry, raspberry, black soybean and many other plants. Carrots were originally purple due to anthocyanins before some clever European breeders produced the orange ones which we are familiar with today.
Anthocyanin compounds can take on several different colours. These range from red, blue, black and purple. Small pH differences at plant cellular levels can cause striking colour changes. You can see the colours in the stem, leaves, branches, buds, trichomes and occasionally the roots.
Low temperatures in bloom encourages the formation of these colours. For cannabis connoisseurs, the presence of extra colour in your buds only increases the bag appeal. Some genetics are also prone to producing these colours, for example Auto Blackberry Kush seeds can produce phenotypes with very dark purple buds. A lack of Phosphorus in bloom is also suspected to enhance colour production.
Purple and blue cannabis strains
If you love buds with blue/purple hues then there are several strains which tend to produce colourful phenotypes.
Auto Blackberry Kush seeds. With genetics from Blueberry x Hash Plant, these autoflower seeds are easy to grow. They take around 10-11 weeks to grow from seed to harvest under 20 hours of daily light.
Auto Blackberry Kush grow review
Feminised Blueberry seeds. Though many phenotypes are green, you may be lucky enough to get a coloured phenotype. Especially in cooler bloom conditions. Auto Blueberry is also available for lovers of high quality autoflower seeds.
Red and pink cannabis strains
Auto Banana Blaze seeds, especially when grown in cooler bloom conditions, can produce some beautiful warm red/pink colours. The great bag appeal combines with a satisfying and enjoyable high alongside heavy yields.
Cannabis deficiencies and nutrient problems
If the cannabis plant is short of essential nutrients or minerals you can often see the warning signs on the cannabis leaves themselves. This is one area where the experienced cannabis grower can put their knowledge to huge advantage by ‘reading’ the leaves.
Often the health and appearance of the leaves are one of the first signals from the plant that not all is well. When a plant isn’t watered you will notice that the plant wilts. That’s the simplest signal that the leaves give us and it’s a signal which most growers would understand. As you gain experience, try to understand more about leaf health/appearance and the signals which they give about nutrient issues. Many detailed/illustrated books exist which can help, as can online resources.
What to do with cannabis leaves?
In the rush to chop, trim and harvest their buds, many growers simply discard the leaves. After all, the blooms provide most of the eventual pleasure. But if you can be bothered with a little bit of extra work, you can easily turn your leaf trash into stash. Below are a few proven options:
Turn sugar leaves into hash or kief
All those small, resin soaked leaves are a rich source of resin. Once you have finished trimming your buds, save and dry the best of the leaves which are often called ‘sugar leaves’ since they appear to have been sprinkled with sugar.
Once the leaves are dry they can be turned into kief simply by shaking the leaves above a fine screen which will allow the dry trichomes to pass through and be collected. Or you can make your own hash, e.g. using the ice water method.
Make homemade thai sticks
Thai sticks are an ancient creation. Buds are tied to a stick or skewer to cure. Sugar leaves can be pressed in with the buds and in some cases some cannabis oil (hash oil) is used to help bind it all together. The sticks can then be wrapped in sticky fan leaves. Many thai sticks were brought home from the vietnam war by returning troops. Some people suggest that the remarkable potency of these legendary thai sticks was increased by the addition of opium.
Press trim to extract rosin
Once you have harvested and manicured your buds you can collect and dry the trim to produce rosin. Rosin is made by pressing two metal plates together. Often the metal plates are heated, to assist the process of squeezing out the oil. The trim/sugar leaves need to be dry otherwise you will also produce a lot of water in your rosin. Note that rosin that is pressed from trim won't reach the same quality level as rosin that is pressed from high quality buds.
You can buy specialist rosin presses. Or you can use a pair of hair straighteners. Put your buds in some grease proof paper, heat up the hair straighteners and squeeze the buds hard for a minute. The cannabinoids and resin flow out from the bud onto the grease proof paper. Your rosin extraction is complete, and you didn't use solvents to make your cannabis concentrate!
Make cannabutter and edibles from leaves
Many people make cannabutter from their spare cannabis leaves. Often the leaves/trim are put in a pan containing boiling water and butter. The butter dissolves all of the oily compounds and cannabinoids from the plant material. The mixture can be poured through a cheesecloth filter to remove insoluble plant matter. Once cool, place the pan in the fridge. The butter sets solid, save it and pour away the water. Then you have your own canna butter to use in cooking!
How to make the best space cake
Use leaves as dry herb for food-seasoning
It’s not to everyone’s taste, but dried/ground trim can be used as a seasoning to add flavour to your food and snacks. This could be added to a warm stew or a cold salad.
Juicing fan leaves
Some people simply collect all their trim and unwanted leaves and put it in a food blender to be liquidised. Often, other ingredients (ginger, fruit etc) are added to improve the flavour. This could be sweet ingredients such as chocolate/milk (e.g. to make a smoothie) or savoury ingredients. So long as the liquidised mixture remains unheated it will not allow the THCA to convert to THC. This means that you will not get high from your juiced fan leaves.
Frequently asked questions and recommendations
Many growers feel a little bit guilty for not using their cannabis leaves and just throwing them away. It doesn't take that much effort to turn your plant waste into genuinely useful products. In legalised cannabis markets such as North America, there are specialist firms which buy and collect waste trim and leaves from licensed growers. Usually this is turned into cannabis concentrates. Here are some of the most frequently asked questions about cannabis leaves.
How long for cannabis seeds to get their first set of leaves?
When the cannabis seed germinates you usually see a pair of cotyledons. These can be thought of as baby leaves, they allow the seedling to start photosynthesis even before the first true set of leaves (with the distinctive serrated edges) appears. The first set of true leaves can be seen with a magnifying glass as they emerge from the node between the cotyledons. Within a week you will see the first set of cannabis leaves.
How many fan leaves before you can start blooming a cannabis plant?
It doesn't really matter. Those that use the sea of green method can even germinate their seedlings under 12/12 light when growing from feminised cannabis seeds. Usually people grow their photoperiod seedlings for 4-6 weeks before flipping into bloom conditions in order to produce heavy yields. You can have many pairs of fan leaves present before initiating bloom conditions or you can have none at all.
Can cannabis leaves get you high?
Yes they can, especially if they are coated in a generous layer of trichome resin glands. The best varieties have leaves which are crusted with resin, and few growers want to throw away such a good source of THC and cannabinoids. The easiest way to get high from them is to vape/smoke them or use them for producing cannabis concentrates such as hash, hash oil, cannabis oil, kief etc.
Can you smoke fan leaves?
Yes, though the taste may not be quite as sweet as well cured buds and can have a slightly bitter taste. Some people find a vaporiser is preferred for getting high from fan leaves. Just choose the best parts of the best fan leaves, grind up and vape!
How to store sugar leaves?
Most of the time growers either fully dry the sugar leaves and trim for subsequent processing. Or they are immediately frozen, for example by those who will eventually make hash using the water/ice method.
Enjoy using your cannabis leaves and trim!
We hope this article has given you a fresh insight into the roles and uses of cannabis leaves. Remember that most professional growers would never consider throwing away their cannabis leaves. With a little effort, you can turn your waste plant material into genuinely potent and hugely enjoyable cannabis concentrates.