Looking at a cannabis plant, it all seems so simple… Give it some water and nutrients, and just watch that marijuana crop grow into a fine harvest full of big flowers buds. Inside those cannabis plants, however, there’s a lot going on to make all of that happen. In addition to water and nutrition, light is another crucial ingredient needed to make them grow. It is the key ingredient for photosynthesis, by which cannabis turns light into energy needed for growing and flowering. This blog teaches you how photosynthesis works, and how it affects the production of cannabinoids.
Table of Contents
The Magic Of Cannabis Photosynthesis
Plants can do something that people can’t: they are able to live on light. Of course, plants also need water and nutrients to grow, but light is just as essential for the process. This light is provided by the sun, or by artificial lighting in case of growing cannabis seeds indoors. But what actually happens inside a cannabis plant when photosynthesis occurs? Here’s the lowdown:
Plants are capable of turning light into energy and nutrition by merit of their internal biochemistry. Looking at a plant of any species, the first thing to stand out is its green colour. This is an important fact in terms of photosynthesis, since the green colour of cannabis and all other plants is caused by a substance called chlorophyll. In addition to giving plants their lovely green hues, though, chlorophyll can also absorb light.
The process of photosynthesis in cannabis takes place in the leaves; specifically, in their mesophilic cells. These cells are located right underneath the surface of the leaves, allowing them to capture the maximum amount of (sun) light. Chlorophyll in leaves can absorb red and blue spectrum light, freeing it up for energy storage through a complex chemical reaction. Photosynthesis consists of two steps: the light reaction and the dark reaction.
Light Reaction:
This reaction occurs when sunlight is available during the day; or when the lights are switched on in case of indoor grow rooms. At this stage, CO2 enters the leaves through the tiny openings called stomata located on the leaf, while the roots absorb water and nutrients. The plant transports these ingredients to the cells. During the daytime (or light time, if you will), weed plants catch the light emitted by grow lights or the sun. This light energy hits the leaves in the form of photons, crashing into the chlorophyll molecules. This triggers reactions in the plant cells that eventually allow for storage of energy in ATP and NADPH molecules.
Dark Reaction:
After sunset, or after a grower turns off the lights, another process begins. The energy that was stored during the day can now be used to turn CO2 into glucose, in a process known as the Calvin cycle. This enables plants to feed off of light: glucose is a sugar used both as an energy source and for building larger carbohydrate molecules.
How Much Light Does Cannabis Need For Photosynthesis?
When growing cannabis seeds, there are major differences between indoor and outdoor grows. Outside, cannabis plants get natural sunlight by following the seasonal rhythms. They grow and flower in accordance with a life cycle dictated by the hours of sunlight they can catch. Indoor growers can adjust the amount of light received by their plants. In the vegetative stage, indoor growers usually give 18 hours of light a day; sometimes even 24 hours. The flowering stage is usually marked by 12 hours of light and 12 hours of dark. Plants grown outdoors start to flower after the summer solstice, as the days grow shorter and the plant responds by producing flowers.
The big exception to this rule are autoflowers. Autoflower marijuana seeds contain cannabis ruderalis genetics, allowing them to decide for themselves when it is time to flower.
Photosynthesis And Cannabinoid Production
With light being such a dominant influence on the growth and flowering of cannabis plants, you might expect photosynthesis to be a determining factor in cannabinoid production. So is that true? Can faster photosynthesis give a plant more energy to produce more cannabinoids? This is not an extensively studied topic. However, one study by Canadian Guelph University’s School of Environmental Sciences seems to indicate that lighting type and intensity can alter photosynthesis speeds. Still, this has not been clearly demonstrated to affect the quality or quantity of cannabinoids produced by the plant.
Whether cannabis seeds are grown outdoors or in, light is a vital resource for marijuana plants. Out in the open air, they get to enjoy the sunlight all day long, whereas inside, growers need to use artificial lighting. These will make cannabis crops thrive just the same, however. Did you know that certain grow techniques can help your plants make the most of all available light? You can read all about in in our Grow Blogs, such as the ones on Low Stress Training, or on trimming and defoliation.