Introduction to growing Marijuana


If we search the web for content about marijuana, it is very possible that it is one of the most studied, discussed, controversial crops and about which there is more information. All this is at least curious since as we all know, its consumption is prohibited or regulated in many countries and its legalization is a social gap that has been in the limelight for decades.

At Gardenprue, we also want to talk about it without entering into consumer debates, legalization, etc. That is already a matter of each one. Today we want to talk about cannabis from the technical aspect, its needs for water, light, nutrients, phases of the plant … which after all is what we usually talk about in this blog. When we say easy it is because there is so much technicality that it is difficult to err in its cultivation. We believe that it is more difficult to care for orchids xD.


It is clear and I believe that nobody has the doubt that cannabis belongs to this family. There are more genres and a well-known relative of marijuana is neither more nor less than hops or Humulus L., a plant so well known for its use in brewing beer.


When it comes to growing marijuana, there is no doubt that what you are looking for are female plants, which are the ones that concentrate the highest amount of THC. We are not going to fool ourselves, this is exactly what we are looking for in this plant. It is a dioecious plant like many others, see kiwi, holly, date palm or hops that we just mentioned. Here we show you an image of a miniature book from the 16th century, the Great Hours of Anne of Brittany, where illustrators showed the dioecious character of Cannabis sativa, in 1503 no less!

Cannabis sativa. Book of Hours of Anne of Brittany (16th century)


This is a whole world. There is no end to the varieties and hybrids created for decades. There are varieties of all kinds, even differentiated for indoor and outdoor cultivation. Outdoors, fast-flowering varieties have been selected to avoid post-flowering cold as much as possible. Today seeds of all kinds are sold: autoflowering, hybridized between different species … even with different aromas … even sweet! Here is an example where you can buy sweet seeds (sweet and caramelized in aromas).


Given the social impact and the persecution of large-scale cultivation, cannabis cultivation has become highly specialized in controlled indoor environments as we manage to adjust the cultivation conditions to optimal levels without stressing the plant at any time. Let’s say we have them in incubation. On the other hand, the plant is immediately betrayed, either by the strong and well-known smell that it gives off or by its appearance. We are sure that almost 100% of people would recognize the appearance of a marijuana plant faster than a tomato (for example)… ;-).


Light is one of the most controlled aspects of indoor growing. There is a large catalog of lamps (light temperature, type of light, color …), timers, etc. to control the photoperiod of marijuana cultivation. As a guideline, the plant needs about 18 hours of light per day and 6 hours of total darkness (18/6 photoperiod) in its vegetative period until flowering. When the plant is of an adequate size, flowering is induced by gradually lowering the photoperiod until 12 hours of daily light (12/12 photoperiod). It takes a few days for the plant to recognize it, at which point the phenological state changes and flowering enters the scene. Unless we want to obtain seeds, we cannot allow male plants (if we have them) to produce mature pollen.

We will have to remove them first. In the market there are many examples of stores specializing in the acquisition of hybrids, only female, such as the  sale of seeds in Yervaguena . With this it is possible to avoid unwanted pollinations and future problems.


As in any plant, according to your needs, there will be substrates that respond better than others. With this we do not mean that a universal substrate is not worth it, of course it is worth it, but given the great technification of this crop, there are substrates with optimal pH, the necessary slow-release nutrients, elements that give the substrate moisture retention and book drain, specifically designed for growing cannabis. One of the most used elements as a substrate is coconut fiber, which we have already talked about on occasions on the blog. As a general rule, cannabis requires a normal pH like that of many plants (between 6 and 6.5) with slight variations that will not involve major changes in its development.


It does not require more watering than any normal plant. Avoid puddles and get frequent irrigation by letting the substrate dry on the surface (remember that 4 fingers below the surface, the substrate will still contain some moisture). During flowering, the irrigation frequencies will be similar, perhaps with a little more spacing between waterings but practically the same.


The needs, like all plants in the vegetative period, are basically N. In the flowering period, P and K come into play. The ready-made substrates that we have mentioned above bring the optimal nutrients for the crop. This does not mean that we cannot grow marihauana in a normal substrate, adequately fertilized for example with mature compost rich in organic matter. Vermicompost is very suitable for this crop. It is highly enriched in nutrients and we get the worm to provide a good structure to the substrate, improving drainage.

In short, a whole world that we could be writing about until we crush the pc keyboard. Today is a small introduction but we will talk at length …

All the best!

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