Growing Cannabis 101

Growing Cannabis can seem intimidating to the uninitiated but the truth of the matter is that can easily be done by most. This growing Cannabis guide will take you, through all the stages of the growing cycle and provide you with the information you need to grow your first cannabis plant(s).

Choosing your seeds

First, choose a variety of Cannabis seed you want to grow. Ask your seed retailer all the questions you have, and explain the way you want to grow the plants. If you are growing them outside, it might be wise to choose a quicker flowering strain that will finish before it gets too cold. If you need Cannabis for medicinal reasons you must be very specific when choosing your variety- make sure that you are growing the right medicine.

Most importantly, remember that Cannabis is a plant, and can be grown as easily as many other annual flowering plants. Nature takes care of most aspects when growing outdoors. As the seasons change, the plants receives the right amount of daylight for both growing and flowering. All you need to do is to give water during dry periods and perhaps add some organic fertilizer.

Indoor growing requires a little bit more work; you have to provide your plants with all the elements they need to survive: sunlight (special lamps), seasonal changes (timers), fresh air (exhaust fan), and wind (circular fan), earth (pots with soil or another medium), and rain (water and nutrients). If these elements are provided, all you need is a basic understanding of the plant’s natural life cycle.


The process of seed germination happens the same way for both indoor and outdoor growing. When purchased, the seeds are very dry and need to absorb a lot of water before they will open. This can be done in various ways but the most natural one is to simply place the seed in soil and then water it. The preferred method used by us in the Amsterdam Cannabis College is referred to as the “saucer technique”.

The Saucer technique

You will need:

  • 2 saucers or small plates
  • Kitchen paper
  • Water

Place the seeds in between two layers of kitchen paper on one of the saucers. Wet the saucer so the paper is fully moist, yet not soaking wet and the place the second saucer on top of the other to prevent the seeds from receiving any light.

Check the seeds periodically (every 12 hours) for signs of sprouting and to make sure the paper is still moist.

This process can take anywhere from 12 hours to several days.

Once sprouted, gently place the seedling about 5mm deep in a small pot containing your growing medium of choice with the root facing downwards. Using Organic fertilizers can be added to improve plant growth and health. The plants really like Nitrogen (N) during this grow cycle. propagators can create a more stable environment best used for clones and seedlings, especially for the first few days. Keep the soil moist (but not wet), until the first leaves emerge.

Once the plants have settled in the soil you can add some root stimulating fertilizers, but not much to avoid burning the roots.

Young plants do not need intense light. Do not place them too close to high intensity lights or they will burn. Fluorescent tubes can be used indoors for young seedlings as well as for clones.

Remember that Cannabis is a plant, and can be grown as easily as many other annual flowering plants.

Organic fertilizers can be added to improve plant growth and health. The plants really like Nitrogen (N) during this grow cycle.

Industrial hemp

Vegetative phase

(18 hours of light, 6 hours of darkness)

Growing Cannabis outdoor

Cannabis can be planted outdoors as soon as your area receives enough hours of daylight, which is between 16 and 18 hours of light on a daily basis. In Europe, this happens between May and June. During its vegetation (also known as the grow phase), the plant can be bent and/or trimmed to keep its size and shape under control. They will continue to grow until the hours of daylight reduce to around 12 hours a day. This will trigger the plant to flower.

Growing Cannabis indoor

The plant requires 18 hours of light daily during its vegetative phase. It is easiest to use a timer turning the lights on or off when required. The entire grow cycle can take place in as little as 2 weeks for a small plant to 4 or 5 months depending on how large you want your plant to be. It’s fully up to you!

Equally important as the lights is the period of darkness they receive every day. There should be 6 hours of uninterrupted darkness per 24h period.

Watering should be done only when the top layer of the soil is very dry. This means once every other day. If the soil is still moist at the end of the second day, then you know you gave too much water the time before and should use less the next time. This is to prevent the higher layers of roots from drowning.

Organic fertilizers can be added to improve plant growth and health. The plants really like Nitrogen (N) during this grow cycle.

Note: pH levels should be kept between 5.8 and 6.5

Flowering phase

(12 hours of light, 12 hours of darkness)


When growing Cannabis outdoors, plants will start to flower when you get only 12-14 hours of daylight every 24 hours. In the northern parts of Europe, this occurs around August through September.

Flowering times differ per Cannabis variety and can take anywhere from 6 to 18 weeks. Make sure to grow a variety that flowers quickly when growing in colder, more northern climates.


When growing Cannabis indoors, plants need 12 hours of light and 12 hours of uninterrupted darkness to be able to flower without any “light stress”, which could disturb the plant’s natural cycle and interfere with the flowering process.

Autoflowering varieties

Autoflowering genetics differ in that the plant will automatically start to flower after a given time in the vegetative phase, regardless of the light conditions it is placed in. Certain growers prefer to maintain these plants under a constant light schedule of 18 hours to prevent any stress for the plant.

Sexing your plants

Shortly after being put into flower, plants will show signs of their sex.

Male plants will develop pollen pods whereas female plants can be identified by their small white hairs otherwise known as pistils.

Male plants should be removed as soon as they are identified in order to prevent pollinisation taking place and the female plants producing seeds.

The maturation process

Leaves will slowly start to turn yellow and shrivel after the 3rd of 4th week of flowering. When a leaf does so, it should be carefully removed from the plant and disposed of. Make sure not remove too many green leaves however as this could diminish the plant’s ability to photosynthesize.

Watering should happen in a similar way to when the plants were growing but fertilizers containing phosphorous (P) and potassium (K) are to be used for stronger, healthier plants with a higher yield. It is very important to stop adding fertilizers to the water two weeks prior to harvesting your plant in order to flush most nutrients out of it, improving taste and quality.

Note: flowering plants need as much light as possible. Do not place a plant in the shade or too far away from the grow light. Use chains or a pulley system to adjust the height of the lamp to enhance the light’s diffusion.

Make sure to grow a Cannabis variety that flowers quickly when growing outdoors in colder, more northern climates.

OG Kush Automatic from White Label Seeds
OG Kush Automatic from White Label Seeds in full bloom

Organic fertilizers can be added to improve plant growth and health. The plants really like Nitrogen (N) during this grow cycle.

Harvesting & drying

This is a painful moment for most growers after taking care of the plant for so long as it is now time to chop it down. As soon as the resin gland or trichome has matured, it is time to harvest the plant. The branches can be cut off and hung upside down in a dark and well ventilated space until they are completely dried. This can be tested by bending a branch. If it bends, it is still moist. If it breaks or snaps, it is dry enough to be stored.

Growing Cannabis - drying

The drying process can take up to 3 weeks for bigger branches and as little as 6 to 7 days for smaller buds.

As soon as they are dry, the remaining leaves can be removed as they should not be smoked or vaporized. They can however be used for tea, “space” foods or hash-making.


After drying, the cannabis is almost ready to be consumed. Now comes the hardest part when growing cannabis.

For a better product, the cannabis should be cured. This process is similar to that of ageing a fine wine. Curing should be done in glass jars, stored in the dark for about 2 to 4 months. This will slightly change the colour of the flower as the chlorophyll will start to break down. The taste becomes more distinct and the smell more pungent due to the fermentation process that occurs.

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Frequently asked questions

Is it hard to grow Cannabis?

Cannabis is an easy plant to grow. It is not called a weed for no reason. Refer to our Basic growing guide for more information.

What Cannabis seeds should I choose?

This is a difficult question to answer. Seeds come in different forms: regular seeds producing both male and female plats, feminised seeds, and autoflowering seeds. Each has its advantages and disadvantages. Choosing the ones best suited to you depends on what your are looking for from your cannabis plant and your level of experience.

How long does it take to grow Cannabis?

This depends on the Cannabis variety you are growing and its environment. Life cycles can vary from two and a half months for autoflowering varieties to more than 18 months for certain sativa varieties.