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How Cannabis Grows: The Life Cycle Of Weed

The life cycle of cannabis plants comprises several stages. You’ll get better results and bigger harvests once you know how these stages work. It will allow you to care for your weed plants in a better way, tailored specifically to the phase your plant is going through. So let’s explore how cannabis grows, shall we? This blog will show you how to keep your weed plants strong and healthy in each stage of their lives!

How Cannabis Grows: From Seed To Harvest

Cannabis is an annual plant, with a life cycle that spans some anywhere between ten weeks and six months. Differences between strains can be quite significant. Ten weeks is a minimum: some strains take over half a year to complete the cycle. The cycle consists of several stages. First, the plant emerges from its seed to become a seedling. Then, your seedling starts to grow to become a big, strong plant. Finally, the flowering stage arrives, in which female plants develop the flower buds that you can harvest.

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In nature, the changing of the seasons dictates how cannabis grows. As the days start to get shorter, the plants go from the growth to the flowering stage. When autumn draws near, the time for harvest arrives, as with many other plant species. Autoflowering cannabis seeds are the exception to this rule. They are genetically programmed to proceed to the flowering stage by themselves, regardless of seasonal conditions.

A cannabis plant’s life cycle can be divided into four stages:

  • Germination stage;
  • Seedling stage;
  • Growth or vegetative stage;
  • Flowering stage.

Identifying The Stages Of The Cannabis Life Cycle

NOTE: Below, you’ll find descriptions of the overall stages comprising the cannabis life cycle. Please keep in mind that we’re talking biology here: living plants don’t try to fit smoothly into weekly or monthly schedules. Indicas, sativas and hybrids all have their own unique growing paces. These are also affected by situational factors that will differ for weather types, growing locations, and techniques. The images featured are of various strains in different stages and serve as indications only. The point of this text is to paint an overall picture of the four different stages and what to expect as an inexperienced cannabis home grower!

1. Germination Stage

Everything starts with a seed. Moreover, you’ll make the best start with the best cannabis seeds. Looking at weed seeds, the best quick quality check is a close look at their colour and texture. Healthy cannabis seeds feel hard and dry, with light to dark brown colours. When you buy weed seeds, they are still ‘dormant’, or asleep if you will. Packed inside that hard shell is everything the seeds needs to start growing, except one thing: water.

Once you activate your seeds by adding water, they will start to germinate. The protective seed shell bursts open, revealing two growths. One is a tiny root just waiting to dig into the soil; the other is a stem trying to grow upwards. Germination can take anywhere from a few days to two weeks. An easy way to germinate your cannabis seeds is to let them open up on a damp piece of kitchen towel.


Once the root is formed, you can gently put the seed in a flowerpot containing soil. After a few days, the tip of the stem emerges from the ground. After that, two cotyledons or seed lobes appear, ready to catch the first sunlight. From there on, daylight takes over from your weed seed: the plant will now grow by photosynthesis. In the germination stage, your emerging cannabis plant needs 18 hours of sunlight every day.

After this initial stage, your germinated seed turns into a seedling.

2. Seedling Stage (1 to 3 weeks)

At this point, your tiny germinated plant evolves into a seedling over a 2 to 3-week period. The roots start to develop rapidly. They branch outwards underground, after the taproot starts to dig down deeper. The twin cotyledons are now followed by the first two real ‘cannabis leaves’ with their characteristic serrated edges. By now, your seedling should have a fresh, bright green colour. Just like in the previous phase, your plant needs 18 hours of light each day throughout the seedling stage. Be careful not to water seedlings too heavily; the tiny root system doesn’t need much. With its first leaves two leaves catching the light, your seedling is now ready to proceed to the next step in the cannabis life cycle: the growth stage.


3. Growth Or Vegetative Stage (4 to 6 weeks)


Of all the stages involved in how cannabis grows, this one revolves most heavily around growing larger. Bigger plants need more soil to give their root system enough room. That is why you should transplant your plant to a larger pot at the start of the growth phase. You’ll find a grow guide on repotting outdoor cannabis plants here. Snug in their new pots, you give their leaves and roots full freedom to develop.

How cannabis grows from seedlings


This is also the stage for topping your plants if you wish to do so. In topping, you cut away the top end of the stem. This makes more energy available for lateral growth (branching out sideways, that is), allowing your plant to develop a greater number of buds.

Speaking of flower buds: even though the flowering stage follows the current growth stage, you can start to spot the first signs of male or female plants when your plant is about six weeks old. If you’re not working with feminized seeds, you’ll need to remove any male plants ASAP. If you don’t, you’ll get in trouble in the flowering stage, because males will pollinate females, making them produce new seeds instead of bigger flower buds. Read how to spot the differences between male, female, and hermaphrodite cannabis plants here.

Growths stage vegetative cannabis plant


Throughout the growth stage, your plant still needs 18 hours of light every day. It will also grow more thirsty as its root system matures. Keep watering copiously, but don’t overdo it. Check the soil moisture level to prevent the onset of fungi and rot. Beyond that, let your plant do the work. Make sure it stays comfortable, with enough-but-not-too-much water and nutrients, and enjoy watching how cannabis grows. Before long, the flowering stage will arrive.

4. Flowering Stage (7 to 9 weeks)

Although differences between strains are huge, after about two to four months, cannabis plants enter the flowering stage. At this point, female plants start to develop their calyxes or flower buds. The white ‘hairs’ on the buds are pistils, revealing your plant as feminine. These flower buds will soon be full of glistening trichomes. Trichomes are the tiny glands containing the resin that carries the most cannabinoids like THC and CBD. They also carry the terpenes that give your plant its unique scent, taste, and subtle effects. This is the fruit of your labour; the result you’ve been investing all your time and effort in.

How cannabis grows when flowering


If your plants are growing outside, this stage is initiated by the shortening of the days after the summer solstice has passed. At this stage, the cannabis plants only require 12 hours of light each day. As noted above, autoflowers don’t care about light; they’ll start flowering when they feel they’re ready. In the flowering stage, your weed plant needs plenty of water, as well as an ample supply of nutrients. Many growers add extra nutrition in the flowering phase. Be careful not to give too much, because that will ‘burn’ your leaves and harm your grow.

Flowering cannabis trichomes


If you’re not using feminized seeds, you need to remove all male plants at the onset of the flowering stage. If you don’t, males will fertilize your female plants and cause them to produce seeds instead of the big fat buds you’re after. As mentioned, you can see the early signs around six weeks into the plant’s life cycle, but the onset of flowering is your last chance to remove any males or hermaphrodites before they ruin your females.

Flowering cannabis full of trichomes

During flowering, watch out for fungi or pests harassing your plants. Rainy weather is something to watch out for in outdoor grows. For indoor growers, ventilation is key in preventing fungi and other unwelcome guests, as is a clean growing environment. It would be a shame if your harvest was to fail this close to the finish line.

How cannabis grows THC resin glands

One more tip: flowering weed plants smell of – you guessed it – weed. This is the stage at which nosy neighbours or ‘crop snatchers’ can become a problem. Take some time to think about how you will deal with these issues before you start growing.

Harvestable cannabis cola

How Cannabis Grows: After The Flowering Stage, It’s Harvest Time!

Many rookie growers find it hard to determine the moment at which their weed plant is ready to harvest. We know it’s difficult to stay patient and wait, but hang on – your crop yields will only get better! You can see when a plant is nearly ready to harvest once the trichomes go from transparent to milky white and opaque. The pistils of the flower are another tell-tale signal. By the time these pistils start to curl inwards towards the bud and turn golden brown, it’s almost harvest time.

Harvested weed drying


Once you start to harvest, you may think you’re all done, but wait! You’ll still need to trim your buds to remove any plant material without THC or CBD. In addition, harvested buds need to dry and then cure to attain perfect taste and potency. It’s a bit like good wine or cheese – it takes time. We will discuss these steps in separate blogs. For now, at least you know how cannabis grows. Fancy starting your very own grow adventure right now? Click the link below to find the ideal cannabis strain for your situation!

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