The Cannabis Plant Life Cycle: Every Stage From Seed to Harvest

The cannabis plant life cycle runs through four main stages: germination, rooting (the seedling stage), vegetative growth and flowering, with a short pre-flower phase in between. Cannabis is an annual, so most strains go from seed to the end of their life in four to ten months. Like every living thing, the plant grows through distinct stages, each with its own needs. 

Because it's an annual, the whole journey from seedling to harvest fits inside a single year and always unfolds in the same order. Broadly speaking, the cannabis life cycle breaks down like this:

1. Germination

2. Rooting (seedling)

3. Vegetative growth

4. Flowering

How long the whole cycle takes depends on whether the plant is a feminized photoperiod or an autoflower, whether you're growing from a clone or from seed, and how long the plant (or you) takes to cut back the light hours so it starts flowering. Here's a detailed look at each stage.

1. Germination stage

The first stage is seed germination, and it can take anywhere from 1 to 7 days. Seeds usually pop in 72 hours or less, but not always, and it can stretch out longer. In general, the bigger or older the seeds, the longer they take.

This is when the seed soaks up moisture from its surroundings and cracks its shell. You'll see it split open and a little root (the taproot) poke out, the start of a brand-new life. That's where your cannabis begins to grow.

If you germinate in paper towels or a glass of water, once the root is about 0.5 cm (¼ in) long you can move it into soil, and within a couple of days the seedling will pop up.

It's crucial that the growing medium isn't loaded with fertilizer, since too many nutrients can kill a cannabis seedling.

2. Rooting (seedling) stage: 

Once the seed is in the growing medium, the second stage, rooting, begins. It lasts about a week, although that depends on the strain and the growing conditions. 

This is when the first leaves come out. They're called cotyledons, and their job is to store food for the young plant. 

During this stage, and until about week 2-3 after germination, skip the fertilizer and give it plain water. The plant simply doesn't need nutrients this early, and too much can easily burn it. 

Keep in mind that a freshly germinated seed hasn't developed roots that can absorb nutrients yet, so patience is key here: let time and nature do their thing. Give your plants as much light as possible during this phase.

With clones, rooting requires high humidity, so cuttings go into a propagator (humidity dome) for a few days.

3. Vegetative stage: 

Now the plant kicks off its main growth phase. In veg, it focuses on growing: putting out leaves, shoots and stems. How long this lasts depends on the hours of light available. 

Outdoors, the plant starts flowering when the seasons change and the days get shorter, meaning at the end of summer as fall sets in.

In an indoor grow, you make that switch yourself, so you get to decide how long to keep them in veg.

Most growers veg for 1 month, a month and a half or 2 months. Going much longer isn't a great idea because the plant's height can get hard to control, and keep in mind a plant can double in size during flowering.

That's assuming the plant isn't meant to be a mother, meaning a plant you take clones from. If that's your plan, you can keep it in veg for years and prune it to keep its size in check.

As for feeding, it's best to start adding nutrients gradually, especially if you're growing in containers. Leafy plants love healthy, nutrient-rich soil or growing medium.

The nutrient plants need most at this stage is nitrogen, for chlorophyll production. But they also need phosphorus and potassium in smaller amounts. It's worth investing in the right fertilizers, or even, why not, making your own.

This is also the time to start using preventive pest products like diatomaceous earth, potassium soap (insecticidal soap) or neem oil.

As the plant grows, it'll also need more water. Young plants are best watered close to the stem, but as they get bigger, spread the water more widely so the root tips can soak it up more efficiently.

At this point, autoflowering strains may switch to flowering on their own after 2 or 3 weeks. Regular or feminized photoperiod strains only start flowering once the days get shorter (outdoors), as explained above, or once the grower cuts the light to 12 hours a day (indoors).

4. Pre-flower stage: 

When the photoperiod changes, meaning the light hours get shorter, the plant enters pre-flower.

This is one of the most important stages, because it's when the plant shows its sex and you find out whether it's male or female. Here you'll spot the first little white hairs (pistils), which tell you buds are on the way, or little sacs that mean pollen balls are coming and the plant is male, in which case it's best to cut it.

At this point the plant still needs the same nutrients as in veg, meaning high nitrogen, but you can start mixing in small amounts of high-phosphorus, high-potassium products to encourage flower development. 

5. Flowering stage: 

This last stage, flowering, breaks down into 4 phases, based on how the buds are developing.

Phase 1: Flower formation

This is the start of flowering, when the buds begin to form. At first they develop lengthwise, and once the initial stretch is over, the plant's vertical growth comes to a stop. This phase lasts about 2-3 weeks.

Phase 2: Bud bulking

Now the flowering plant's buds start to bulk up, growing wider. This phase lasts about a week, and together with the previous one, it's when cannabis takes up the most fertilizer, so it's time to bump up the dose.

Phase 3: Bud density

A few weeks before harvest, the plant focuses on adding weight to its buds, making them denser. At this point it needs less bloom fertilizer.

Phase 4: Ripening

Finally, in the last two weeks of the plant's life, all it does is ripen its buds. It's time to flush the roots (water with plain water to clear out leftover nutrients) and wait for the trichomes to hit their peak: fully formed and milky white.

As you can see, growing a cannabis plant is a fairly long process with several steps, but the end result is amazing. The most exciting part is watching that tiny seed or clone turn into a plant with incredible aroma and flavor. 

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