Stages of the Cannabis Plant Growth Cycle

Like all living things, the cannabis plant goes through various stages in their growth cycle. It’s important that growers know and understand these stages as the plant will need different things along the line. 

The different stages can call for varying amounts of light, water and nutrients. The stages will also help a grower determine when you can train or prune your plant. Establishing the sex of the plant and maintaining health rely on these stages too.

How Long Does Cannabis Grow For?

It’s hard to pinpoint a time frame for cannabis growth, as numerous factors can affect the growth of your plant. Generally speaking though, cannabis growth takes anywhere between 14-32 weeks, or about 4-8 months – from seed to harvest. 

The biggest variability in the growth of cannabis usually takes place during the vegetative stage – here, if you’re an indoor grower, you can force the plant to flower after just a few weeks or after several weeks depending on your preference for plant size. Growing outdoors, on the other hand, the seasons control your growth to a large extent – where a plant only naturally starts flowering in autumn. Buds usually develop in the final 8-11 weeks of growth. 

The Cannabis Plant Growth Cycle

The growth cycle of cannabis can be broken down into four main stages from seed to harvest: 

• Germination (5-10 days)
• Seedling (2-3 weeks)
• Vegetative (3-16 weeks)
• Flowering (8-11 weeks)

Germination (5-10 days)

Light cycle: 18 hours of light 

A cannabis plant begins with a seed. A seed is dormant and requires water to bring it to life. 

A sign of the quality of a seed can come from colour and texture. Your seed should feel hard and dry, with a light to dark brown colour. Underdeveloped seeds are often squishy and green/white in colour and probably won’t germinate. 

A test you can perform yourself to test your seed is to squeeze it between your thumb and forefinger. If it’s hard and strong – plant it! But if it feels fragile or you crush it – you have your answer and that seed may not be the best option. 

To start growing, you need to germinate your seed. This can take anywhere from 48 hours to 10 days. 

Once your seed has popped and you see that tap root, the seed is ready to be planted! The taproot will grow downwards in search of water, while the seedling grows upwards in search of light. Two round leaves, called cotyledons, will grow out from the stem as the plant pops from the seed. These are vital in absorbing light and helping the plant grow during the first few days.

As the plant grows, the roots will give the plant a strong base and will allow support for the first iconic fan leaves. Once you reach this point, your cannabis plant becomes a seedling. 

Seedling (2-3 weeks) 

Light cycle: 18 hours of light 

As your plant enters the seedling stage, you will notice more of the iconic fan leaves developing. Initially, this process begins with just one ridged fan leaf blade. However, as more growth appears, the leaves grow more blades – from 1, to 3, to 5 and commonly ending at 7. Mature plants will have 5-7 blades per leaf but can extend to 9 or even 12 in some cases. 

Your plant will be considered a seedling until they are regularly producing the full 5-7 blades per fan leaf. They should also be a vibrant green colour if they are healthy. Overwatering is a factor to be cautious about at this stage as roots are small and can easily be overwhelmed. 

Your plant is also susceptible to diseases and mould. These can be avoided by keeping your environment clean and managing humidity as best as you can. 

Vegetative (3-16 weeks) 

Light cycle: 18 hours of light 

The vegetative stage is the point where your plant begins to truly take off. Here, you may have transplanted into a bigger pot to allow for more root growth (which is a factor to consider in determining the size of your plant). Here you can also start training your plant by topping or using a method known as Low-Stress Training (LST). 

The spacing between your nodes will largely be determined by the type of cannabis you’re growing. Indica plants are commonly short and dense, while sativas are taller with more open growth. 

As your plant develops, you’ll want to be mindful of watering and gradually increase it. Young plants will want water closer to the stalk where their roots are, but bigger roots will grow outwards so you’ll have to water further away from the stalk too – allowing the roots to stretch outwards for water and continue to grow. 

A plant in the vegetative stage thrives in healthy soil with enough nutrients. They commonly require more nitrogen at this stage. 

Flowering (8-11 weeks) 

Light cycle: 12 hours of light 

The flowering stage is the final stage in your plant’s growth process. This occurs naturally when a plant receives less than 12 hours of sunlight as summer days shorten, or when an indoor light schedule is shortened. Here you will see the famous cannabis buds begin to develop. 

You will want to keep an eye on the sex of your plant at this stage as well to remove any unwanted males. You should notice these developments in sex just a couple of weeks into this stage. It is vital to remove the males (if any) before they pollinate the females. 

There are a variety of changes to keep in mind when your plant moves from the vegetative to the flowering stage: 

•  Once in flower, the plant shouldn’t be pruned after more than 3 weeks in this stage. This can upset the hormones and stunt the plant’s growth. 
• You should try trellis the plant or support it in another way as the buds become heavy as they grow. 
• Consider a nutrient of sorts to assist with the blooming process. 

What week of flowering shows the most bud growth? 

The biggest developments will come in the final weeks of flowering – usually around weeks 6-7. Budding seems slow at first, and also slow again during the end of flowering when buds are fully formed. 

Once our buds have matured fully – it’s finally time to harvest! You’ll want a strong magnifying glass to help you observe the trichomes. These trichomes develop in colour which allows you to determine the development of the plant and decide your ideal time to harvest. When it’s almost time to harvest, check out our Harvesting 101 article to help you through it.

Knowing the cannabis plant growth cycle is vital for new and experienced growers, so make sure you know what you’re looking at!