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Flowering (Bloom) Stage

what happens during the flowering stage?

The flowering stage directly follows the vegetative stage and is the last stage of growth of your cannabis plant when it develops its buds and flowers (usually a few weeks in). In photoperiod plants (plants that flower according to changes in the light cycle), flowering will begin once you reduce the period of light from 18-24 hours each day to around 12 hours or less each day.

In outdoor cannabis plants, they should naturally flower once the days begin to shorten. The plant will recognise that the hours of darkness have increased and signal to the plant to start the flowering process. This will depend on the climate and environment you are in and some strains can take longer to start flowering, as they may need a longer time frame of darkness each day to start the process. If you did want to start flowering early, you could always cover them over with a black sheet or anything else that will stimulate darkness.

For indoor growers, you are able to trigger the flowering process by manually change how long your lighting is on for each day. To start flowering, you will need to provide your plants with 12 hours of light and 12 hours of complete darkness each day.

The flowering stage will last for around 8 to 12 weeks. It is important to pay attention to your pants during this stage, as they will find it hard to recover from any problems, unlike in the vegetative stage, where they are a bit more forgiving.

For auto flowers, you do not need a change in the light schedule as they will flower automatically.

At the end of the first month in the flowering stage, your plant should start to develop its buds. It can also grow much taller during the first few weeks. The plant can be especially sensitive during this time, so be sure to handle it with care and monitor for any problems such as disease or plant damage. 

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As soon as the hours of uninterrupted darkness have increased, the plant will stop growing more stems and leaves and focus its attention on producing the buds you will then harvest. They will look like white pistils, covering the plant, as well as small flowerings on the newly formed buds.

Week 1 – Stretching Phase

The cannabis plant is likely to grow fast during the first week of the flowering stage and some can even double in height. This is when the plant will produce more stems and leaves, making itself stronger so it can take the weight of the new buds about to form.

Week 2 – White Pistils Emerge

If your plant is female, during the second week of the flowering stage you may begin to notice the white pistil forming on the plant. These look like very fine, wispy hairs, which will be formed into buds later in the process. During this time, it is a good idea to increase the amount of nutrients your plant is receiving. Phosphor and potassium are now better than nitrogen but be sure not to decrease the nitrogen amount too much or soon, as your plant still needs this to thrive. With the phosphor and potassium, increase these amounts slowly. If you are interested in trying the low stress training technique, now’s the time to start.

Week 3 – Buds Developing

The stretching and growing of your plant will slow down during the third week and the buds will slowly start being formed in the spots where the white pistils were located (these are known as budlets). Be sure to check you are using the correct level of nutrients and for any other problems with your plant, as anything going wrong at this stage will affect the quality or yield of your plant. It is normal for a few of the leaves at the bottom to start turning yellow, as they are receiving the least amount of light. If a lot of the leaves are becoming discoloured it could be a sing of nutrient burn (overfeeding).

Week 4 – Buds Growing Larger

Your plant will have stopped growing and the buds will be further developing and getting bigger each day. This will happen quickly, and you will still see the white pistils coming out from the buds. During this time, the plant is focused on growing these buds. You may start to notice the odour of your plant as this stage.

Be sure to keep watering, provide the right amount of nutrients and keep the plant stress free. Training during this stage is do-able but should be avoided if possible, as any stress to the plant now is likely to impair the growth of your buds. 

Week 5 – More Buds Form

During the fifth week, new buds will form all over the plant, getting bigger and fatter every day. The white pistil may turn a light brown colour and the odour of the plant will be much stronger.

Weeks 6 to 8 – Penultimate Stage

This is known as the late flowering stage and you will really notice your buds starting to ripen. Some strains may even be ready to harvest in these last few weeks, but the majority will be from the eighth week onwards.

During this period, you should stop or reduce the nutrients to your plant (known as flushing). If you continue to use the same nutrients as you did in the vegetative stage, this will revert the plant back to vegetative growth, or even start to produce seeds, which will then affect the quality of your plant. Giving the plant plain pH-balanced water, will help to dispose of the minerals in the soil and produce a much cleaner tasting bud, without a ‘chemical’ taste.

If the plant receives too much light or heat during these final stages, it could produce ‘foxtailing’, which is when buds start to form on already formed buds. With some strains this is usual but more commonly, it means your plant is likely to be stressed. To fix this, adjust anything that could be causing the issue, such as you plant being too close to the lights or increase air circulation in a hot room.

Week 8+ – Final Stage

The majority of cannabis strains will be ready to harvest at this stage. To check whether your plant is ready to harvest, you should look at the trichomes through a microscope. Trichomes are small hairs or outgrowths on the plant. Once they start turning from transparent to opaque and the colour changes to milky white or amber, the buds are ready to harvest. 

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