Cannabis Flowering Stage Guide

Growing your marijuana is a rewarding experience filled with frustrations and mishaps. But those things make cultivating cannabis plants a unique experience, whether you are a recreational user or a patient.

You might sometimes want to give up and head straight to your local dispensary. And then there are moments when your determination skyrockets, especially when you achieve milestones as a cannabis grower.

One example of such is when your crops enter the flowering stage. For growers, this milestone makes their goals clearer and helps them push forward despite their hardships.

But how exactly do you approach the flowering stage to ensure a bountiful harvest while minimizing potential setbacks?

Cannabis Plant Growth Cycle

To better understand the things that you need to do to move from the cannabis plant flowering stage to harvesting buds, it is helpful to learn a few things about the growth cycle of weed plants.

How long does a marijuana plant grow and live?

It can take anywhere between 10 and 32 weeks to grow a cannabis plant, from seed to harvesting its buds.

Of course, there are a few exceptions. All in all, the whole cycle can get shorter if you are starting with clones or with an autoflower seed.

The large discrepancy in the growth cycle of marijuana plants can be attributed largely to the vegetative stage and where you grow your crops.

If you are an indoor grower, you’ll have greater control of variables related to growth. Having this high degree of control allows you to dictate when your crops enter the flowering stage.

In contrast, an outdoor grower can only control a handful of variables, including light.

4 Growth Stages of Weed Plants

The growth cycle of a cannabis plant can be broken down into four stages: germination, seedling, vegetative, and flowering.

1. Germination stage

The germination stage is the shortest among the four, lasting anywhere from two to 10 days. However, there are some seeds that can take as many as two weeks to germinate.

Like many plant seeds, cannabis seeds are dry and hard. The colour of marijuana seeds can vary from light to dark brown.

To germinate cannabis seeds, you must moisten their hard exterior under dark conditions. At this point, the seeds don’t require nutrients.

You will know when your seeds have germinated when you see the emergence of its first leaves and a taproot.

During the germination stage, there is not much you can do but wait. Trying to hasten the process might result in damage to your seeds.

After germination, you can transfer your young cannabis plants to a small container with the substrate of your choice.

However, some growers who use autoflower seeds prefer to plant the seedlings directly in their final containers to minimize the hassle and stress of transplanting multiple times.

2. Seedling stage

The seedling stage refers to the next growth phase that happens two to three weeks after germination.

At this point, the root system of your seedling grows and develops. This is a critical development stage, and as such, you should avoid overwatering your crops.

You will also notice that your plants develop new leaves. During this time, you will see that their leaves look more like the familiar cannabis leaves with multiple fingers.

Like in the germination phase, your young plants do not require much water and nutrients. Your crops rely mostly on the nutrients available in the substrate. However, some growers add grow nutrients and root stimulators to facilitate faster growth and root development.

Seedlings do not require too much light. However, if you see signs of stretching, you can move your grow lights closer to your young cannabis plants.

3. Vegetative stage

The vegetative stage is where a cannabis plant achieves full growth, both in terms of height and width.

Usually, this growth stage lasts between three to 16 weeks.

Ideally, your plants should be placed in their final containers. This is also the time when most growers train their marijuana plants.

At this point, you will need to increase your plants’ water intake, paying attention not only to the main stalk but also to the surrounding area. Doing so will help the roots spread out.

Plants in the vegetative stage need lots of nitrogen as well as more light.

4. Flowering stage

The flowering stage is the growth phase, where your plants will produce buds and resins.

For photoperiod cannabis seeds, the flowering stage begins with a decrease in daylight hours. Autoflowering cannabis seeds, on the other hand, have the innate ability to enter the flowering stage without relying on the light cycle.

When a cannabis plant enters the flowering stage, its biochemistry changes, with that change, you will need to provide it with more phosphorus and decrease its nitrogen intake.

To coax a flowering cannabis plant will also need more intense light. It also helps to supplement your crops with carbon dioxide.

Transitioning from the Vegetative Stage to the Flowering Stage

If you are growing regular photoperiod cannabis seeds, you need to help your crops transition from the vegetative stage to the flowering stage.

With autoflowering strains, you don’t need to do that. As their name implies, these cannabis plants enter the flowering stage without any external prompt. Once they reach a certain height or age, they will automatically turn into flowering plants.

How do you know when your marijuana is ready for the flowering stage?

Many seasoned growers suggest that cannabis plants should enter the flowering stage after nine to 15 weeks after germination.

However, this is just a general rule. Aside from your crops’ age, there are a few factors that you might want to consider when you want your crops to turn into flowering cannabis plants.

1. Current height

One of the first things you should know is that flowering cannabis plants tend to double their height.

Ideally, you should flip your plants when they reach a height of one foot. If you let your crops grow beyond that, it is highly likely that they’ll grow four to five feet come harvest time.

The drawback of that situation is that your plants might grow too close to your grow lights or the ceiling of your grow room.

2. Root development

As much as possible, repot your weed plants while they are still in the vegetative growth stage.

This is important for two reasons. First, this gives you an opportunity to check their roots. Ideally, your crops should have excellent root development before the flowering stage begins.

Second, transferring your plants during the vegetative growth stage gives the roots the opportunity to recover from stress. Transplanting marijuana plants from one container to another can cause stress.

When your cannabis plant is stressed when leaving the vegetative growth stage, it will spend its resources on recovery instead of bud development.

3. Plant strength

A flowering weed plant should be strong enough to bear the weight of flowers.

Additionally, you should wait until there are more nodes and leaves on your plants. That is why most growers prefer to patiently wait for their plants to develop before coaxing them to enter the flowering stage.

4. Overall health

Before the cannabis flowering stage begins, your plants should be in the pink of health.

If your plant has been dealing with nutritional deficiencies and imbalances in humidity, temperature, and light, you should keep it in the vegetative growth stage to recover.

Once it enters the cannabis flowering stage, it might not be as productive compared to a healthy weed plant.

Starting the flowering cycle

Once you are certain that your plants are ready to enter the flowering stage, these are the things that you need to do.

1. Change the light cycle.

Plants that are still in the vegetative growth phase use darkness to repair themselves, taking advantage of all the energy they accumulate during the day.

During the flowering phase, your plants will use the hours of darkness to develop buds.

When you want to transition your plants from the veg state to the flowering stage, they will need to change the light cycle to a 12/12 scheme.

But aside from modifying the hours of light and darkness, you should also give your plants higher-intensity light.

If you are growing your weed plants indoors, make sure that your grow space is sealed tightly to prevent light leaks. Light leaks can make your plants focus on photosynthesis instead of bud production. Worse, light leaks can cause some of your plants to turn into hermaphrodites.

2. Maintain a stable temperature

Weed plants do not like too many variations in the temperature inside the grow room, especially when they are in the flowering stage.

As much as possible, try to maintain a stable temperature during the flowering stage.

Maintaining a stable temperature is essential during the flowering stage as it also helps regulate relative humidity.

As your plants mature and begin to flower, they will need lower humidity compared to when they were still in the veg stage. When the relative humidity is high, your plants might succumb to mould and mildew.

As a rule of thumb, try to keep the temperature around 70 degrees Fahrenheit.

3. Modify your plants’ nutritional intake

As your plants go from the veg state to the flowering stage, their nutritional needs will change.

During the vegetative phase, cannabis plants need fertilizers with higher nitrogen levels and little to no phosphorus content.

Once they move into the marijuana flowering stage, they will need a fertilizer with a different formulation. This formulation should contain less nitrogen and more phosphorus to help them in the development of flowers.

Potassium is another essential nutrient that flowering plants need. This nutrient plays a vital role in various functions, including moisture retention and cellular growth.

Ideally, you should switch to a fertilizer that supports blooming about a week or two after you modify the light cycle for your cannabis plants.

How to Determine the Sex of Your Cannabis Plants

Unless you are interested in breeding and producing cannabis seeds, it is a good idea to identify the sex of your plants before they reach the flowering stage.

Why it is important to identify the gender of your plants

Cannabis is a dioecious plant which simply means that there are male and female marijuana plants.

If you are growing these plants at home, it is highly likely that you are cultivating them for their flowers.

Now, when you buy regular cannabis seeds, there’s a strong chance that half of them are male and the rest are female.

If your goal is to harvest flowers, you will need to discard the male plants (as well as the hermaphrodites) to prevent them from pollinating your female plants.

When female plants are pollinated, they will focus their energies on seed production instead of flower production.

Essentially, you want to know the gender of your plants so that you can use your resources more efficiently and prevent pollination.

How to identify male plants

Weed plants can be gendered upon reaching adulthood, roughly after the first month of reaching the vegetative phase.

However, it is possible to determine the gender of your plants earlier, especially if you are an indoor grower.

To spot the male plants from your crops, the first area that you need to look at are the main stem nodes, especially the topmost portions where the sex characteristics show up first.

Like female plants, the males have sacs. However, in males, these sacs form into clusters that are shaped like bananas. Within these sacs is pollen.

These sacs can open up in a matter of days after they appear. And once these sacs open up, the pollen can disperse and fertilize your females.

This is why it is critical to identify the male plants as soon as possible.

How to identify female plants

Female plants have one to two white hairs called pistils that stick out from the top.

Sometimes, the pistils do not appear immediately during the pre-flowering stage. You might have to wait for a couple of days before they appear.

Females also produce stipules that also look like green hair. Although male plants can sometimes produce stipules, in females, these stipules can cross one another. The stipules in male plants rarely cross one another.

When you identify female plants, it’s a good idea to check on them after a few days, especially if your crops have been stressed.

Sometimes, the ones you identified as females may be hermies.

How to identify hermaphrodites

Hermaphrodites are cannabis plants that exhibit both male and female characteristics.

A cannabis plant can turn into a hermaphrodite after being subjected to stressful conditions like poor nutrition, temperature extremes, and excessive pruning.

There are also hermies that are genetically predisposed to be so.

Natural hermies are easier to spot because their sexual characteristics appear at the same time. However, hermies that developed their sexual characteristics due to stress are harder to identify because they produce fewer male flowers.

Either way, you have to cull hermies because they have sufficient pollen to fertilize female flowers.

Even if you are a breeder, you should not use pollen from hermaphrodites.

Marijuana Flowering Stage Week by Week

The cannabis flowering stage can be divided into two halves: the first flowering weeks and the late flowering stage.

To give you a fair idea of what to expect from your flowering cannabis, here is a week-by-week breakdown of the flowering period.

Flowering stage: weeks one to three

During the first few weeks of the flowering stage, you won’t notice too many differences in your cannabis plants.

During these three weeks, your plants will continue to grow. And as such, you need to ensure that you meet their nutritional needs and provide them with ample space to grow.

Week 1

The first week of the cannabis flowering stage is all about transition.

At this point, you will notice furious growth among your plants. It is not unusual for some strains to double their height during this period. Weed plants entering the flowering stage will grow more leaves and colas.

This growth spurt is necessary to support the development of buds.

To support your plants during this phase, you will need to provide them with the necessary nutrients. However, do not change their nutrition drastically.

According to experienced growers, it is best to wait until the actual flowering phase begins before changing fertilizers.

Week one is also the best time to start training your plants to maximize your yields.

Week 2

During the second week of the flowering stage, you will notice white pistils appearing on your females. These white hairlike structures will eventually transform into buds.

Some growers identify the sex of their plants during the second week because the differentiating characteristics usually appear at this point.

As much as possible, eliminate your males to prevent them from pollinating your female cannabis plants.

During this stage, it is essential to feed your plants appropriately. Be sure to check the product labels and suggested feeding schedule to increase bud production and prevent nutrient burn.

Week three

During the third week of the flowering phase, your plants should be noticeably bigger. However, your plants will slow down their growth and begin ramping up their flower production.

If you carefully inspect your plants, you will see flowers developing in the areas where the white hairs were previously seen.

Although your plants are deep into the bud production stage, you still won’t see the trichomes and resin glands. As such, your plants won’t emit a pungent scent.

Like in week two, you should make sure that your plants get the nutrients they need. This week is an opportune time to troubleshoot problems like underfeeding and nutrient burn.

Week 4

By the fourth week, your plants have stopped growing and turned their attention toward growing buds.

Although you might see a few white hairs here and there, it is more likely that you’ll see the buds have grown larger.

Week 5

During the fifth week, the buds should be noticeably larger. At this point, you may also have new buds growing from the main cola.

During this point of the flowering stage, you will notice that your plants are emitting a strong, pungent scent.

The fifth week is also the time when you will see changes in the colour of the pistils and trichomes. During this time, the pistils will grow darker while the trichomes become whiter.

Late flowering stage

The late flowering stage covers the last few weeks before harvest. On average, most strains are ready to harvest by the eighth week. However, there are some strains that may take longer than that to be ready for harvest.

During this period, your plants should have stopped growing. Instead, they will focus all of their energies on bud growth and development.

It is also normal to see some of the leaves, especially the ones located at the bottom, turn yellow.

However, if you notice yellowing leaves before the late flowering stage, you might be dealing either with light burn or nutrient issues. Deal with these as soon as you can to prevent problems later on.

Another issue that might arise during the late flowering stage is foxtailing. Foxtailing occurs when your grow room is too hot, or the light level is too much for your crops. Again, make the necessary adjustments as soon as you can.

The late flowering stage is all about maintenance. Do not change your feeding scheme. It won’t prevent yellowing leaves or increase bud production.

Preparing Cannabis Plants for Harvest

The late flowering stage is also the best time to prep your plants for harvest. Harvesting buds isn’t just about cutting the flowers off your plants. You need to make the necessary preparations to get the most out of your flowering cannabis.

Flushing your plants before harvesting

One of the essential tasks that you need to do before harvesting buds is flushing.

Flushing helps ensure that the flowers have a better aroma and flavour. But what exactly is flushing?

Flushing refers to the act of running water through the substrate. Running water through the substates removes excess nutrients and forces the plants to use up all the nutrients they’ve stored up.

Flushing is best done around two weeks before harvest.

Wean your plants off fertilizers two weeks before harvest.

Check your plants

Before harvesting flowers, your plants should be in good health.

A few weeks before harvest, check your flowering cannabis for signs of pest infestations, fungi, mould, and mildew.

This is also a good time to remove big and damaged leaves.

Knowing When to Harvest Buds

When it comes to harvesting cannabis flowers, timing is essential. You don’t want to harvest buds before they are ready or already overripe.

But how exactly do you know when to harvest the buds?

In general, the buds ripen around eight to 12 weeks into the flowering stage. Of course, there are some strains that are ready for harvest a little earlier than that.

But generally, you need to look at your flowering cannabis around that period.

Growers look at two things to ascertain whether the buds are ready for harvest.

Look at the pistils

First, check the colour of the pistils. If the pistils are still white in colour, you will need to wait a little longer. Your plants are not yet ready for harvest.

However, if the pistils have turned orange or brown in colour and you notice that these structures have curled inwards, that means that your crops are ready for harvest.

Look at the trichomes

The trichomes are the resin glands of cannabis. When the buds are ripe, they turn white, giving the plants a frosted look.

Some growers prefer to use the colour of the trichomes as an indicator of harvest readiness. Pistils may change their colour to orange or dark brown even if the plants are not yet ready for harvest. This happens because of changes in their growing environment.

Cannabis Flowering Stage Best Practices

All your hard work is about to come to an end. But this is not the time to slack off and become complacent.

Once your plants are in the flowering stage, you’ll need to make sure that they are ready for the final phase: harvesting.

Listed here are a few tips to help make sure that your flowering cannabis is in good condition during the flowering stage and beyond.

Ease your plants into the flowering stage gradually.

The first three weeks of the flowering stage are considered by most growers as the transition stage from the veg state to the marijuana flowering stage.

To prevent problems down the line, it is a good idea to be patient and make the transition from one growth phase to the other as carefully as you can.

One of the changes that you’ll need to make is shifting the light cycle to a 12/12 scheme.

Switch fertilizers

Another critical change during the flowering cycle that you need to facilitate is providing your plants with a new fertilizer formulation.

During the initial phase of the flowering stage, your plants continue to grow. This is necessary to support the development of buds.

Flowering cannabis needs more phosphorus and potassium, as well as sulphur and magnesium. At this point, you can stop giving your plants nitrogen.

Resist the urge to feed your flowering cannabis plant more fertilizer than it needs. Overfeeding can result in nutrient burn.

Trim leaves and branches carefully

Some growers defoliate the leaves of their plants. The idea behind this practice is that they want their plants to produce their buds.

However, practice caution when trimming leaves and branches off your plants. Remember, the leaves are necessary for photosynthesis. The energy that the leaves harness is vital for bud production.

If you must trim your plants, set your sights on dead leaves and branches.

By the final stretch of the flowering stage, you will see that the leaves turn brown. This indicates that your flowering cannabis plants have focused their energy on bud production.

Prevent light burn

Like overfeeding, excessive light intensity can cause more harm than good.

If you are growing cannabis indoors, it is a good practice to set your grow lights around one to three feet away from the top of your plants.

The actual distance between the top canopy of your plants and your grow lights will depend on the wattage of your lamps.

Once you make a shift in your light cycle scheme, make sure that you stick with that. Do not change anything or revert to the previous light cycle. Otherwise, this can cause problems like the appearance of hermies among your crops.

The hours of darkness and the hours of light should remain consistent throughout the flowering stage. If you have the resources, consider investing in a programmable timer.

You might also want to check your grow room for light leaks that give unwanted light during the hours of darkness.

Maintain a relative humidity of 45%

During the first few stages of the growth cycle, your plants need a relative humidity of 50%. Maintaining this humidity level is essential for their growth, as young plants require more moisture.

But once they enter the flowering stage, you need to cut back the relative humidity down to 45%. Excessive moisture in a grow room can lead to the proliferation of mould and mildew.

If you can, invest in a hygrometer and a dehumidifier to help maintain the appropriate relative humidity level.

Invest in an airflow system

As the buds ripen, the aroma in your grow room will become stronger.

To keep the pungent aroma at a low level and facilitate proper airflow, consider investing in an airflow system, preferably one with a carbon filter.

The Final Stretch

Once your plants enter the flowering stage, the finish line becomes more visible. If you follow this cannabis flowering stage guide, you’ll be able to reap the benefits of your hard work while avoiding some of the common pitfalls new growers experience.