The Life Cycle Of Marijuana Plants

Growing marijuana can be confusing, when you don’t know what to expect. You think you’re doing just fine until harvest comes around and you yield way less than you’d like.

As I have said, I love teaching others to grow marijuana. That’s why I’m going to teach you what to expect throughout a cannabis plant’s life. I will help you gain control of the situation through knowledge so that you can grow the best possible marijuana.

In addition to an overview of the marijuana plant lifecycle, I’ll also share some tips on storing seeds and harvesting. There are a few differences between growing indoors and outdoors, so I’ll discuss that as well. Keep reading to learn more about the various stages of cannabis growth.

Or, jump ahead to the section that interests you.

The Life Cycle Of Marijuana Plants

Growth cycle and plant stages

Your marijuana plant will go through a lot in its lifetime.

Unquestionably, there will be several major milestones. If you are familiar with them, you can better care for your plants. You’ll also likely notice health issues as they arise, instead of after it is too late.

When you know what the best-case scenario is, you’ll be able to recognize and fix problems. Be that as it may, sometimes you might run into a problem you just can’t fix.

For one reason or another, a plant just won’t grow, and nothing you do can change that. However, knowing what to expect never hurts.

See the difference a few weeks makes?

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Be prepared for every stage of your plant’s life by learning about the different needs and behaviors throughout their lifecycle.

Cannabis seeds

It all starts with the seed.

Cannabis uses sexual reproduction to create seeds and spread them. A single seed is produced by two parents and contains genes from both the female and male plants. There is an exception, however. That is when seeds are produced by a hermaphrodite plant, but that is a complex process at-home growers don’t need to worry about.

marijuana seedsMarijuana seeds

Beneath its waxy coat lies a tiny dehydrated plant (comprised of the root, stem, and two leaves), just waiting to be exposed to moisture and warmth. Metabolically, the plant slows down and enters a static state, essentially putting itself into suspended animation. This allows the seeds to remain viable for long periods, but not indefinitely.

Once the plant receives water and heat, it sprouts. Otherwise, it grows too old and dies. This is why you can’t keep seeds forever (although some seeds keep better and longer than others).

Next to the tiny plant, inside the seed, is a tiny store of calories to start the plant on its journey. This is known as the endosperm.

Cannabis seeds will lie dormant until they are exposed to water and light. The seeds themselves are fairly hardy, and should be able to survive well in a dark, cool place, given stable temperatures. A fridge or cellar is perfect.

Here’s why you need to protect your seeds:

They can die, meaning they never grow into a harvestable plant. You can keep this from happening by storing them carefully since extreme temperatures are the most likely way to damage seeds. A temperature below freezing can kill cannabis seeds.

Germinating seeds

When you’re ready to grow your plant, expose the seeds to light and moisture. That exposure will activate a series of hormones within the seed and kickstart the growth process.

Did you know?

A single root grows down and splits open the outer shell of your seed, then reaches downward into the soil in search of water and nutrients. At the same time (or just after), a green stalk will shoot upward, and two initial cotyledon leaves appear. 


  • cracks open
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This is when seeds start to vary as there are actually two different kinds of seeds. Cannabis plants are called cotyledons. This means they have two distinct leaves on their sprout, and they belong to the dicotyledonous group of plants. 

germinating weed seedsGerminating seeds

As a sprout, the cannabis plant has two meristems— one at the crown which is known as the “shoot meristem” and one at the root, known as the “root meristem.” The former will become the stem and foliage while the latter will become the taproot.

Cell division occurs in the meristem cells of the plant. This is the foundation of plant growth.

The meristem is important because:

The highest concentration of multiplying cells resides here. Of course, there are multiplying cells throughout the plant, but they are heavily located in the crown and the roots. In other words, this is where the majority of plant growth occurs.

Germinating plant growthPlant growth after germinating

Typically, as meristem cells mature, they will solidify into a single type of cell: that is, they will become buds, roots, leaves or stems, and will exclusively produce those cells. Once a meristem cell has begun producing roots, for example, it will no longer be able to reproduce leaves or stems.

But here’s what matters:

Meristem cells are essentially identical. It is only their location and the precise stimuli they are exposed to that make them react differently. This is an important distinction to keep in mind when cutting clones since the cells at the base of the cutting will become roots, and those at the top will grow into the rest of the plant.

You have to be careful, of course, but there’s a workaround if you mess up:

You could apply auxins like naphthaleneacetic acid to the plant. Auxins are rooting hormones which will help encourage root growth on new cuttings. That can help if your roots simply won’t grow.

But remember, sometimes your seeds won’t sprout.

All seeds are different, but, in general, cannabis seeds lose efficacy after a year or so. That being said, some could sprout even after several years.

Moisture and seeds

I can’t say this enough:

Moisture levels should be kept as low as possible when storing seeds. Moisture can allow fungus to grow or cause premature sprouting of the seeds, both of which are devastating if a grower has any intention of growing viable plants out of them.

“Over-watering is the biggest obstacle some growers face when germinating seeds and growing seedlings.”

Jorge Cervantes

When you do want to initiate sprouting, you’ll need moisture, but even then, be careful not to let the seeds absorb too much water, or molds and rot may become issues.

When you sprout marijuana seeds, moisture enters through micropyles. Micropyles are tiny porous openings. If they are misshapen or clogged with foreign material, it may be difficult to germinate your plants.

This is not a big problem though, because:

You can soak your seeds in a water bath. You can also scratch the surface of the seed using a process called scarification. To do this, nick the seed lightly with a sharp edge or use an abrasive surface.

Here’s the catch though:

You only want to do this if absolutely necessary for inducing germination. Seeds that require a great deal of extra effort to sprout could pass on their traits to future generations. It would be a shame to create extra work for yourself.

“Seeds do not need any extra hormones to germinate. Household water contains enough dissolved solids, food, to nourish seeds through their first few weeks of life.”

Jorge Cervantes

As the little plant hidden away inside the seed absorbs moisture, it will begin to swell and grow. Eventually, it will burst out of the shell, and leave behind its state of suspended animation. After that, it will require regular heat, water, and air. It will no longer survive in a dry environment.

Seedling stage

In the meantime, the seedling continues to grow breaking apart the seed coat that was protecting it. At the same time, the root systems at the base of the plant begin to develop, while leaves begin to spread out and grow out from the top of the plant.

seedling stageSeedling Stage

Soon, new leaves will grow, and the plant will enter its first true growth cycle. From there, the plant will continue to grow bigger and bigger until the buds are triggered to flower.

After about 3-7 days of initial growth, a healthy seed should have grown into a seedling. This stage begins when a plant starts to develop a stable root system and an initial growth of “true leaves,” that is, leaves which exhibit the same form and characteristics as mature cannabis leaves. We are not talking about the cotyledon leaves that pop up right after germination.


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Your plant can remain a seedling for a while, anywhere from 3-6 weeks. The duration depends primarily on environmental factors and the particular strain that you are cultivating.

You’ll always want to pay close attention to your plants, but be especially careful to do this in the early stages of growth. Pay attention to the speed at which the foliage develops.

As the plant begins to develop foliage and a stable root system, it will transition into the vegetative stage of growth. This is especially important if you are planning on transplanting. If you want to move your seedling to a new container or environment, now is the time to do it.

People who successfully grow do this during the seedling stage:

  • Maintain a temperature of 77 degrees
  • Maintain proper humidity
  • Limit the number of nutrients

Nutrients can burn the cannabis seedlings; if you must use them, use very little. You’ll need white light (18 hours per day) as soon as you see those cotyledons, as well a temperature between 68- 77 degrees and humidity of approximately 60%.

CFL lights are perfect for seedlings because they don’t produce a lot of heat. You can place the seedlings as close as 2 inches from the lights – giving them plenty of light. Need lights?

Vegetative stage

This is when your cannabis plant really comes into its own, producing the sort of big jagged leaves you’ve been waiting for. Your plant can produce more foliage because it can now absorb and process much more carbon dioxide and other nutrients.

vegetative stage cannabisVegetative stage

During the vegetative stage of growth, the roots will continue to expand, and the plant will grow taller. This is when people say you can “watch your plant grow.” A healthy cannabis plant can grow up to 2 inches in a single day!

The duration of the vegetative phase is controlled primarily by light exposure. If you are growing outdoors, this means it will depend on what part of the world you are in. For indoor growers, it means you can keep the plant in a vegetative state for as long as you please, but it normally lasts 1 to 2 months.

Vegetative stage

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A lot happens during the stage. To begin with, the plant essentially grows leaves and stalks. It also produces a solid structure that can support heavy buds. The plant grows taller and larger, with new layers of leaves being added. At this time, you should be able to notice the difference between cannabis varieties.

The temperature should be between 68- 77 degrees, with a humidity of around 50% to 70%, constant white light, (at least eighteen hours a day) and nitrogen-rich fertilizer as needed.  The stage lasts approximately 1 to 2 months.

This stage is fairly passive for the grower, but you should pay attention to your light exposure. We’ll have more on the relationship between light exposure and flowering in other articles.

Flowering stage

The last stage of the cannabis life cycle is the most important for growers (and everyone that gets to enjoy the harvest). The flowering stage begins after a period of reduced light exposure. It represents the period when a plant becomes sexually mature and ready to spread its genes. Both female and male plants have a flowering stage, but male cannabis plants usually mature earlier than the female plants, sometimes up to a couple weeks earlier.

Flowering stageFlowering Stage

When the plant reaches the flowering stage, it will begin to produce large quantities of sticky resin on the outsides of the leaves. The resin is centered on the reproductive parts of the plant, also known as “the buds.”

This resin contains the highest percentages of THC that you will find on the plant. To emphasize its importance, THC is the active ingredient most sought after by smokers and medicinal users.

The specific potency of your plant (the percentage of active ingredient in the resin) will be determined by the amount of time a plant has spent flowering. It also depends on whether or not the plant has been pollinated and fertilized.

Length of the the flowering stage

By now, you are likely eager to harvest the forming buds, but you’ll want to wait, and it may be a while. The length of the flowering stage can vary depending on what cannabis strain you’re working with and how much control you have over your growing environment.

There are, however, some standards:

Most cannabis strains have a flowering period that falls somewhere between 6-10 weeks, although, given the right strain and the right conditions, this could go on for even longer.

For practical purposes, you can split up the flowering stage into a couple different sections. First is the phase that occurs right after your plant finishes the vegetative stage. During this time, you may notice some bud development. Many growers like to call this the pre-flower stage.

However, most growers start the flowering period with a change in lighting. After changing the light cycle to 12 hours on and 12 hours off, the cannabis development rate increases dramatically, and the internodes become shorter so they can form the construction that will carry the cannabis flowers. An internode is located on the stem. It represents the area between two nodes where leaves will emerge.

During this time, the temperature should remain between 68- 77 degrees, with a humidity between 50% to 70%, a light cycle of 12 hours of orange-red lighting per day and a nitrogen-rich fertilizer as needed. You should start to see bud-like structures just after the pre-flowering phase that probably lasted around two weeks. They will continue to develop, but not as fast as before. You’ll also start to see early flowers.

temperature flowering stageTemperature flowering stage

When you notice buds developing, the cannabis is in bloom and will stop growing.

This is great because:

The plant will now invest everything into the growth of its buds, while also growing thicker and denser.  The buds are heavy, covered in resin and you can smell them. Some pistils turn brown, and some big leaves at the bottom turn yellow.

At this time, the temperature should remain between 68- 77 degrees, with a humidity of around 50%. There should be a light cycle of 12 hours of orange-red lighting per day. You can use a fertilizer with K (potassium) and P (phosphor) in normal amounts, but no more nitrogen!

Flowering stage

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About 10 days before the plant matures, you should stop fertilizing. You can identify maturity when the buds are dense, glimmering and smelly.

Until now, everything was green. However at this point, the pistils turn brown, the large leaves turn yellow in large numbers, the buds expand and gain weight, and the development of calyces slows down. Depending on the type of cannabis and on your taste, you can begin harvesting.  


Harvesting is not really part of the life cycle, but it is a crucial point in the life cycle of your marijuana plants. When you harvest determines the taste, smell, effects, and strength of your marijuana.

The best way to decide when to harvest is by looking at the pistils. The pistils are the little white hairs on the buds that slowly turn brown/red when your weed ripens.

Here is what to look for:

life cycle harvesting0-49% of the pistils are brown – Not ready yetlife cycle harvesting 250-70% of the pistils are brown – Ready for harvest, but it’s still a bit young. Light taste and mellow high. Maximum potency not yet achievedlife cycle harvesting 370-90% of the pistils are brown – Ready for harvest. Taste and effect are at their peak. You’ve reached maximum potencylife cycle harvesting 490-100% of the pistils brown – Almost too late to harvest. Taste is heavy, and the effect is narcotic. Harvest right away and don’t wait any longer

Indoor life cycle

So, how long is the entire growing process?

It depends on whether you are growing indoors or outdoors.

On average, the indoor life cycle takes around 3 months from seed to harvest. If you start with clones, it will take between 2 and 2.5 months. The life cycle length also depends on the flowering time of the strain you grow. Some strains take 7-8 weeks to flower while others take 9-10 weeks. There are even strains that take up to 15 weeks to finish flowering.

Indica dominant strains have a shorter flowering time than Sativa dominant strains

The flowering stage begins as soon as you change the light cycle from 18 hours of daily light to 12 hours of daily light. This is an easy way to know when your buds are ready for harvest. Although environmental factors in your grow room affect the flowering time, it’s not by more than 5 days. While flowering time may not be the most precise way to determine harvest time, it’s a good guideline.

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The vegetation time depends on the size you want your plants to grow before forcing them to flower. The more plants you place per square foot, the shorter the vegetation time. Above are some pictures of plants with their age.

It’s best to force your plants to flower when the leaf tips are touching each other. Seeing that the first 2 or 3 weeks of the flowering stage your plants will continue growing, make sure your plants don’t outgrow your grow room.

Outdoor life cycle

Want to grow outside instead?

Well, the life cycle of outdoor pants is a lot longer than the life cycle of indoor plants. This is because when growing outdoors, you cannot control the light cycle, so you have to let mother nature do her job. Depending on your local climate and the strain you grow, it will take 6 to 9 months from seed to harvest.

Marijuana plants react to the amount of light they receive. In the case of outdoors, the process can vary since the grower does not control the sun.

In August, when the days grow shorter, your plants ‘know’ winter is coming, so they start to flower. During the beginning of the flowering stage, the female plants get pollinated by the males so they can produce seeds to reproduce.

Outdoor mixed with malesFemales get pollinated when mixed with males

From the day your plants begin receiving less light, it will take 2 to 3 months before they are ready for harvest. Most strains will be ready in October or November. Indica strains have a shorter flowering period than sativa strains.

Don’t choose a long flowering strain if you live in a climate where winter starts early

The outdoor season starts when the last frost is over. Seedlings don’t like frost. To get a head start, you can germinate your marijuana seeds indoors to start with strong plants and place them outdoors when the frost is over.

To get the most out of a short growing season, try this pro tip:

Germinate your plants 2 months before it usually stops freezing. Once you believe the freezing temperatures have ended, set your plants outside, but don’t transplant them immediately. Keep them in a container for a month. That way, when the weather is too cold or too windy, you can easily place your plants indoors for a day.

30 day old marijuana plant30 days old – Could go outside

There is one exception to both the indoor and outdoor life cycle: autoflowering strains. These strains take 10 weeks from seed to harvest and are not sensitive to the light cycle.

Flowering for too long

Here’s the thing:

While you want your plants to flower for a good amount of time, it is definitely possible to let cannabis go for too long. In this over-mature phase, the cannabis plant loses medicinal value because it deteriorates.

Flowering too longFlowering too long – Harvest on time

What happens when you fail to harvest?

The cannabis plant stops producing calyces, the stem swells, the calyces stretch themselves, and the leaves become yellow and fall off.

Each phase of the cannabis growing process has its own specific environmental factors such as humidity percentage, fertilization, light cycle, and temperature. Keep all of these in check if you want a great harvest with dense ‘medical-grade’ buds.

To summarize:

Once you understand the cannabis lifecycle, it is easy to start growing marijuana like a pro. No more rookie mistakes like freezing your seeds or transplanting at the wrong time. Instead, you’ll be ready to try more advanced growing techniques and practice new skills.

Don’t worry, I go into much greater detail on other things you can do to improve and control the growth and health of your plants elsewhere on this blog.  In the meanwhile, sit back and watch your flowers grow.

Frequently asked questions

How much marijuana can I yield?   Your yield will vary based on many things. In addition to your level of experience, you must consider the strain, the conditions, and the amount of love you supply.

What happens when you stay in a veg or flower stage too long? Staying in the veg or flower stage too long can affect the quality of your buds. If in the veg stage, your buds will not get dense, in the flowering stage your plant may die before harvest.

Is it okay to harvest early? You can harvest marijuana whenever you want, but if you do it too early, your results may not be as potent.

If I start growing a plant outdoors in a pot, can I change my mind and bring it inside? Absolutely! Grow indoors or outdoors, but it’s best to choose one and stick with that. When you change the growing environment mid-lifecycle, it can shock the plant.

What should I do if a germinated seed isn’t thriving?  If your seed has germinated, but it won’t grow, it probably has less to do with the seed and more to do with the conditions.

Can you extend a cannabis plant’s lifecycle so that it can bloom annually? Cannabis is monocarpic. That means once it flowers it dies. You’ll only get one harvest out of a single plant; however, you could grow multiple plants in a single year.


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