In this article, we’ll be talking about the life cycle of marijuana plants and the various stages of growth that cannabis goes through on its (relatively) short journey to adulthood and maturity.

There will be several major milestones your plant experiences. Knowing what these big changes are before you get there will help give you a better idea of what you can expect as you take care of your cannabis crop. It will also help you keep an eye on health issues as they arise.

With this knowledge, you’ll be better able to fix problems because you would know what the plant is supposed to be doing in a best case scenario. That being said, sometimes you might run into a problem you just can’t fix.

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For one reason or another, a plant just won’t grow, and nothing you do can change that. But let’s get started with the life cycle of the cannabis plant. It never hurts to know what to expect.

Every life stage that your plant will go through comes with its own challenges and difficulties. By informing yourself about the differences in needs and behaviors of your plant in the various stages you will be more prepared to deal with anything that comes along.

Cannabis seeds

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

Beneath the waxy coat of a seed hides a tiny dehydrated plant, just waiting to be exposed to moisture and warmth. Once gets 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).

Alongside the tiny plant, seeds also contain a store of calories to start the plant out on its journey. This is known as the endosperm.

Tip: make sure to download my free Grow Bible  for more information about cannabis life cycle

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. The most likely way to cause damage to seeds is low temperature: a temperature below freezing can kill cannabis seeds.

Related article: What are marijuana seeds

Germinating seeds

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

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 will appear.

Life cycle: Germinating

There are 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. Read the article How To Germinate Marijuana Seeds for more info.

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 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. These multiplying cells occur throughout the plant but are heavily concentrated in the crown and the roots, where the majority of the plant growth occurs.

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

Despite this, it’s important to remember that 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.

Sometimes growers apply auxins like naphthaleneacetic acid to the plant. Auxins are rooting hormones which will help encourage root growth when a new cutting is just beginning to grow.

Information about storing marijuana seeds is also relevant and important for growers. Cannabis seeds contain the endosperm, and the tiny plant (comprised of the root, stem, and two leaves). 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 of time, but not indefinitely.

Tip: make sure to download my free Grow Bible  for more information about germinating

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

Moisture sprouts seeds

Moisture levels should be kept as low as possible in storage. 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 the seeds in question.

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

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

One solution to this issue is to soak the plants in a water bath. Alternatively, you can scratch the surface of the seed (this process is called scarification). You can nick the seed lightly with a sharp edge or use an abrasive surface.

Only resort to these measures if absolutely necessary to help induce germination. Seeds that require a great deal of extra effort to sprout could pass on their traits to future generations, and it would be a shame to create extra work for yourself.

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 the state of suspended animation. At this point, it will require regular heat, water, and air. It will no longer survive in a dry environment.

Seedling stage

As the seedling continues to grow, it will continue to break apart the seed coat that was protecting it. The root systems at the base of the plant will begin to develop, and leaves will begin to spread out and grow at the top of the plant.

Soon new leaves will grow and the plant will enter it’s 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 plant should have grown into a seedling. This stage of growth is defined by a plant that has begun to develop a stable root system, as well as initial growth of “true leaves”, that is, leaves which exhibit the same form and characteristics as mature cannabis leaves. This does not refer to the cotyledon leaves that pop up right after germination.

Life cycle: Seedling stage

Your plant can remain a seedling for a broad range of time, anywhere from 3-6 weeks. The duration will depend 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.

The perfect heat during this stage is 77 degrees. Also, humidity is important, just like the time of germination. Nutrients can burn the cannabis seedlings so therefore few are necessary.

White light (18 hours per day) is needed from the instant you see the cotyledons, as well as some fertilizer with nitrogen (like Flower Power), 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 at 2 inches from the lights so they get enough light. Check these lights at this link.

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. The plant produces so much more foliage because it’s now capable of absorbing and processing a much higher amount of carbon dioxide and other nutrients.

During the vegetative stage of growth, the roots will continue to expand and the plant will grow taller. This is the point at which 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.

Life cycle: Vegetative stage

Just remember that you want to be careful about light exposure at this point. We’ll have more on the relationship between light exposure and flowering in other articles. Duration: 1 to 2 months.

In this phase, the cannabis plant essentially grows leaves and stalks. It quickly produces a solid structure so it can carry the heavy racemes. The cannabis grows taller and larger and new layers of leaves are added. At this time, you should be able to notice the difference between the cannabis varieties as the side branches reach their maximum.

Read the article Vegetative Stage For Indoor Marijuana Plants  for more info

The temperature should be between  68- 77 degrees, with dampness from 50% to 70%, perpetual white light of at least eighteen hours a day and additional fertilizer with nitrogen.

Flowering stage

The end stage for the cannabis plant is the one that’s most important for growers and cultivators (and eventual beneficiaries of the harvest). The flowering state occurs after reduced light exposure, and when a plant becomes sexually mature and ready to spread its genes around. Male cannabis plants usually mature earlier than the female plants, sometimes up to a couple weeks earlier.

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 colloquially as the buds.

These concentrations of resin contain the highest percentages of THC (tetrahydrocannabinol) that you will find on the plant, THC being 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.

Eventually, you’ll want to harvest the wealth of buds and deal with all of the processing that follows. That’s almost certainly why you’re growing your cannabis. For the time being, just understand that 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.

The flowering duration for most strains of cannabis falls somewhere between 6-10 weeks, although given the right strain and the right conditions, this could go on for even longer.

After changing the light cycle, 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 the distance on a stem between one node that defines a level of leaves to another node.

During this time, the temperature should remain between 68- 77 degrees, with dampness from 50% to 70%, a light cycle of 12 hours of orange-red lighting per day and fertilizer with nitrogen. The structure of the Cannabis budsshould be almost ready after the pre-flowering phase that probably lasted around two weeks. The development will keep increasing, but less rapidly and the earliest flowers/buds will appear.

Next you’ll begin to see the buds development. In this phase, the cannabis is in bloom and will stop growing. The plant invests everything in the growth of its buds and gets a thicker structure. 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 around 50%. There should be a light cycle of 12 hours of orange-red lighting per day and a lot of fertilizer with K (potassium) and P (phosphor) in normal amounts, but no more nitrogen!

Life cycle: Flowering stage

About 10 days before the plant become mature you should stop to fertilize the cannabis. You can identify maturity when the buds get an even thicker structure, are more resinous and more odoriferous.

Read the article Flowering Stage For Indoor Marijuana Plants  for more info

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 start to harvest now.

Harvesting

Harvesting is not really part of the life cycle, but it is a crucial point in the life cycle of your marijuana plants. The time of harvesting determines the taste, smell, effects and weight 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:

I wrote a mini harvesting guide with everything you need to know about harvesting. Learn how to harvest based on flowering time, pistils or trichomes and get the mini guide at this link. It is a must read guide for every marijuana grower!

Indoor life cycle

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 time 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 time 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. The environmental factors in your grow room also affect the flowering time, but not by more than 5 days. Flowering time is not the most precise way to determine harvest time, but it’s a good guideline.

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. Here 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. Keep in mind, 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

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.

Outdoor plants also react to the amount of light they receive. In August, when the days grow shorter, your plants ‘knows’ winter is coming, so it starts to flower. During the beginning of the flowering stage, the female plants get pollinated by the males so they can produce seeds to reproduce.

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. This way you can start with strong plants and place them outdoors when the frost is over.

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.

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. Read all there is to know about these strains in my article “What are autoflowering marijuana strains”

Flowering for too long

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 will stop to have medicinal value because it deteriorates.

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

Each phase in the growing process of the cannabis plant has its own specific environmental factors such as humidity percentage, fertilization, light cycle and temperature. All these factor indications should be followed in order if you want to get a good harvest and to guarantee a good medicinal use.

Don’t worry, we will go into much greater detail on the various steps you want to take to improve and control the growth and health of your plants.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible

Robert