Stages of Cannabis Plant Growth

Cannabis cultivation can be a challenge as there are a lot of different aspects of growing you’ll need to learn. Growing indoors varies widely from growing outdoors, and various factors determine the final results of a cannabis crop. CO2, nutrients, the pH balance of water, temperature, humidity, and more all play a vital role in cultivating quality cannabis.

Many places across the United States have legalized medical cannabis, and, similarly, a number of these places have also legalized small home grows for medical cannabis patients. For example, in the state of Oklahoma, medical cannabis patients are allowed to have six flowering plants and six plants in the vegetation stage.

Learning to cycle between these stages to keep your plants growing consistently is essential. When you first start growing, it can be confusing to figure out how long it all takes. Fortunately, it doesn’t have to be! Growing cannabis can be very therapeutic.

Weed plant stages from seed to harvest are split into a few main cycles. Let’s explore these cycles together and learn what they are and what to expect during each of them.

Weed Plant Stages: The Timeline

Understanding the various stages of cannabis plant growth is essential for a few reasons. You need to be able to recognize each of them so you can adequately provide your plants with the light, nutrients, and water that is appropriate for them throughout the phases of growth. The plants will also tell you when it’s best to prune, fertilize, and finally, harvest–which is what this is all for, after all!

On average, cannabis plants can take 3-8 months to grow a plant from seed to harvest. However, this can change significantly depending on whether or not the plant is grown indoors or outdoors, its light levels, and more.

Germination Stage (3-10 days)

Germination is the first stage of growing cannabis from seed and when seeds are introduced to water or soil. Some people germinate cannabis seeds by placing them in between wet paper towels inside a plastic bag until the seeds pop. They then transplant these seeds into small cups of soil. Others prefer not to risk handling the young seedlings and plant them directly into the soil.

Seeds take an average of 3 to 10 days to pop under the right lighting conditions. I start my seeds in small potters or solo cups as the small area for the root encourages quicker growth, which helps to sex the plants a little bit sooner.

Some people recommend putting cannabis seeds in water and only planting the ones that float since seeds that sink have cracked shells and are most likely not going to grow.

If you are germinating outdoors, you will want to make sure to have your plants in direct sunlight as the shade can cause issues with stretching of the young seedlings. Generally, after around ten days, if seeds are going to germinate, they have already done so. By day ten, you should have nice little plants popped up in your planters.

Seedling Stage (2-3 weeks)

In this stage, your plants will begin to sprout tiny versions of the famous fanned leaves we all recognize and love. More and more offshoots with additional leaves will begin to appear until the traditional six “fingers” are present on the stalks.

The plant is still very sensitive and requires a stable environment with proper light, humidity, and temperature as exposure to harsh conditions can quickly stunt its growth or kill the seedling. You should also watch out for mold and other diseases–since the plant is so small, it’s easy to overwater.

As the cannabis seedling grows, it establishes a more solid root system. Proper light levels are crucial–typically around 18 hours per day–to be sure it’s photosynthesizing properly. Seedlings can benefit from gentle breezes to strengthen their stems before adulthood, which helps them eventually grow and support larger nugs. Besides that, the seedlings don’t need much in the way of nutrients or fertilizer.

Proper care during the seedling stage creates a solid foundation for the vegetative and flowering stages, which later influence the plant’s health and yield. Additionally, you should start to see signs of sex, such as pre-flower hairs, though this isn’t always the case. You will soon have to sex the cannabis plants to determine males from females unless you are growing using feminized cannabis seeds.

Vegetative Stage (3-16 weeks)

By week three, you should be in full swing into the vegetative stage. The plants will be moving into larger pots, and their water needs will continue to grow rapidly. You can keep your plants in the vegetative stage for an average of 30 to 60 days, sometimes longer, depending on your skills as a grower.

During the vegetative stage, cannabis plants receive 16, 18, 20, and even 22 hours of light, depending on the growing method you’re using. When the vegetative cycle comes to an end, it is time to switch over to the flowering cycle. This is also an indicator that it is time to adjust your plant’s daily light intake, or DLI.

If you plan to utilize techniques like topping, the vegetative stage is the time to start. You can also begin using nutrients and fertilizers like nitrogen to help them grow larger and healthier.

Pre-Flowering Stage (1-2 weeks)

This is a very quick, rapid stage of weed plant growth. The pre-flowering stage of cannabis growth marks the transition from vegetative growth to the flowering phase.

During pre-flowering, the plant shows its first signs of sexual maturity. Small pre-flowers start forming at the nodes where the branches meet the main stem. These pre-flowers help growers identify the plant’s sex—male plants develop small pollen sacs, while female plants produce tiny, white pistils. Finding and removing the male plants is vital for people who would like to prevent the pollination cycle and focus on seedless, high-quality buds for consumption instead. You can learn more about cannabis plant anatomy here.

The plants will have a noticeable growth spurt, often called the “stretch.” This quick vertical growth prepares the plant for the upcoming flowering phase by creating more sites for bud development. You should adjust the light cycles to 12 hours of light and 12 hours of darkness if growing indoors, as this light schedule triggers the flowering response by tricking the plants into thinking it’s fall.

Nutrient needs also change during pre-flowering, so gradually increase phosphorus and potassium levels to support bud formation. Proper care and attention during this stage are crucial for maximizing your yield and getting healthy flower development in the next stage.

Flowering Stage (6-8 weeks)

The last and most critical portion of weed plant growth lies in the flowering stage. While in this phase, the plant pushes its energy toward growing dense, sticky buds filled with the ever-useful cannabinoids and terpenes. The buds start swelling significantly, and the pistils change color from white to orange or brown as they mature. The trichomes, which are the tiny crystal structures on the buds, become more prominent and shift from clear to milky white.

It’s absolutely vital to monitor these changes closely since they signal the best time for harvest.

Proper environmental control is crucial during this stage to ensure the best quality buds. Maintain the right humidity levels (40-50%) to prevent mold and mildew, and try to use consistent temperatures (68-77°F or 20-25°C) to support healthy development. You also need strong, consistent airflow to avoid bud rot.

Growers typically lower nitrogen levels in the nutrient mix and increase phosphorus and potassium to support the flower maturation. Some people choose to flush their weed plants with plain water in the last week or two before harvest to remove excess nutrients, which can help the flavor of the final product.

Harvest

Finally, you’ve made it! Your plants are healthy, happy, large, and ready to harvest for their bountiful buds.

To be sure your plants are truly ready for harvest, it’s important to follow a few simple steps and watch for some clear signs. One of the primary markers is the color of the trichomes, which should have changed from clear to milky white and, eventually, to amber. Harvesting when most trichomes are milky–with some turning amber–ensures maximum THC content and potency. If you want a more relaxed, sedative effect from your cannabis, waiting until a greater percentage of trichomes turn amber can increase the levels of CBN, known as the “sleepy cannabinoid.”

Another important indicator that it’s time to harvest is the color of the pistils, or the hair-like structures on the buds. The pistils slowly darken to orange, red, or brown as the plant matures. Harvesting when around 70-80% of the pistils have darkened is a common practice among growers.

Overall, the complete health of the plant, the swelling of the buds, and the reduction in white pistils signal that the plant is ready for harvest.

Post-Harvest: Drying and Curing

The hard work of growing is over, but what comes next? You’ll want to begin the process of drying and curing to preserve all of the cannabinoids and terpenes that are present in the buds.

Drying and curing cannabis plants are essential steps to preserve potency, enhance flavor, and ensure a smooth smoking experience. After harvesting, the plants are typically hung upside down in a dark, well-ventilated room with controlled temperature and humidity. The ideal conditions for drying are a temperature range of 60-70°F (15-21°C) and a humidity level of 45-55%. This process usually takes about 7-10 days. Proper drying allows the moisture to evaporate slowly from the buds, preventing mold and preserving the cannabinoid and terpene content.

Once the buds are adequately dried, they are ready for curing. Curing involves placing the dried buds in airtight glass jars, which are stored in a cool, dark place. The jars should be opened daily for the first couple of weeks to allow excess moisture to escape and fresh air to circulate. This process, known as burping, helps prevent mold and ensures an even cure. The curing stage can last from 2 weeks to several months, with longer cures often resulting in smoother, more flavorful cannabis. Proper curing enhances the overall quality of the buds, improving both the taste and the potency of the final product.

What Happens to Male Cannabis Plants?

Male cannabis plants play a crucial role in the reproductive cycle by producing pollen for female plants. Unlike female plants, which develop buds rich in cannabinoids, male plants grow pollen sacs that release pollen to fertilize the female flowers. In a natural or outdoor setting, this fertilization then creates seeds in the female buds.

However, for most growers focused on creating high-quality, seedless cannabis, male plants are usually unwanted. Their presence can lead to seeded buds, which are less potent and less ideal for consumption or reselling.

When male plants are identified during the pre-flowering stage, they are often removed from the growing area to prevent them from pollinating the female plants and then destroyed. This practice is particularly important in indoor grows or greenhouses, where the goal is to maximize the production of strong, seedless buds.

Although they lack cannabinoid-rich flowers, male plants do have their uses. They can be valuable for breeding programs aimed at developing new strains with specific traits. Additionally, some parts of male plants, such as leaves and stems, contain small amounts of cannabinoids that may be used for making concentrates or extracts.

Legal Considerations for Cannabis Cultivation in the USA

Every state has differing rules on the amount of cannabis you’re allowed to grow for consumption. In many states with medicinal programs, you’re allowed four plants per person. However, some may allow as many as six per person, and others don’t have growing allowances at all.

If you live in a state without legalized recreational (adult-use) or medicinal cannabis, you’re likely not allowed to grow plants at all, and doing so could lead to legal repercussions like fines or jail time. As a result, it’s absolutely vital to be aware of your state’s individual laws before starting your own cannabis grow.

Final Thoughts

Cannabis growing involves navigating a variety of factors to achieve a successful harvest, from understanding the various weed plant stages to managing environmental conditions and adhering to legal regulations. Each growth phase—from germination to flowering—requires attention to detail to ensure you’re rewarded with healthy, high-quality plants.

While growing cannabis can initially seem overwhelming, mastering it not only leads to a rewarding harvest but also offers therapeutic benefits for many growers. Working with plants has numerous mental and physical health benefits, and the knowledge you’ll gain during the experience only leads to more successful grows down the road. If you make a mistake or two, don’t fret–you’ll have a chance to try again, and you may even surprise yourself along the way.

Frequently Asked Questions

How do I know if my plants are overwatered?

Your weed plants may be overwatered if they are showing signs like drooping leaves, yellowing foliage, and a general wilted appearance. This may be accompanied by slowed growth and soggy, compacted soil.

How many hours of light are required for growing cannabis?

Weed plants typically require 18 hours of light per day during the vegetative stage and 12 hours of light per day during the flowering stage.

Can you speed up the germination process of cannabis?

Yes, you can speed up the process by soaking the seeds in water for 12-24 hours before planting. You can also try using the paper towel method in a warm, dark environment to encourage faster sprouting.

This article was originally published on July 7, 2021, and updated on July 11, 2024.