Content updated in August 2023
In this article, you will learn about the Cannabis plant life cycle, divided into stages week by week. You will find information about the plant’s growth at each stage, some of the plant’s basic needs, and what to watch out for! Learn how to grow weed from seed to harvest!
Table of contents
- Storing your Cannabis seeds
- Cannabis seed germination (lasts about 3 to 10 days)
- Cannabis seedling stage (lasts about 2 to 3 weeks)
- Vegetative stage (lasts about 3 to 16 weeks)
- Flowering stage (lasts about 8 to 11 weeks)
- When to harvest?
Cannabis growth is divided into seed germination, seedling, vegetative, and flowering stages. Each of these stages has its own environmental and nutritional needs, even different photoperiods. Learn all about the growth stages of the cannabis “weed” plant.
Storing your Cannabis seeds
This is how the life of a Cannabis plant begins. A viable seed looks brown with some stripes, is dry, and feels hard. If the seed feels weak or is white or light green, it’s probably an undeveloped seed that won’t produce a healthy plant.
Keep your cannabis seeds in a dark, cold place, for example, in the fridge inside a plastic bag for better conservation. When the time of germination comes, get your seed out at ambient temperature. You can better your germination chances by putting your seed no more than 12 hours in a glass of water; if it floats it’s probably not viable, although it may germinate anyway. If the seed sinks, it’s probably because it’s viable and full of life, ready for germination. Don’t let seeds in the water for much longer, as the seed needs to breathe oxygen and it may drown and die.
Cannabis seed germination (lasts about 3 to 10 days)
For germinating, Cannabis seeds need warm temperatures, humidity, air, and water. Place your seeds in a dark, warm, and humid place, for example between two plates in a damped napkin.
When the seed opens up and shows the first white taproot, it’s time to place it in a small pot, in its next growing medium (soil, coco, etc.). This root begins to develop and eventually, the plant forms the first two oval leaves, called cotyledons. Now it’s a seedling!
Cannabis Seedling stage (lasts about 2 to 3 weeks)
Factors that lead to the healthy growth of Cannabis seedlings
- Warm temperature, about 71.6 to 78.8°F (22° – 26º C )
- Relative humidity: about 65 – 80%.
- Low light intensity, blue spectrum preferred
- Adequate light distance (hand test) depending on the light source
- Light/Photoperiod: 18 hours of light / 6 hours of darkness
- Nutrition: a low dosage of nutrients for the beginning then increasing
- Small pot size: After germination, you should place your seed/seedling in a small pot or tray with drainage for better results
- Watering: Water your seedlings with a sprayer to avoid overwatering
- pH levels: between 5.5 and 6.5
This is how the seedling stage begins: when the seed opens, the first pair of small round leaves that appear, are called “cotyledons”. After that, the small Cannabis plant starts to produce serrated leaves, not the characteristic digitated leaves, only single serrated leaflets. As the seedling grows, new leaves develop with more leaflets until the plant produces digitated leaves with serrated borders we can all identify as Cannabis fan leaves. When these leaves appear, the plant enters into the vegetative stage. This process can take up to three weeks.
PH: Alicia M
Cannabis seedlings’ growing conditions
Cannabis seedlings like relatively humid conditions. Temperatures should remain warm and lighting should be placed near the plants and moved up as they grow. Finally, these baby plants require only small amounts of nutrients and their needs will increase as the plant gets larger and stronger.
Always check lighting and air circulation, keep watering to a minimum, and keep them in a small pot or tray for a few days rather than planting them in their final container. This will allow the root system to develop more easily and vigorously, and there is less risk of the small plant getting too much water and drowning. Make sure your seedlings get enough light, otherwise, they’ll grow very tall and weak, have few leaves, and have a stretched white stem.
Cannabis vegetative stage (Lasts about 3 to 16 weeks)
pics week by week
Factors that lead to healthy growth of Cannabis in the vegetative stage
- Warm temperature, about 22 – 26º C (80.6 to 78.8°F)
- Relative humidity: about 40-60%
- Increased light intensity / blue spectrum
- Adequate light distance according to the light manufacturer’s instructions
- Good airflow, exhaust system, and CO2 intake
- Light/Photoperiod: 18 hours of light / 6 hours of uninterrupted darkness
- Nutrition plan: Apply nutrients as needed – set a nutrient schedule and follow it
- Bigger pot size: After germination, place your seed/seedlings in a small pot, cup, or tray with drainage for better results. Transplant the plant as needed to avoid poor root development (rootbound)
- Watering: Water your plant regularly, avoid overwatering, and make sure the pot has good drainage
- pH levels: between 5.5 to 6.5
In the vegetative stage, a healthy Cannabis plant grows in height and size as much as it can under the given conditions. The plant now grows only leaves and stems. The plant may show solitary flowers, also called “preflowers”, which show sex (male or female). Inflorescences are groups of solitary flowers, also called “buds”. Buds will not begin to form until the days get shorter, in Autumn, or when the photoperiod is changed to 12/12 for most cultivars.
How long does the vegetative stage last?
Most growers let their indoor plants vegetate for 3-8 weeks, depending on the desired plant size. Cannabis plants are capable of flowering starting in the 3rd or 4th week of the vegetative stage (depending on the strain or cultivar), but these plants will probably be smaller. If you give your plants more time for the vegetative stage, the plants will grow bigger and are more likely to produce higher yields. Indoors, you will need to change the lighting timer to a 12/12 hour schedule to trigger the flowering phase (for most cultivars). In the 6th week after germination, some Cannabis plants are able to show their sex by growing solitary flowers or “preflowers”.
Male, female or hermie?
At this point, you should know (soon) if your plants are male, female, or hermaphrodite. If you are growing with the intention of harvesting Marijuana buds (not seeds), you should only grow female plants and kill the male and hermie plants ASAP. Male and hermaphrodite plants will soon start pollinating the female plants and you’ll end up with lots of seeds and very few buds. As said before, only female plants produce buds, male plants don’t and hermaphrodite buds are not so good. If you want to produce seeds or keep pollen, you can keep the male plants for that intent. Hermaphrodites are not desirable as their descendants will probably be hermaphrodites too.
Flowering stage (lasts about 8 to 11 weeks) – Pictures week by week
Factors that lead to the healthy growth of Flowering Cannabis plants
- Warm temperature, about 64.4 to 78.8°F (18 – 26º C)
- Relative humidity: around 40-50%.
- Higher light intensity, red spectrum preferred
- Adequate light distance: hand test
- Light/Photoperiod: 12 hours of light / 12 hours of darkness.
- Nutrition: a higher dosage of flowering nutrients
- Bigger pot size: Transplant to its final pot before starting the flowering stage
- Watering: Water as needed
- pH levels: between 5.5 and 6.5
Flowering stage indoors
To enter the flowering stage in indoor crops, the photoperiod must be changed to 12 hours of light / 12 hours of darkness schedule.
It’s extremely important NOT TO INTERRUPT the hours of darkness (lights off) so that the plant begins to bloom. If this dark period is interrupted, the plant gets “confused” and flowering may be delayed or worse, the plant may revegetate (go back to veg stage) or start producing hermaphrodite flowers. You definitely don’t want that to happen!
Flowering stage outdoors
Growing outdoors, plants will start the flowering stage when the days grow shorter, usually when Autumn is coming.
Autoflowering strains don’t need a photoperiod change to start flowering, their vegetative stage lasts around 4 weeks and then it changes stages automatically.
How long does the flowering stage last?
The duration of the flowering stage varies among different strains.
The flowering stage usually goes from 8 to 11 weeks, depending on the strain. It’s usually divided into weeks or three stages. The flowering period for “Indica” labeled strains is typically around 8 weeks, but it may take up to 10 weeks. “Sativa” labeled strains may take up to 10-12 weeks. Typically, hybrid strains will take up to 6-10 weeks to fully develop.
Flowering initiation – week 1-3 of the flowering stage
From weeks 1-3 of the flowering stage, plants stretch and grow in size and height. Plants stretch and double their size in this phase. The female Cannabis plant starts blooming by producing solitary flowers, also called “preflowers”, their pistil parts or “stigmas” sticking out look like “a pair of white hairs”.
Towards the end of the third week of flowering, the plant starts growing lots of solitary flowers and starts forming its bud sites in the plant nodes (where the main stem and the branches meet). Look for clusters of female solitary flowers or preflowers.
Mid-Flowering – week 4-5 of the flowering stage
From weeks 4-5 of the flowering stage, plants stop growing in size and start growing, fattening their buds and darkening their pistils. It’s important to keep a good feeding schedule in order to fatten the buds and help the plant grow strong aromatic components.
Late flowering / Ripening – week 6 to harvest
In the last few weeks, buds gain the most weight and flowers produce the highest amounts of cannabinoids, such as THC and CBD among others. Flowers are sticky to the touch and can be very smelly. You are very close to reaching your goal of harvesting.
In this stage of the Cannabis plant, pistils or stigmas may show white, cream, and brown colors. They also start curling inwards and buds get covered in trichomes. Similarly, trichomes also change colors and you should pay close attention to these changes because they are one of the best clues for knowing when is the best time for harvesting.
Remember you may need to do flushing prior to harvesting, so calculate your times in advance!
Flush for better results!
Flushing a Cannabis plant is basically running a lot of water through its growing medium (soil, for example) to get rid of the excess salt and mineral nutrients. It is recommended when there is an excess in fertilization.
Flushing involves watering your plants with only water, no nutrients added to “flush” all the salt excess from the roots. It may be done one or two weeks before harvesting (in soil) and in one day, two, or more, depending on your feeding schedule and crop size. During this period between flushing and harvesting, plants use most of the nutrients they’ve been building up and the result is said to be a much tastier and aromatic weed. If there is excess fertilization and you don’t flush, those buds may have a bad and strong flavor and smell and may feel harsh on your throat when smoked.
Even though lots of fertilizer companies recommend flushing plants for two weeks before harvesting, many growers nowadays choose to avoid flushing altogether and still have good results. It’s a matter of personal choice and one must evaluate the growing conditions, the nutrient schedule, and the final results. For organic growing without excess fertilization, flushing is not necessary. Bear in mind that the plant produces most of its cannabinoids in the last two weeks of flowering and flowers grow in size in that time as well. Flushing in excess or too early in flowering may lead to smaller and less potent cannabis buds.
Set reminders with the Grow with Jane app to start monitoring trichomes and pistil changes around weeks 6-7 with a hand lens, magnifying glass, or loupe to determine the best moment for harvesting.
For more information and growing tips on the Flowering stage of Cannabis plants, read our full article.
When to harvest a Cannabis plant (Week 8+)
Around week 8 of the flowering stage, buds will start fattening quickly. You will see that trichomes and pistils or stigmas are maturing and changing colors. Usually, when trichomes turn from transparent to a milky/whiteish color (and maybe 5-10% of them turn amber), your plant is ready for harvesting. It’s up to each grower at the harvesting moment, depending on the effects and flavors desired. Some cultivars may take 12 weeks or even more to complete the flowering stage.
We hope this guide helps you understand the Cannabis plant’s stages and life cycle. Now you know how much time each stage takes and what to expect.
Read the following article to learn how and when to harvest
Read the following article to learn exactly when to harvest your flowering plants, how to tell if they are ready by looking at trichomes and pistils, how to dry and cure your buds, and more! All are explained in a simple way, with pics and a Step-by-step harvesting guide.
Remember to download and try our Cannabis growing journal app, Grow with Jane! You’ll find lots of tools for planning and tracking your Cannabis crop through its stages, calculators, reminders, photos, and much more coming soon! And it’s free!!