When Does Cannabis Start Flowering Outdoors?

Ready to brush up on your outdoor cannabis cultivation skills? Understanding outdoor cannabis flowering is crucial for a fruitful harvest. Learn how light exposure, strain, and seed type intricately influence the flowering process. From the first signs of bloom to the final harvest, each factor plays a pivotal role in shaping your cannabis crop’s potential.

Whether you’re an experienced grower or just starting out, understanding the basics of outdoor cannabis flowering is key to growing a successful crop. With the right amount of daylight and nutrients, you can grow top-notch cannabis plants all season long!

From when to expect your cannabis plant to flower outside to understanding the fundamentals of light, temperature and water requirements, this article will guide you through everything you need to know about outdoor cannabis flowering.

What is meant by “weed season”?

“Weed season” is just a colloquial term referring to the cannabis growing season. After a long wait through winter, spring gives you the perfect opportunity to start cultivating your plants outdoors.

With temperatures warming up and daylight hours increasing, plants start to show signs of life, blooming into beautiful buds come harvest time. With all its nuances and complexities, weed season provides an opportunity for outdoor cannabis growers to nurture green thumbs and develop a newfound appreciation for nature’s wonders.

The exact start of the cannabis growing season depends on where exactly in the world you’re based. Generally, the growing season begins in the spring. Understanding how this cycle develops is key to understanding when your plants flower; a crucial moment.

The growth and development cycle of cannabis plants

Outdoor cannabis plants go through four distinct stages of development to reach their full potential: germination, seedling, vegetative, and flowering.

  • The germination stage is when the seed begins to sprout and the root system starts to form. This typically occurs within 3-10 days.
  • Next is the seedling stage, which usually lasts for 1-3 weeks and is when the plant starts to grow its first leaves and stems.
  • The vegetative stage is next and it lasts anywhere between 3-16 weeks (although 16 is rare). During this time, the plant will continue to grow in size and further develop its root system.
  • The flowering stage is last. It typically lasts 6-11 weeks in total.

The flowering stage itself is divided into sub-stages.

  • Flower initiation occurs during the first 3 weeks of flowering and involves pre-flowers developing in female plants as well as more growth of leaves and stems.
  • Mid-flowering takes place during weeks 4-5, where buds begin to form more visibly on female plants along with further growth of other features like fan leaves.
  • Late flowering or ripening happens from week 6 onwards with buds maturing fully on female plants ready for harvest.

The exact duration for the flower sub-stages depends on several factors, including strain type and seed type.

When does cannabis flower outdoors?

Cannabis plants typically flower outdoors between July and September in the Northern Hemisphere. The trigger for this is when days become shorter and there’s less sunlight. In Europe, outdoor cannabis cultivation largely depends on the region’s climate and latitude. Typically, cannabis plants begin to flower when daylight decreases to about 12 hours per day, which in many European regions occurs around late summer to early autumn.

However, this can vary based on specific geographic and climatic conditions. For instance, in Southern Europe, flowering might start earlier due to longer, sunnier days, whereas in Northern Europe, it could be delayed. Understanding local climate patterns is crucial for successful outdoor cultivation.

The days start getting shorter after the summer solstice which is usually on or around the 21st of June. This signals to the plant that winter is coming and it needs to get ready so it starts producing flowers. From a botanical standpoint a cannabis plant produces flowers to attract pollinators like bees and butterflies. These pollinators help transfer pollen from male flowers to female flowers, allowing the plant to reproduce and make seeds for future plants.

For cannabis growers, autumn is a great time of year as it marks the start of harvest season. However, with outdoor growing, you must also be aware of the changing weather conditions – too much or too little sunlight can have an effect on your yields. Plus, in the colder Northern European climates, there’s the threat of frost and harsh weather conditions.

How do different strains affect cannabis flowering outdoors?

Your cannabis strain will play a role in determining how long the flowering stage takes. So you’ll need to “budget” a certain number of weeks depending on whether you’re growing sativa, indica, or hybrid strains. All have the same vegetative stage duration (as it depends on the hours of daylight), but different flowering stage durations:

  • Sativa strains take approximately 9-12 weeks to flower.
  • Indica strains have a shorter flowering period lasting between 6-10 weeks.
  • Hybrid strains can take as little as 6 weeks are usually somewhere in between.

Whatever strain you’re looking for, we have some great options on our website. For sativa lovers, we have Trainwreck, powerful strain that flowers in 9-10 weeks, growing quite tall and producing pungent citrus flavours and an cerebral creative high.

Indica lovers might enjoy Critical Kush, with a short flowering time (6-8 weeks), a strong distinctive aroma, and a relaxing happy high.

How does seed type affect cannabis flowering outdoors?

The seed type you select will also play a role in flowering.

For instance, if you select an autoflowering seed, your seeds will automatically flower after a set period of usually about 3-5 weeks, regardless of light conditions. With their hardy and resilient nature, and “automated” flowering periods, they’re perfect for beginner growers. So for these strains, the hours of daylight outdoors doesn’t affect the onset of the flowering stage. However, summery weather conditions do still benefit the development of the plant as a whole, and the buds in particular.

Regular and feminized seeds, on the other hand, are photoperiodic in nature. This means their growth cycles are linked to changes in day length. Photoperiods require a little more management on the part of the grower to achieve the desired results. But, they leave room for more variance too meaning there’s more control over the final results.

Germinating photoperiods early means they’ll be in the vegetative state for longer, resulting in bigger plants. Germinating late could result in a shorter vegetative period. Photoperiods are a good option for experienced growers who want more control over the various growth stages, but they should time germination carefully to plan ahead for the entire cycle when growing outdoors.  

What role does light play in flowering outdoors?

Light is the most important element for outdoor cannabis growers. The length of daylight and even the quality of the light source work together to determine when a plant will begin flowering, as well as its biomass, flower number, growth cycle and chemical content.

When the days get shorter and the sun’s light decreases in intensity, it’s signal time for your plant to switch from vegetative growth to blooming! In fact, cannabis plants generally begin flowering when they have around 12 hours of consistent darkness followed by 12 hours of consistent daylight a day.

Are there any other factors that can affect when a cannabis plant flowers outdoors?

When it comes to outdoor cannabis cultivation, light isn’t the only factor you should consider when preparing your plants for flowering. Temperature, water and nutrition also play a critical role in controlling when your plants will bloom.

Let’s start with temperature. High temperatures can be a real buzzkill—especially if they’re above 30°C. At these levels, the cannabis plant won’t be able to carry out its normal processes which can lead to delayed flowering.

Second up is water—too little or too much can ruin your cannabis crop before it even starts blooming. It’s like a game of Goldilocks with your plants – not too hot and not too cold, just right!

If your buds go too long without getting quenched, then the stress may cause them to enter the flowering stage prematurely. This isn’t always a bad thing. Some growers do this intentionally. And there is some evidence that controlled draught can lead to a superior crop. But this should be handled carefully.

On the flip side, more water than necessary can suffocate them and prevent them from entering their flowering cycle altogether.

Then, there’s also nutrition—proper feeding is essential for any kind of healthy growth (and we all want healthy buds!). Feeding your plants with insufficient nutrients could trigger early flowering as a defence mechanism against resource depletion.

Outdoor cannabis flowering is usually an exciting and rewarding experience for any cannabis grower. While there are many factors that can influence when and how your plants will bloom, understanding the basics of light, temperature, water, and nutrition will help ensure a successful harvest season. With a little bit of care and attention to detail, you’ll be able to bring in some beautiful buds come harvest time!


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  • Author_profiles-WSS-Julien


    Meet Julien, an esteemed horticulturist turned cannabis connoisseur. Born in Toulouse, Julien pens insightful pieces to demystify cannabis cultivation, focusing on eco-friendly practices and strain genetics. He’s a proud advocate of responsible and enjoyable cannabis use, and highly committed to educating the community.
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