For most growers, flowering is the most exciting time of the grow! All the work of growing cannabis finally becomes visible and shows up in resinous buds. Nevertheless, flowering is a phase in the life cycle of your cannabis plant that requires special attention. The flowering phase of cannabis not only marks the transition of your plant from the vegetative stage to the production of buds, but is also crucial for a bountiful harvest.
In this blog post, we will explain to you what exactly the flowering phase hemp is and how to recognize that hemp is in flower. We will also look at the special care requirements of hemp plants during this phase and give you valuable tips for flowering.
If you own a Bonsanto Growbox we recommend that you follow our Bonsanto growing instructions. There you will learn how to grow in our grow boxes. Since all Bonsanto Grow components are perfectly coordinated with each other and thus provide you with an ideal growing environment for your cannabis, you can completely dispense with the use of measuring devices for Bonsanto Grow!
Table of contents
What is the flowering phase?
The flowering phase of hemp refers to the period in the growth cycle of the hemp plant when the plant forms flowers. The phase follows the vegetative growth phase and takes place before harvest. Flowering is a crucial phase for growers, as the highest concentrations of therapeutically active substances, such as cannabinoids, tetrahydrocannabinol (THC) and cannabidiol (CBD), are found in the emerging flowers.
Instead of focusing on the formation of leaves and stems, cannabis puts energy into the production of flowers during the flowering phase. In addition to the production of flowers, the formation of resinous trichome glands also takes place. The flowering phase cannabis usually begins when the daylight hours are reduced (approximately to 12 hours of light and 12 hours of darkness).
You should know that cannabis is distinguished between female and male cannabis plants and only the female plants produce the so-called buds.
When does the flowering phase hemp?
When the flowering phase of your cannabis plant begins depends on whether you are growing indoors or outdoors. Outdoors, cannabis goes into flowering when the days get shorter, such as in the fall. When growing indoors, you can specifically send your plant into flowering by reducing the exposure from approximately 18 hours of light to 12 hours of light per day, as mentioned earlier. Autoflowers are an exception. These cannabis plants will flower on their own, regardless of the daylight hours.
How to recognize the flowering phase of hemp?
You can recognize the flowering phase of hemp by different signs. The first sign of the beginning of the flowering phase are the so-called pre-blooms. These small, hairy structures appear at the nodes of the plant where the main styles meet branches. In female plants, these preblooms look like tiny, hairy buds, often with one or two white hairs called pistils. In male plants, they are more spherical and contain no hairs.
A clear sign of the flowering phase are the pistils, which are white or cream colored and protrude from the preliminary flowers. These pistils are part of the female reproductive organ and capture the pollen of the male plants. During the flowering phase, they can change color from white to brown or red.
After the pistils develop, the actual flowering of your plants begins. The preliminary flowers become larger and denser and begin to form cannabis flowers or "buds". These are often sticky and aromatic due to the resin containing cannabinoids and terpenes.
In addition, the vertical growth of your plant slows down considerably during flowering, as energy is concentrated on flower formation.
How long is the flowering phase of hemp?
The duration of the flowering phase may vary depending on the variety and environmental conditions. However, in general, the flowering phase lasts between 5 and 10 weeks.
You should note that indica-dominant cannabis strains tend to have a shorter flowering time, while sativa-dominant strains are in flower for longer. As mentioned earlier, environmental factors also play a role. Hemp plants that you grow in ideal conditions will flower faster, while factors such as poor lighting, temperature fluctuations, nutrient deficiencies, or disease can extend the flowering time.
When the flowering phase of your cannabis plant is over and you should start harvesting, you can determine by the color of the trichomes and resin glands on the flowers.
When ends the flowering phase hemp?
The flowering phase of your cannabis ends when your plant is ready for harvest. The resin glands or trichomes of your plant are the indicator of when harvesting can take place. Use a magnifying glass to check if the trichomes have already taken on a milky and amber appearance - because that's the signal to harvest! When about 80% of the trichomes have the amber color, you can start harvesting. The white hairs (pistils) on the buds also indicate harvest time by browning and retracting. Harvesting should begin when about 40-75% of the pistils have turned a brownish color.
More on the subject of harvesting, you will learn in our article "Harvest hemp - instructions & tips“.
The proper care of hemp in the flowering phase
What the optimal growing environment for your cannabis plant in the flowering phase should look like, you will learn below. We would like to remind you that if you are growing in a Bonsanto grow box, the Bonsanto "growing guide" is relevant for you. There you will learn everything you need to know for a successful grow in a Bonsanto grow box.
How much nutrients does hemp need in the flowering phase?
In the flowering phase, the nutrient and water requirements of your cannabis plant change compared to the previous growing or vegetative phase. During this time, your plant focuses on producing flowers, which requires a change in nutrient composition.
In general, the cannabis plant requires less nitrogen (N) during the flowering phase. Phosphorus (P) and potassium (K) are the substances your plant will benefit from the most during flowering. A commonly recommended NPK (nitrogen, phosphorus, potassium) ratio for the flowering phase is 1:3:2, although this can vary depending on the variety and specific nutrient program. We recommend that you primarily follow the fertilizer manufacturer's dosage instructions. Be careful not to overfeed your plant during flowering to avoid nutrient burn and stop fertilizing when your plant is nearing harvest.
How much water does hemp need in the flowering phase?
The water intake of a cannabis plant may increase during the flowering phase, as the plant grows and its leaves and flowers require more moisture. However, the exact amount of water a plant needs depends on many factors, such as the size of the plant, environmental conditions, and the type of grow medium the plant is growing in.
A good rule of thumb is to water the plants thoroughly and then wait until the top inch of soil is dry before watering again. Overwatering can lead to problems such as root rot and should be avoided at all costs.
What is the ideal humidity in the flowering phase?
Since too high humidity can lead to mold and fungus, you should pay attention to the right humidity in your grow room and of course during flowering. The optimal humidity for cannabis plants during the flowering phase is between 40-50%. Some growers even lower the humidity to around 30-40% in the last weeks before harvest to reduce the risk of mold and fungus.
Especially during the flowering phase, it is important to avoid too high humidity, because the plants become bushier than in the previous phases, and therefore mold and other diseases can spread more quickly.
How lighting in the flowering phase?
In the flowering phase, growers usually use an exposure of 12 hours of light and 12 hours of darkness per day. This 12/12 light cycle mimics the natural conditions of autumn when the days get shorter. This change signals to the cannabis plant that it is time to start flower production.
For the flowering phase as well as the entire indoor growing process, we recommend using an LED grow light. LEDs have the highest energy efficiency and longest lifespan compared to other lamps and emit less heat, which protects your cannabis from burns.
While cannabis prefers a light with a higher blue component in the growth phase, it needs a higher red component in the flowering phase. To avoid annoying lamp changes, it is advisable to use a full-spectrum plant lamp that you can use for all phases of your plant. If you are looking for a LED full-spectrum plant lamp, take a look at our Bonsanto grow lamps.
Flowering phase hemp - Tips
- Send your cannabis plant into flowering by changing the lighting cycle (12 h light/12 h dark)
- Use a full-spectrum LED lamp for the entire grow, which will provide your plant with reddish light when in bloom
- Ensure that the humidity in your grow box is around 40-50%.
- Fertilize your plant carefully during flowering and follow the fertilizer manufacturer's dosage instructions
- Do not give your plant any more nutrients in the last weeks before harvesting
- Use a Bonsanto Growbox to simplify your plant's grow and properly care for your plant in bloom