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When Does the Flowering Stage Begin?

For most cannabis strains, the first signs of flowering stage are 7 – 9 weeks into a plant’s lifecycle. During this period, there are a few important environmental changes to consider:

  • For outdoor plants, you’ll likely notice buds start to appear when days grow shorter. In other words, the flowering stage usually begins in the autumn months.
  • For indoor plants, in order to commence the flowering stage, it’s essential to keep the plants on 12 hours of light and 12 hours of darkness.
  • For autoflowering strains, a photoperiod is NOT necessary. In other words, these plants will automatically create buds (usually 4 weeks into its growth cycle).

How Long Does the Flowering Stage Last?

The flowering stage varies from one cannabis strain to another. For this reason, we highly recommend doing a bit more research concerning the strain you’re growing.

However, for most cannabis strains, the flowering stage is from weeks 8 to 11. Still, there are some variations of this time period to consider:

  • For Indica plants, the flowering stage can start anywhere from 8 to 10 weeks.
  • For Sativa plants, the flowering stage can start anywhere from 10 to 12 weeks.
  • For Hybrid plants, the flowering stage can start anywhere from 6 to 10 weeks.

Differences Between Male vs Female Cannabis Plants

In order to tell the gender differences between plants, the best indication is the pre-flower found in the green calyx.

In female plants, this pre-flower will appear as a pair of white hairs in a “V-form.” In male plants, it will look more like a little ball.

Furthermore, female plants start to bud 4 to 6 weeks after germination, whereas male plants flower 3 to 4 weeks after germination.

If you run into a plant that has characteristics of both female and male, then you have a true hermaphrodite on your hands. When it comes to mixed-gender plants, you can tell by the organs (anthers) that grow from the female plants. These are largely characteristic of bananas.

Environmental Factors of Flowering Stage

During the flowering stage, you’ll want to ensure the following are in-check:


As your cannabis plants begin to flower, it’s essential you place them in a photoperiod: 12 hours of light and 12 hours of darkness.

In fact, lighting during this stage is so essential, you’ll want to make sure you don’t allow ANY light to pass by during the dark periods. Even just a few seconds of light contamination can send your plants into revegetation.

Not sure what lights to use? Check out our guide for the Best LED Lights for Indoor Plants!

Temperature & Humidity

During the flowering stage, the best temperature for cannabis plants is 18° – 26°C (64.4° – 78.8°F).

Any temperatures under this range can have extremely negative effects on the plant. Namely, it may stunt growth and give the plant irreversible damage. When temperatures exceed this range, it can cause burned leaves, stunted growth, and too heavy evaporation of water.

On top of temperature, you’ll also want to keep humidity at 40% to 50% during this stage. This will help to prevent mold and fungi from growing on the plant.


While nutrients are essential for all stages of the cannabis plant, it’s essential to avoid nutrient deficiencies during the flowering stage. The most important nutrients for budding cannabis plants are Nitrogen (N), Phosphorus (P) and Potassium (K).

More specifically, a blooming cannabis plant will naturally create higher concentrations of Phosphorus and Potassium. Simultaneously, concentrations of Nitrogen will lower.

For these reasons, it’s important to ensure your plants are placed in soil that’s made for the vegetative (or flowering) stages.

In order for the best results, you’ll also need high concentrations of secondary nutrients:

  • Magnesium (Mg)
  • Calcium (Ca)
  • Sulfur (S).

On top of this, you’ll want lower concentrations of micronutrients:

  • Zinc (Zn)
  • Manganese (Mn)
  • Iron (Fe)
  • Boron (B)
  • Chlorine (Cl)
  • Cobalt (Co)
  • Copper (Cu)
  • Molybdenum (Mb)
  • Silicon (Si)


For the best results, you’ll want to use chlorine-free or filtered water. You’ll also want to keep a close eye on over-watering and ensuring your plants have good drainage.

If you’re not sure whether or not your plants are receiving enough water, you can stick your finger down into the soil a few centimeters (cms). If the soil is dry, then your plants are in need of water!

pH Levels

During the flowering stage, the best pH levels are between 6 and 7. These levels allow for nutrients to grow in a balanced manner.

If your pH levels exceed or weaken past these levels, your plants may experience deficiencies and toxicities. Namely due to the fact that soil is unable to absorb nutrients.

Environmental Factors of Flowering Stage

Pre-Flowering: First Signs of Flowering Stage (Week 1 - 3)

During this period, you’ll notice overall growth (in both width and height) in your plant. Many consider this the “transition phase” as plants will nearly double in size.

It’s also during this period when you’ll notice the female first signs of flowering stage: pistols appearing as “white hairs.”

This usually occurs later in the stage (about week 3) and will take place at the part where the main stem and branches meet. It’s important not to damage this part of the plant during this phase as it may prevent the full growth of the buds.

You should also pay attention to the way these buds look – if they appear as a vibrant green, they’re healthy. Any discoloration is a sign of deficiencies and should be tracked.

Mid-Flowering: Growth of Buds (Week 4 - 5)

During this stage, the plant itself will stop growing. However, the buds of the plant will fatten and darken.

Since this stage accounts for the main growth of your buds, it’s important to:

  • Make sure humidity is between 40% to 50%
  • Have temperatures slightly lower than normal
  • Keep light temperatures between 18° – 26°C (64.4° – 78.8°F)

It’s worth noting that this stage requires the most effort from your plant. Therefore, moving it (or tying it) may cause stress that can lead to problems with growth.

You may also notice older leaves start to yellow or fall off. This is normal: your plant is just processing nutrients from older leaves to newer ones. No need to be concerned unless you notice this discoloration happening among a lot of your cannabis leaves.

Late Flowering: Ripening Stage (Week 6 to Harvest)

During these last few weeks of the flowering stage, your buds will gain most of their weight (likely resembling the “nugs” you plan to harvest from your plant).

The most important thing to keep an eye out for during this stage is trichomes. These are sticky and rich glandules that appear on the outside of the cannabis bud. They’re filled with tetrahydrocannabinol (THC) and other cannabinoids.

When trichomes begin to change in color, that is when you know your cannabis buds are ready for harvest.