Feminized seeds are genetically designed to produce female cannabis plants, which develop the cannabinoid-rich flowers growers seek. This eliminates the need to identify and remove male plants, maximizing usable yield. The flowering period is a key consideration for growers planning cultivation cycles. While some feminized seeds are autoflowering, this article focuses on photoperiod varieties, whose flowering time is controlled by the grower.
The Critical Transition to Flowering
The onset of the flowering stage in photoperiod cannabis is a direct response to an environmental signal. Plants rely on a change in the light cycle to transition from the vegetative stage to the reproductive stage, rooted in sensitivity to uninterrupted darkness.
For indoor cultivation, this change is achieved by switching the light schedule from 18 or more hours of light to 12 hours of light and 12 hours of darkness. This extended darkness mimics the shortening days of late summer. The plant interprets this signal as the time to complete its life cycle by producing flowers, allowing the grower to dictate when flowering begins.
Standard Flowering Timelines by Genetic Type
The total duration of the flowering stage is influenced by the genetic background of the strain. This timeline refers to the period from the light cycle flip until the plant is ready for harvest. Durations are averages and can be extended or shortened based on environmental conditions.
Strains dominant in Cannabis indica genetics are the fastest, typically requiring 8 to 10 weeks (56 to 70 days) after the 12/12 light cycle initiation. This shorter cycle is popular for indoor growers aiming for more harvests per year.
Conversely, Cannabis sativa dominant strains have longer flowering periods, often requiring 10 to 14 weeks or more. This extended maturation is inherited from their equatorial origins.
Most modern feminized seeds are hybrids, representing a cross between Indica and Sativa genetics. Depending on the hybrid’s lean, the flowering duration commonly ranges from 9 to 11 weeks, though minor environmental stress can slightly prolong maturation.
Key Phases of the Flowering Stage
The overall flowering duration is a sequence of distinct developmental phases. Understanding this progression helps growers anticipate the plant’s needs.
Transition/Stretch Phase (Weeks 1-3)
The initial weeks, often called the stretch phase, cover approximately weeks one through three. The plant experiences rapid vertical growth, sometimes doubling its height. Pre-flowers (small wisps of white hairs known as pistils) appear at the nodes, confirming the plant’s female sex and transition into bloom.
Mid-Flower Phase (Weeks 4-6)
Weeks four through six mark the core of the flowering stage. The plant shifts energy from vertical growth to flower development and bulking. The initial clusters of pistils swell, and the foundational structure of the buds starts to densify. The plant’s aroma intensifies due to the increasing production of terpenes and cannabinoids.
Ripening Phase (Week 7 to Harvest)
The final phase, from week seven until harvest, focuses on ripening. Vertical growth has stopped, and the plant concentrates on increasing the density, weight, and resin content of the flowers. Trichomes begin their final synthesis of cannabinoids, leading to peak potency.
Identifying the Optimal Harvest Window
The genetic timeline offers a solid estimate, but the indicator of maturity is determined by visual cues on the flower itself. Relying solely on projected weeks risks compromising the quality of the final product. The most precise method involves monitoring the appearance of the resin glands, or trichomes.
Growers use a magnifying tool, such as a jeweler’s loupe, to inspect the color of the trichome heads. Initially, the heads are clear, indicating that cannabinoids are immature. As the plant approaches its peak, trichomes turn cloudy or milky white, signaling the highest concentration of THC and a more euphoric effect.
A later harvest is indicated when a portion of the trichomes turns amber, suggesting that THC has degraded into cannabinol (CBN) and leading to a more sedative effect. The optimal harvest window is when most trichomes are cloudy, with 10 to 30 percent having turned amber. A secondary visual cue is the color and recession of the pistils, which change from white to orange or brown and curl inward.