Autoflowering cannabis plants are a unique variety that begins to flower based on its age rather than a change in the light cycle. This genetic trait allows for a dramatically compressed cultivation schedule compared to traditional strains. The time from planting the seed to harvest generally ranges from eight to twelve weeks. This rapid, fixed timeline is the primary characteristic that distinguishes autoflowers.
The Standard Autoflower Timeframe
The typical duration for an autoflowering plant to complete its entire life cycle is between 60 and 90 days from the moment the seed germinates. This means a grower can anticipate a finished product in approximately two to three months under optimal conditions. This rapid growth speed is directly inherited from Cannabis ruderalis genetics, a subspecies native to regions with short growing seasons.
Unlike photoperiod cannabis, which requires a reduction in light hours (often a 12/12 cycle) to trigger flowering, autoflowers do not depend on this environmental cue. The ruderalis trait ensures the plant automatically switches from vegetative growth to flowering after reaching maturity. This built-in biological clock simplifies the process and accelerates the overall timeline.
Breakdown of Growth Stages
The overall growth period is divided into three distinct phases.
The Seedling Phase is the shortest, typically lasting for the first one to three weeks after germination. During this fragile stage, the plant focuses on establishing a strong taproot and developing its initial set of true leaves. It is a period of foundational development where the plant is highly susceptible to stress.
The Vegetative Phase follows and is remarkably brief, generally spanning only two to four weeks. Autoflowers have a short, predetermined vegetative period, during which they rapidly grow their structure, stems, and fan leaves to support later flower production. The switch to flowering is automatic, often occurring around the third to fifth week of life.
The Flowering Phase is the longest stage, lasting approximately four to eight weeks. During this time, the plant focuses all its energy on bud development, culminating in the maturation of the flowers. A typical autoflower will complete its entire cycle in about 75 days, with the final weeks dedicated to the buds becoming dense and resinous.
Variables that Affect Duration
While the 8-to-12-week window is the standard, the exact finish time is susceptible to several internal and external factors.
The most significant variable is the specific genetics. Some varieties are selectively bred for extreme speed, finishing in as little as eight weeks, while others, known as “super-autos,” may take 12 to 15 weeks due to their Sativa heritage. Sativa-dominant autoflowers tend to have a slightly more extended flowering period than Indica-dominant ones.
Light schedule and intensity also play a large role in maximizing growth within the fixed timeframe. Although light cycles do not trigger flowering, insufficient light intensity or duration will cause the plant to grow slower and may not reach its full potential size or yield. Growers often use an 18-hours-on, 6-hours-off (18/6) light schedule to provide maximum energy.
Finally, severe environmental stress can delay the entire life cycle. Issues such as transplant shock or nutrient deficiencies can temporarily halt the plant’s development. Since the autoflower’s vegetative stage is fixed and short, any stunting during this early period cannot be corrected by extending the growth time, causing the plant to finish smaller.
Signaling the Final Finish
Since the calendar date provides only an estimate, growers must rely on physical cues to determine the exact moment of harvest. The initial visual indicator is the color of the pistils, the small, hair-like structures emerging from the buds. These start out white and, as the plant matures, they darken and curl inward, turning shades of orange, red, or brown. A common guideline is to aim for harvest when 70 to 90 percent of the pistils have changed color.
The definitive method for confirming maturity involves examining the trichomes—the tiny, mushroom-shaped glands covering the flowers—using a magnifying tool. Trichomes progress through three phases: clear, cloudy/milky, and amber. Harvesting when the trichomes are mostly cloudy indicates peak cannabinoid potency, resulting in a more energetic effect. Waiting until a portion of the trichomes turns amber (typically 20 to 30 percent) suggests the degradation of THC into compounds that produce a more relaxing or sedative effect.