Transitioning to the Blooming Stage
The timing of when your plants begin to flower depends on several factors. If you’re growing outdoors, this phase will naturally start toward the end of summer when daylight hours become shorter. However, if you’re growing indoors, you’ll have much greater control over initiating and managing the flowering stage. Typically, indoor growers transition their plants to bloom after about four weeks of vegetative growth, though technically, plants can remain in this phase as long as you choose.
When your plants receive less light, they instinctively shift their energy from growing foliage to producing buds. To achieve the best possible results, it’s crucial to support this process with the right combination of nutrients, lighting, and environmental conditions.
Below, you’ll find a comprehensive guide to a standard eight-week flowering cycle. While some strains may have shorter or longer bloom periods, this guide will give you insight into what to expect as harvest time approaches and offer tips to enhance the quality and yield of your buds during this critical stage.
Weeks 1–3
• What to expect: Intense flowering stretch, the appearance of white pistils, and the onset of noticeable aromas.
A common misconception among growers is that cannabis plants stop growing as soon as the flowering phase begins. In reality, the first few weeks of flowering are marked by rapid vertical growth, often referred to as the "flowering stretch." This stage allows plants to outgrow competing vegetation, improving light exposure and reproductive success. During this time, plants exhibit longer internodal spacing, which provides room for flower development and better light penetration. Depending on the strain, plants may even double their height during this phase.
By week two, you can usually identify the sex of your plants. Female plants develop long, white pistils at their nodes—future bud sites—while male plants grow round pollen sacs. If you're using regular seeds and not aiming to breed, remove male plants early to prevent pollination.
As week three approaches, plants will gradually shift their energy from stretching to bud production. Bud sites become more defined, calyxes begin to swell, and the first signs of trichomes appear, offering an exciting preview of the frosty flowers ahead.
Providing proper care during this crucial phase is key to achieving optimal results. For detailed tips on maximizing growth and flower formation, check out our 'Cannabis Flowering' video guide.
Best Practices
• Nutrients: Adjust your feeding regimen to align with the plants' new needs. Introduce a nutrient mix higher in phosphorus and potassium, while gradually reducing nitrogen. Avoid overfeeding to prevent nutrient burn. By week two, you may need to increase feeding as plants adapt to the flowering phase.
• Deficiency and Overfeeding: Transitioning between vegetative and flowering nutrients can be tricky. Monitor your plants closely for signs of deficiencies (e.g., yellowing leaves) or overfeeding (e.g., burnt foliage) and make adjustments as needed.
• Low-Stress Training (LST): Manage the height gained during the stretch by applying LST techniques. This helps create an even canopy and ensures better light penetration for lower buds.
• Temperature: Cooler temperatures can enhance flower development. Aim for daytime temperatures around 26°C and nighttime temperatures between 16–18°C. Lower nighttime temperatures can improve both flower density and quality.
Weeks 3–4
• What to expect: Rapid bud growth and increasingly intense aromas.
By weeks three and four, the flowering stretch is complete, and plants focus entirely on producing buds. You’ll notice flowers becoming larger and denser, with thickening calyxes, prominent white pistils, and a visible layer of trichomes. Aromas will grow more complex and pronounced, signaling the transition into mid-flowering.
Best Practices
• Feeding: As flowers develop, plants will require increased nutrients. Focus on phosphorus and potassium for optimal bud growth. A mid-flowering NPK ratio, such as 6-10-15, is a great starting point. Watch for signs of nutrient imbalances and adjust as necessary.
• Humidity and Airflow: Prevent mold and pests by maintaining humidity levels between 40–50%. Good airflow is vital—use fans or a ventilation system to ensure consistent circulation.
Weeks 4–6
• What to expect: Dense buds, peak flowering, and stronger aromas.
During weeks five and six, plants will reach the peak of their flowering period. Buds will grow dense, thick, and heavily frosted with trichomes, while their aroma intensifies further. If not already done, consider installing an air filter or extractor fan to manage the scent.
At this stage, buds become heavier and more compact. Early-maturing strains may begin to show signs of nearing harvest, such as darker pistils and increased trichome production.
Best Practices
• Feeding: Nutritional needs peak during this phase. Keep nitrogen low and prioritize phosphorus, potassium, and calcium to boost bud growth. Remain vigilant for symptoms of nutrient burn or deficiencies.
• Plant Support: Heavy buds can weigh down branches, increasing the risk of breakage. Use bamboo stakes, plant ties, or other supports to keep branches sturdy.
• Humidity and Temperature: Lower humidity to 30–40% to minimize mold risks. Maintain stable temperatures to prevent undue stress on your plants.
Weeks 6–8
• What to expect: Full bloom and harvest readiness.
The final weeks of flowering reveal your plants’ full potential. Buds will be firm, dense, and covered with a thick layer of trichomes. As they mature, trichomes will transition from clear to milky white, with some turning amber—these are key indicators of ripeness. Pistils will darken further, signaling that harvest time is near.
Two weeks before harvest, begin flushing your plants with pH-balanced water to remove excess nutrients, which enhances flavor. During this time, yellowing leaves are normal as plants deplete their nutrient reserves in preparation for harvest.
Remember, harvest timing affects your buds' effects. Harvesting slightly early results in an uplifting high, while waiting longer produces a more sedative effect due to compounds like CBN and myrcene.
Best Practices
• Nutrient Flush: Use pH-balanced water during the final two weeks to remove nutrient buildup and enhance flavor.
• Humidity: Keep humidity levels between 30–40% to prevent mold in dense buds.
• Trichome Monitoring: Use a magnifying glass or pocket microscope to assess trichome maturity and determine the perfect harvest window.
Patience Pays Off: Don't Harvest Too Soon
As harvest approaches, it’s natural to feel excited, but it’s crucial to avoid harvesting prematurely. Even waiting an extra week can significantly improve your buds’ flavor, potency, and overall quality. Stay attentive, exercise patience, and your efforts will be rewarded with premium, top-shelf results.