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Effectively facilitating the flowering process in cannabis plants constitutes one of the most intricate facets of cannabis cultivation. During this critical juncture, it is imperative that the plants receive detailed attention and meticulous care to realize significant yields. It is now, more than ever, vital to maintaining an optimum balance, as errors at this stage can be significantly challenging to amend.
What initiates the flowering phase in cannabis plants?
Cannabis generally behaves as a short-day botanical species, initiating its flowering phase when there is a discernible decrease in daylight hours. In a natural, external setting, this transition is manifested as the seasons evolve from summer to autumn. It is commonplace for these plants to commence their flowering phase approximately a month before the arrival of the autumnal equinox, reaching maturity ready for harvest by the conclusion of October in the northern hemisphere. However, it is to be noted that certain strains with an extended flowering duration might necessitate a time frame extending to late November or potentially early December, provided the climate conditions are sufficiently mild to foster their growth.
The aforementioned assertion is applicable predominantly to the majority of commercially available cannabis strains, which often encapsulate a substantial quotient of “Indica” genetic lineage. Essentially, they are derivatives of plant species native to the temperate highland regions of India and Afghanistan, locales characterized by pronounced hot and luminous summers followed by cool, dark winters. Consequently, these plants have evolved to reach full maturation and initiate the flowering process before the onset of the wintry chill. This progression is fundamentally driven by the stark fluctuations in the duration of daylight, serving as a potent catalyst to instigate the flowering phase.
Sativa and Ruderalis Varieties
In cannabis variants predominantly classified as “Sativa” or “Ruderalis”, the flowering process adheres to slightly diverse protocols. Ruderalis varieties, which are adapted to colder climates, initiate flowering autonomously, propelled by a series of genetic triggers that are activated based on the plant’s level of maturity rather than the photoperiod (the duration of daylight it receives). Similarly, tropical sativas might embark on the flowering phase autonomously, even though the underlying genetic intricacies governing this process remain intricate and partially enigmatic.
Regarding ruderalis, these plants are constrained to a brief timeframe to fulfill their life cycle since the prevailing temperatures and luminous intensity are predominantly inadequate to sustain life throughout extensive durations of the year. Consequently, these plants have evolved to grow and blossom expeditiously within a single season, specifically from late spring to summer. Dependence on seasonal shifts to incite flowering is an unfeasible evolutionary tactic in these regions. The flora that has the capability to flower spontaneously and generate seeds before succumbing to the harsh climes of the cold northern autumn exhibit greater evolutionary fitness, thus solidifying their presence in such habitats over thousands of years.
In contrast, tropical sativas experience minimal climatic fluctuations, presenting them with an almost perpetual growing season. Despite the subdued changes in daylight hours that do transpire, they facilitate the maintenance of a generally annual life cycle for cannabis in these environments. Consequently, in their native surroundings, sativas are granted extensive periods to vegetate at a leisurely pace prior to entering the flowering stage. When the flowering stage is initiated, it is a process influenced partly by environmental signals and partly by the plant’s own developmental maturity.
Indoor Blossoming of Cannabis Plants
In the context of indoor cultivation, the transition to the flowering stage can be meticulously managed by modifying the light schedule. It is customary for cultivators fostering cannabis indoors to illuminate their plants for an extended duration, spanning 18 to 24 hours daily, throughout the vegetative growth phase. To initiate the flowering phase, the daily light exposure is reduced to 12 hours. In an effort to replicate the natural outdoor cycle more faithfully, some cultivators choose to gradually lengthen the durations of darkness over a period of 2 to 3 weeks.
Certain cultivators opt to initiate the flowering phase by subjecting the plants to an uninterrupted dark period extending from 24 to 48 hours before adopting the 12/12 light-dark cycle. This practice is believed to facilitate a swift transition to the flowering stage, as it is hypothesized that the majority of florigen synthesis, colloquially known as the “flower hormone”, predominantly occurs during nighttime. Although this method seems to be more rooted in anecdotal evidence rather than a scientific foundation, it remains a widely acknowledged practice among growers. Furthermore, scientific investigations into extended dark periods, spanning up to 16 hours for short-day plants, have been undertaken, revealing no detrimental impacts on the plants.
Indoor Flowering of Sativa and Ruderalis Cannabis Plants
When cultivating predominantly ruderalis-based strains indoors, it’s common to maintain a consistent 18-24 hours of daylight throughout the entire growth cycle. These plants will typically initiate flowering when they reach a height of around 50cm, although some “super-autos” may grow as tall as 90-100cm.
For sativa-dominant varieties grown indoors, growers often adhere to the 18/6 and 12/12 lighting systems. However, there is an alternative approach where plants are exposed to just 10 hours of light and up to 14 hours of darkness daily. While anecdotal reports suggest that this extended darkness period can accelerate flowering and reduce the overall flowering time, it’s advisable to start with a 12/12 cycle and gradually shift to a 10/14 cycle over approximately one month if choosing this method.
Another viable approach is to maintain a 12/12 (or a similar) light cycle throughout the entirety of the plant’s life cycle. In general, sativas tend to enter the flowering phase after 3-4 months of vegetative growth under this regimen. However, providing approximately 18 hours of light during the vegetative stage can potentially enhance the plant’s growth rate and expedite its maturation. As a result, the plants may become ready for flowering earlier when the lighting is transitioned to 12 hours or more of darkness.
Environmental Conditions in the Flowering Stage: Temperature and Humidity
During the vegetative growth stage of cannabis plants, they exhibit a higher tolerance for elevated temperatures compared to the flowering stage. It is generally recommended to maintain daytime temperatures in the range of 24-32°C (75.2-89.6°F) for optimal vegetative growth. However, once the plants transition to the flowering stage, it is advisable to avoid exposing them to temperatures exceeding 28°C (82.4°F). It’s worth noting that certain strains with tropical origins may have a higher tolerance for warmer temperatures.
The temperature differential between day and night also plays a significant role during flowering. A larger temperature contrast is believed to aid in the induction of flowering, as it simulates the natural conditions of warm days followed by significantly cooler nights that typically signal the arrival of autumn. The ideal temperature difference is considered to be 8-10°C (14.4-18°F). For instance, if daytime temperatures are maintained at 28°C (82.4°F), nighttime temperatures should ideally fall within the range of 18-20°C (64.4-68°F).
Humidity levels should be moderated during the flowering phase, particularly as it progresses. As the flowers become denser, they become more susceptible to mold growth. During the vegetative growth period, it is advisable to maintain humidity levels at approximately 60-70%. However, as the plants enter the flowering stage, it is prudent to reduce humidity to a range of 40-50%. It’s important to note that certain tropical strains with lightweight, airy flower structures can often tolerate higher humidity levels during flowering, sometimes up to 70%.
When it comes to watering practices during the flowering stage, a strategy of frequent but small waterings is generally recommended. Providing the plant with more water than its root system can immediately absorb can result in a consistently damp growing medium, which in turn accelerates the rate of evaporation. Therefore, controlling the amount of water given helps regulate humidity levels and prevents potential issues such as pythium (root rot) and botrytis (grey mold). However, it’s essential to consider the specific growing medium, as some media have better moisture retention properties than others and may require less frequent but larger waterings.
