Seed to Harvest: Part 4- Growing Conditions: Light Cycles Indoors and Out

In this series, we’ve looked at marijuana genetics: varietal selection, types of seeds, and clones. Once you’ve got the genetics, you are on to growing.

Marijuana grown indoors requires significant controls to create an ideal growing environment. Many people know that flowering, or bud production, is triggered and maintained by the introduction of a 12 hours on, 12 hours off light cycle. Temperature, humidity and air circulation are other crucial environmental factors determining the production of marijuana.

All of the work that goes into engineering a marijuana grow facility is aimed at learning from and improving the natural conditions in which the plant thrives. There are ideal ranges for temperature and humidity, and sufficient airflow is necessary to prevent stagnation. The irony is that while the ideal conditions for marijuana plants to thrive indoors are precise, the plant thrives in an incredible variety of climates outdoors. It is for this reason that the common belief that indoor grows are designed mimic nature is not quite accurate.

Outdoor plants are grown in the summer, when bud production is triggered by the change in photoperiod. That’s when it is 12-12, which throws the plants into flower, right? Yes, but that is definitely an oversimplifcation. At and near the equator, there is a constant photoperiod of 12-12, so plants can flower outside at any time of the year in, say, southern Columbia.

More interestingly, outdoor plants actually need at least twelve hours of light per day, not exactly. This can vary from strain to strain, and some indoor growers have experimented with flowering in, say, a 14-10 cycle (fourteen hours of light and ten hours of darkness) for a specific strain in order to increase yield.  This is likely due to the fact that marijuana evolved and adapted to grow all around the world, from Papua New Guinea to Morocco to Paraguay. The natural light cycle around the world varies wildly. Places further from the equator have more drastic light cycle changes. In the marijuana world, Alaska is famously anomalous: the light cycle doesn’t approach 12-12 until late September.

The variety of climates in which cannabis can thrive is truly amazing, as is the work that cultivation facilities must do, not to mimic nature, but create an ideal growing environment.