Marijuana light cycle: indoor—16 hours a day; outdoor—at least 6 hours of direct sunlight (“full sun”), plus several hours indirect sunlight
The biggest variability in how long a marijuana plant takes to grow will happen in the vegetative stage—after the seedling phase and before flowering.
The Spring Equinox is a good reminder that it’s time to kick off the outdoor growing process and start germinating your seeds.
Be mindful to increase your watering as the plant develops. When it’s young, your plant will need water close to the stalk, but as it grows the roots will also grow outward, so start watering further away from the stalk in the soil so roots can stretch out and absorb water more efficiently.
Marijuana light cycle: 16 hours a day
As roots develop, the stalk will rise and you’ll begin to see the first iconic fan leaves grow, at which point your cannabis plant can be considered a seedling.
Two rounded cotyledon leaves will grow out from the stem as the plant unfolds from the protective casing of the seed. These initial leaves are responsible for taking in sunlight needed for the plant to become healthy and stable.
The way these differ from photoperiod plants is written in the name. Regardless of whether you feel the plant is ready, it’ll start flowering at a certain time depending on the strain’s genetic programming. In one sense, these plants are easier for novice growers because there’s less to think about in regards to light coverage and cycle adjustment. On the other hand, due to the limited vegetation time, you have fewer opportunities for mistakes. This isn’t ideal for first-timers, but the fact that it only takes two months from germination to harvest is definitely appealing. Autos tend to produce lower, milder yields than their photoperiod counterparts, but modern advances are bridging the gap.
Aside from the buds themselves, another way you can tell your plant is approaching harvest is by examining the colour of the leaves. Provided you haven’t overfed your plants during the final stage of flowering, a yellowing of the leaves will signal that your plant is reaching peak maturity, and that its nutrients are being fully utilised by the buds. By flushing out nutrient salt buildup with pH-balanced water for a couple weeks before harvest, a smoother, more pleasant smoke is guaranteed from each plant.
At this stage, the focus of the grower and plants switches to the production of buds and the grower is already dreaming of a frosty marijuana harvest in the near future. RH needs to be reduced to 40-50% and temps kept between 20-28°C.
Breaking through the germination stage, plants enter the seedling stage next. At this point, they’ll need about 18 or more hours of daily light. After two or so weeks of proper care, though, they’ll be well on their way to robust growth.
Another sign that your buds are maturing is when the pistils of the flowers change colour. Pistils are small-hair like structures that grow out of the calyxes, and are the reproductive organs of the female cannabis plant. They are the site where pollination occurs—if male pollen were allowed to land there. Pistils appear bright white during the early stage of the grow cycle, and eventually shift to an orange-brown colour.