Cannabis is a short day plant. That’s because the dark cycle dictates the pace of growth for photoperiod marijuana. There are thousands of blogs about lighting and a dearth concerning the dark cycle; so we’ve gone Darth Vader and invite you to join us on the dark side of sinsemilla.
Grow tents and grow rooms need to be checked for cracks and tears. Greenhouses can be covered to make sure nighttime is completely dark as long as it needs to be. It doesn’t take much to patch a hole or buy a light-proof tarp. But interruptions to the dark cycle during flowering could cost you a whole harvest.
PHOTOSYNTHESIS & RESPIRATION
The 24-0 schedule might speed up the vegetative growth process some. The downside is the higher power bills. 18-6 is more common because it’s a closer match for long summer days and a little cheaper. Higher success rates with cuttings on an 18-6 light-dark cycle than those receiving 24-0 is the only substantial difference we have discovered from our own experiments.
When cannabis plants, like other green plants, are in the light—be it sunlight or artificial light—they are photosynthesising. This is how they convert light into energy and release oxygen. They are also respiring. That’s right, contrary to the misinformation circulating elsewhere, plants, like all other aerobic organisms, are respiring all the time. We stop when we die, and we die if we stop. Cannabis plants are just producing a surplus of oxygen during the daytime.
12-12, the even split of 12 hours of light and 12 hours of darkness, only occurs naturally close to the equator. Indoor growers rely on timers to artificially dial in this light-dark cycle. During the day or lights-on period, two receptors, phytochrome red and phytochrome far-red, are in balance. In darkness, the far-red change into red. It’s the increase in red that triggers flowering. Many growers leave plants in complete darkness for 36 hours before commencing 12-12 to ensure a high phytochrome red ratio.
Using the right light spectrum is super important when growing any type of cannabis plant, including autos. Because autoflowering plants have such short life cycles, you really want to maximise the quality of light, nutrients, and soil you give them.
Some growers will even give their autos a full 24 hours of light, arguing that this helps maximise vegetative growth. Growers who stick to 18-hour light cycles, on the other hand, argue that this gives their plants a short “recovery” period that is essential for healthy growth.
Growing autoflowering strains? In this article, we explore the ideal light schedule to help your autos produce the best possible harvests.
A NOTE ON LIGHT SPECTRUM
Some growers still decide to keep their autos under a 12/12 light cycle during flowering. And that’s fine, as autos grown in these conditions can still produce a fair harvest. Just remember that the buds you harvest under a 12hr light cycle will be noticeably smaller than what you’d get under a 18–24hr cycle. Some reasons you might consider keeping your autos under 12/12 include:
SOG, or sea of green, is a cannabis training technique that can produce some great harvests. Rather than getting your plants to grow as large as possible, SOG involves growing several smaller plants in close proximity to form a uniform canopy that maximises light exposure and space.
Depending on the size of the particular strain you’re growing, we recommend using 7–10l pots and growing between 4–6 plants per m². This should make the most of your space and lighting while still providing your plants with enough airflow to avoid any mould issues. If you decide to grow more plants per m², remember to use smaller pots to control their size and avoid overcrowding your grow room.
SOG is a great technique to try with autos because it takes advantage of the naturally smaller stature of these varieties. While every grower will have their own technique for SOG, most will grow between 4–16 plants per m², depending on how big they let each plant grow.
Some outdoor growers start their plants indoors to give them a headstart before putting plants outside.
Cannabis is a "photoperiod" plant, which means the amount of light received each day decides when the plant starts flowering or making buds. This article explains how much light a day your photoperiod cannabis plants need to grow and start budding, so you get to a happy harvest day. What about auto-flowering strains?
So indoor growers have a choice to flower their plants whenever they want… When is the best t ime to start flowering your cannabis indoors?
For growers starting with cannabis clones, generally you should wait a few weeks longer than with seeds. Cannabis clones are more prone to flowering early outdoors than seeds, so you might want to put your clones out in late Spring or early Summer. (What are clones?)
It's important to make sure plants aren't exposed to light at night during their dark period, even street lights or spotlights, as this can prevent cannabis plants from flowering properly.
Once the plant is changed over to the flowering (12/12) light schedule, there is generally another 6 weeks-5 months (average 2.5 months) before the plant's buds are ready for harvest.