My inspiration for writing this article, creating seasons growing indoors, was an email I received. A grower asked me why I used a lighting photoperiod of 16/8 (16 hrs. ON/8 hrs. OFF), when I normally vegetate using 18/6 and flower using 12/12 photoperiods. During my reply, he had an epiphany. He really “got” my methodology here and how it mimics Mother Nature. His skills just came up—wink.
Today, I want to do the same thing for any of you that don’t get this part of growing cannabis indoors. You have to understand a little bit about how your plants perceive things and why. So, I decided to lay it all out here, and hopefully, it will all come together for you by the end of the article. Let’s roll…
Why Create Seasons Growing Cannabis Indoors?
Okay, peeps, here’s the part where we think like plants the best we can. If you were a plant, you would move in uber-slow-motion, so slow that it is another dimension in which humans cannot see the movement of plants. Only over time can we see that they have grown (moved). Plants are much slower to react to things. Creating seasons is simply keeping them super happy and unconfused—proactively.
Cannabis plants only live (naturally per their genes) for less than a year; that’s their whole lifespan. At that time, their main objectives are two-fold and in two completely different growth modes, wholly.
- Grow leaves, stems, and roots rapidly to outcompete other plants and to assimilate and store nutrients to use for flowering while they are in vegetative stages of growth.
- Create flowers (calyxes, pistils, trichomes) for procreation, and resin, root growth continues, and different ratios of nutrients are sought after. Some leaf and stem growth continue. Stored nutrients are retrieved. All while they are in flowering stages.
Cannabis plants are either in vegetative growth mode or flowering growth mode. They don’t do both at the same time well. They judge when it’s time to shift modes by their current day/night hours and if the daylight hours are increasing or decreasing. Indoors we can manipulate that just fine using photoperiods. Plants follow a linear path from youngster to adult, mature adult, and flowering adult.
Why All This Matters
Plants take about 2-weeks to react visibly to photoperiod changes. Remember the stuff I said about how slow motion they are? Okay, so plants really like to prepare for things and know where they stand. For example, they will gauge their container resources once flowering begins to allow them to have enough food to last to the end. Their growth rates will conform. In vegetative mode, they are more “risk-takers,” pushing the limits of their container resources. This is why I always transplant just before starting flowering. The plants have a whole new container to assess. They love that.
So, for my plants to be chugging along at full power with full happiness, they need to know “what time of the year it is” according to their photoperiod trend. When plants have 16 hours a day of light, they have more energy to do things than growing under a 12/12 photoperiod. You savvy? Allowing your plants to prepare for seasonal changes allows them to transition much better into flowering. Mother Nature doesn’t go from 16 hours of daylight per day to 12 hours overnight. Plants have a lot of time to transition with lots of sunshine power to do it with. Or, in our case here, growing cannabis indoors, lots of light power. It’s fine; we got that covered.
Photoperiods Growing Cannabis Indoors
What I do is transition my plants slowly through their own seasons by changing my photoperiods more subtly. Now, if you look at your regular outdoor daylight hours around springtime, you will see they are actually well below 16/8 and closer to 12/12 actually. Let’s have a look at my lighting schedule next. Then I’ll break it down for ya…
- Sprouts always get a 12/12 photoperiod for their first ten days above ground.
- After those ten days, I use an 18/6 photoperiod.
- About ten days before flowering, I use a 16/8 photoperiod.
- During flowering, I use a 12/12 photoperiod unless I am flowering heirloom/landrace sativas.
Here’s the bennies. Using the 12/12 photoperiod when the plants sprout, they aren’t sure what season it is yet. Once it hits 18/6 the light is increasing (trending upwards) so this makes the plants assume it is indeed springtime and all is well with their world. Not to mention this makes it easier to sex them at 30 days of age.
Photoperiods from Vegetative to Flowering
10-days before flowering time, I change their photoperiod to 16/8, and this is before I transplant them. That loss of “daylight” hours for them signals them that fall has come, and it’s time to start switching things up to go into flowering mode. Giving them that 16 hours of light while still signaling them to begin flowering preparations gives them lots more energy (per day) to make that transition. After those ten days, I transplant them, and within a couple of days, I switch them to a 12/12 photoperiod.
Creating seasons growing indoors is massively beneficial to reducing stress, better yields, higher quality, and greater resin production, along with overall plant health/heartiness. What’s not to love? ❤ Signaling your plant’s flowering time is approaching, along with signaling them as youngsters that it is indeed springtime, will give your plants a level of happiness you will for sure notice huge.
Never, ever use a photoperiod of 24 hours ON at any stage of growth. If you did a 24/0 photoperiod to sprout them, then put them under an 18/6 photoperiod, they would “think” that fall was approaching due to the loss of daylight hours, you dig? They would start their lives very confused and stressed that they may have sprouted too late in the year/season. That’s a HUGE problem if you only live for one season.
Photoperiods for Cuttings
I use a standard vegging photoperiod of 18/6 to root cuttings. The only time you would want to use a different photoperiod would be if you were matching up clones for placement outdoors. Because any decrease in your daylight hours will signal the plant that “fall is approaching!” The plants begin switching into a whole new mode to prepare to flower. They use nutrients differently, and they change over to floral priorities. So, if you take a plant out from a cloner or a seedling plant and have it vegging at an 18/6 photoperiod, and you then place that clone/plant outdoors, even though it’s actually springtime, the diminished daylight hours will signal the shift in the plant’s priorities. This is why you sometimes see plants try to flower when you first place them outdoors from indoors.
To do that indoor seedling plant to outdoor plant thing better, you have two choices…
- Plant later, and place the plant(s) out later in the season, like mid to late June. This is fine, don’t sweat it. Use the 12/12 for the first ten days, then to 15/9 or whatever matches your current daylight hours. Your actual daylight hours outdoors are in fact, about 1 hour more than sunrise to sunset.
- Sprout at 12/12 and after ten days, take them up to 14/10 or something, whatever is about equal to your current daylight hours, then place outdoors earlier in the season. This signals them it is indeed spring, and their transition outdoors will be seamless as the daylight hours continue to increase.
Total darkness during the 10-day pre-flowering 16/8 photoperiod is required here. My vegging area is very dark during lights-out but not totally pitch black like the flowering area. Spectrum changes are also a thing when it comes to flowering, and you want your plants to be prepared if you are changing light spectrums to flower under. The simple solution is just to put them under their flowering lights dropped from an 18/6 to a 16/8 photoperiod for ten days before switching to your flowering photoperiod.
Growing cannabis indoors, clones always work much better, in my experience. Seedling plants always do MUCH better outdoors in the ground than clones do. If you are using clones to place outdoors, try placing them outdoors later in the season, and you’ll have less of that shift to try to flower for a minute.
Okay then, I’m outty for now, and I’ll see ya back here next Tuesday, baybee. Grab a copy of my TLO book, and make sure to swing by KOS for some deadly seeds to start your uber-happy gardens with. If you want to read some more stuffs from yours truly, check this out: Letters to Rev – Transplanting Cannabis in Living Soil. L8r G8rs…
– REv ?
Photo Credits: The Rev
I'm The Rev, and I have been with SKUNK for about a decade now. I hail from Southern California, spent mucho time in Northern California, and now reside in Southern Oregon; always coastal. I am an all natural style cannabis grower and I have written a couple books on the subject - check out True Living Organics 2nd Edition on Amazon - I have been growing for over 45 years, and I have been breeding cannabis for over 30 years. Check out kingdomorganicseeds.com to see some exotic selections. Growing connoisseur cannabis is what I teach mostly, growing it in living soil without using liquid organic nutrients to feed the plant. I am also a highly skilled synthetics grower, hydroponics, aeroponics, DWC/SWC/NFT, Ebb and Flow, and soilless, but I cringe when smoking synthetic grown herbs, so for the last 15 years or so I preach the artisan style of all natural growing, specializing in container growing. Cheers and welcome aboard.