The Perfect Light Schedules For Autoflowering Cannabis
Growing autoflowering strains? In this article, we explore the ideal light schedule to help your autos produce the best possible harvests.
WHAT’S THE BEST LIGHT SCHEDULE FOR AUTOFLOWERING CANNABIS?
Autoflowering cannabis strains flower based on age, rather than a change to their light cycle. Nonetheless, providing your autos with the right amount of light remains crucial to ensuring the best possible harvest. Read on to learn all there is to know about lighting for autoflowering cannabis strains.
18/6 LIGHT CYCLE
Cannabis is a C3 plant, meaning it can absorb CO₂ for photosynthesis even during light hours. And since autoflowering plants have short vegetative phases and often grow shorter than photoperiod strains, you’ll typically want to give your autos at least 18 hours of light. This allows for robust growth, without overspending on energy. Your autos love light just as much as traditional photoperiod strains, they just don’t rely on it to begin bloom.
24HR LIGHT CYCLE
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.
There’s no real consensus on whether autos grow better under 18 or 24 hours of light, and we’ve seen growers achieve great results with both methods. To make up your mind, we recommend playing around with both variations and sticking to what works best for you.
WHAT ABOUT A 12/12 LIGHT CYCLE?
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:
- Heat concerns: If you live in a very hot climate, you might want to turn your grow lights off during the day to avoid overheating your grow room. In that case, growing your autos under a 12/12 light cycle—with lights on during the night—might be your best bet to avoid causing your plants heat stress.
- Growing autos alongside photoperiod strains: If you’re growing autos alongside feminized photoperiod strains, you’ll likely have to place your autos in the same room as your flowering feminized plants, meaning your autos will only get 12 hours of light per day.
- To save money: Running grow lights for 18–24 hours over a few months can get very expensive. If you want to grow autos on a tight budget, you might want to use a 12hr light cycle instead.
PERFORMING SOG WITH AUTOFLOWERS
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.
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.
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.
A NOTE ON LIGHT SPECTRUM
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.
As you might recall from science class, when you shine a light through a prism, it is broken up into different colour spectrums. Plants, which depend on light for photosynthesis, respond differently to these different spectrums. Like with a photoperiod cannabis strain, we recommend sticking to the following light spectrums:
- 6500K blue light during veg: Blue light spectrums have been shown to encourage vegetative growth, helping cannabis plants grow short and stocky while minimising stretching.
- 2700K red light during flowering: Red light spectrums are ideal for bloom because they encourage budding and a little bit of stretch, encouraging your plants to produce big, dense flowers.
EXTRA TIPS FOR GROWING GREAT AUTOS
If you’re new to the world of autoflowers, follow these simple tips for a better harvest:
- Pick a high-yielding auto: Not all autoflowers are made equal, so be sure to pick a high-yielding strain if harvest size is important to you.
- Plant in your final container: Up-potting cannabis plants always causes stress. Since autoflowers can go from seed to harvest in as little as 8 weeks, it’s best to avoid this kind of stress and always plant your seeds straight into their final pots.
- Use an airy growing medium: This helps stimulate root and foliage growth.
- Use LST: If you want to train your autoflowering cannabis plants, only use low-stress techniques. High-stress techniques like fimming, topping, and supercropping will end up doing more harm than good.
Best Light Schedule for Autoflowers
Unlike photoperiods that need at least 12hrs of darkness to trigger flowering, autoflowers automatically are in the flowering cycle from the seedling stage. They start producing buds based on age thus they don’t depend on darkness to start the flowering cycle.
Tip: Light cycles are used to simulate seasons in nature, more light = summer, more darkness = winter.
1. What is the best light cycle for autoflowers?
Most growers agree that the optimum amount of light to give autoflowering strains is somewhere between 18-24 hours of light a day. As a grower you should adjust the light depending on the cultivar you’re growing.
There are basically three life cycles aka Light schedules: 24/0, 18/6 and 12/12 (the first number is hours of light, the second is hours of dark). You can always adjust the cycle as long as they are receiving more than 12 hours of light a day (to achieve the best results). An example would be 19/5, 16/8, 22/2, etc.
Having that in mind, there are growers experimenting with schedules like 6/18 but if you’re new to growing you should stick to the basic schedules mentioned above.
2. Do autoflowers need darkness?
There are growers who believe autoflowering plants need a dark period and won’t be as healthy if they get a 24/0 light schedule. There’s no real evidence of that but there may be exceptions. Also have in mind that a 24/0 will lower humidity, increase temperature, and increase the light bill.
Schedules like 18/6 or 12/12 will save you electricity and if the few hours of darkness indeed help the plant to grow better, it’s a win-win. We recommend starting with an 18/6 light cycle and if you see your autoflower has the potential to grow more, you can always try again in the next cycle.
3. 24/0 Light Cycle
Plants usually grow faster when they get more light. This schedule is a good choice if you live in a cold climate, keeping the lights turned on 24hrs a day will keep your plants warm.
Obviously, this is the easiest light cycle as you don’t even need a timer, just turn on lights until harvest.
• Doesn’t require a timer.
• May result in the best yields.
• Uses more energy, can get expensive.
4. 18/6 Light Cycle
This is the most common cycle for autoflowers. You’re providing enough light for your plants to develop and a few hours of dark for them to rest, encouraging healthy growth. This can be good in hot climates.
You can leave your lights at night and have them turn off during the 6 hottest hours of the day. By using this schedule you’ll be using around 25% less electricity, which adds up to be a good economy at the end of every harvest.
A lot of growers who have experimented with 24/0 and 18/6 light cycles say they didn’t notice any major difference in final yield. The only minor inconvenience with this schedule is having to buy and adjust a timer. They cost around 10 bucks so it shouldn’t be a problem at all.
• Allows your plants to rest.
• Uses less electricity, allowing us to save on electricity.
• Can help lower temperatures and increasing humidity in hot climates.
• Requires a timer. This shouldn’t be a problem at all, as this is the first thing you should buy when growing indoors.
5. 12/12 light cycle
The 12/12 schedule is normally used for photoperiods. It can also be used for autoflowers but it’s not that popular. Normally growers give autoflowers this light cycle when they have them growing in the same tent as photoperiods. By giving your autos 12/12 you’re not using them to their full advantage.
Because your plant is getting less light each day, it isn’t able to make as much energy to promote growth. It will underperform compared to the other light cycles, that being said, you can grow them just fine if you don’t mind reduced yields and an overall smaller plant.
6. In Conclusion
There isn’t really a proven best light cycle. Before going for any light cycle, think about electricity costs and the climate you’ll be growing in. If you are in doubt, start with 18/6. This cycle is the most used and should work for all autoflowers.
When growing outdoors you have to work with what you have as you can’t control the sun (obviously). Outdoor growers should be aware that with the change of seasons the amount of daylight may increase or decrease but autoflowers should grow fine in all seasons.Unlike photoperiods that need at least 12hrs of darkness to trigger flowering, autoflowers automatically are in the flowering cycle from the seedling stage. The ]]>