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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.

Growing autos? Click here to learn all you need to know about the right light schedule for autoflowering cannabis strains.

Best Light Schedule For Cannabis In The Flowering Stage

The majority of cannabis plants are photoperiodic, this means they depend on a 12/12 light cycle to flower. It’s crucial you provide the correct light cycle so your plants start to flower, although depending on the strain this can change, autoflowering strains start flowering automatically and don’t depend on light.

Cannabis plants in the flowering stage have already grown their branches and main cola, and are ready to put on weight in the form of buds.

Failing to provide them a good amount of light in this stage will result in airy buds, low yields, and your plant can become weak and unhealthy.

1. What Is The Light Cycle In Flowering Cannabis?

In the flowering stage, the amount of light your cannabis plants receive will influence on the quality, density, and yield of the buds. This means the buds will produce more resin and grow denser the more light they receive, resulting in a higher yield.

The most common light cycle for the flowering stage is 12/12.

This is because cannabis starts flowering when they receive at least 12hrs of darkness, while still needing the maximum amount of light possible to produce buds.

Our days only have 24hrs, so after 12hrs of darkness, the maximum hours of light we can give them is 12hrs.

There is no other light cycle to flower cannabis as they need as much light as possible, giving them less than 12hrs per day will result in lower quality and yield.

2. Light Cycle For Flowering Cannabis Outdoor

Photoperiodic Plants

When flowering outdoors, you have to be really careful and plan ahead. As you may know, every season has a different light cycle and this will determine how long your plant grows before starting to flower.

To give you an example, cannabis outdoors in California only flowers from September to March. So if you were to cultivate a cannabis plant starting in April it would grow for 5 months before starting to flower, in September, resulting in a huge plant.

If you want to avoid this, you can apply light deprivation techniques, this consists of using a black tarp to prevent light from reaching your plants.

This is used by all farmers, independent of the kind of plant they’re growing, the downside is you will need a greenhouse to be able to do this, as you need to block all light from coming in and this can be really hard to achieve without a structure to firmly hold the tarp.

Autoflowering Plants

With autoflowers you won’t have any of these problems. Autoflowering cannabis doesn’t need a vegetative stage per se, it will grow and flower depending on age.

This means it’s way easier to grow them than photoperiodic plants. A really good tip is to search on the internet the amount of light you will get on each month and plan your harvest accordingly, your plants can benefit from the extra hours of light.

Even though autoflowering cannabis can flower properly all year long, it can slightly improve the quality and yield of your harvest.

3. Light Cycle For Flowering Cannabis Indoors

Photoperiodic Plants

As said above, photoperiodic plants flower in a 12/12 light cycle. When growing indoors we keep it the same, although it can be easier to flower indoors because you don’t have to plan ahead.

When you feel like your plants have grown enough, you can simply change the light cycle from 18/6 to 12/12 by adjusting your timer.

It can take a couple of weeks for your plants to enter the pre-flowering stage and show signs of maturity (pistils or pollen sacs if they’re regular seeds), but soon you’ll see beautiful buds forming.

Autoflowering Plants

For autoflowering plants, there’s actually not much to do. They flower from seed in a vegetative light cycle, by providing an 18/6 light cycle from seed, your plants will go through all their cycle: seedling, vegetative and flowering without having to change anything other than the nutrients mix (if it’s required).

If you’re wondering why this happens, it is because automatic cannabis is a hybrid cross between Ruderalis and Indica or/and Sativa.

By crossing with Ruderalis, cannabis strains can have its characteristic of automatic flowering.

4. In Conclusion

Just like in the vegetative stage, when in the flowering stage your plants need the proper amount of light if you want your plant to develop to its maximum. If they don’t get the amount of light they need while flowering, the buds won’t develop properly and won’t produce the maximum amount of trichomes they can, resulting in lower yields and buds with less quality.

Your plants can also get weak and have a higher chance of being attacked by pests or diseases. To avoid this, always plan ahead when growing outdoors and get informed of how the seasons are in your city, including not only the amount of light but also humidity and temperature.

If you’re growing indoors, be sure to provide a good growing environment and especially a good amount of light and the correct light cycle.

The majority of cannabis plants are photoperiodic, this means they depend on a 12/12 light cycle to flower. It’s crucial you provide the correct light cycle so