Gas Lantern Routine – Growing Cannabis User Guide

MichaelCannabis, Garden, Growing Cannabis, Marijuana, Organic25 Comments

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Growing Cannabis Plants Outdoor

It is possible to grow large cannabis outdoor year round using a simple technique called the Gas Lantern Routine.  This technique will also work great indoors or in another climate outdoors without frost.  Cannabis is a unique plant with multiple stages of growth; seedling, clone, vegetative and flowering.  A vegetating plant focuses on growing larger everyday to allow for more finished product.  The larger the plant the more potential harvest.  This vegetative stage can last anywhere from 2 weeks to 5 months.  The flowering plant stops growing in size and starts focusing on growing flowers or the buds that we smoke.  These buds are covered in trichomes which harbor the THC and CBD that gives us the healing effects of Cannabis.

In nature, Cannabis sprouts after the last frost then grows through the summer while the daylight hours continue to get longer.  June 21st marks the summer solstice, the period at which point the sun is at it’s peak and the daylight hours are the longest.  In San Diego this is from 5:41Am to 7:59pm, just over 14 hours of daylight.  Everyday after the summer solstice, the daylight hours begin to trend down 1-2 minutes per day.  A small gradual change but the plants do notice!

Flowering Stage Trigger

Sometime in August, and depending on the strain, the plant has detected the total daylight hours are approaching 12. In San Diego, on August 31 there is exactly 12:50 minutes of daylight.  The flowering period for Cannabis has a median of approximately 60 days.  However, after decades of crossing genetics, many growers have created strains that can be harvested at 45 days to 80+!  The flowering trigger is a rather small change in time.  If Cannabis in the wild receives approximately more than 13 hours of daylight, it will keep growing or “vegetating”.  Conversely, when Cannabis receives more than 12 hours of uninterrupted darkness, it is certain to begin to go into it’s flowering stage. Once Cannabis receives 12 hours of uninterrupted light, the plant hormones are triggered and the flowering stage begins. The detection of the flowering phase is not overnight, the process takes approximately 5-10 days depending on the strain.

Do not expose your plants to undesired light. Forgetting to turn patio lights off or any light exposure during dark periods is undesirable. When this occurs, the plant can produce hermaphrodite characteristics which are always undesirable. When flowering, keep your plants in total darkness for 12 hours!  Anything over a full moon’s worth of light is too much and will likely trigger those unwanted characteristics.

Gas Lantern Routine

The secret to the gas lantern routine lies in the 12 hours of uninterrupted darkness for plants to flower.  The trick however, is to be consistent because inconsistencies while growing cannabis are heavy promoters of hermaphrodite tendencies, most importantly light!  If you never allow your plant to reach 12 hours of darkness, it will not flower.  This phenomenon is rooted deeply in the Cannabis genetics and gives way to the gas lantern routine.  Turn the light on using a timer for 1 to 3 hours in between the night. You don’t have to use a powerful light either, we generally use 75 watt household bulbs. But make sure there is enough light to cover your entire garden, otherwise parts that don’t receive enough light will flower. For example, on November 4 the darkness period is between 6:30pm and 630am, making the midpoint around 12:30am.  This is your target time to to interrupt the plants, turn on the light for 1 to 3 hours, and viola!  You have successfully allowed your plants to stay in the vegetative state.  The Gas Lantern routine should be used anytime between August and April in Southern California; or applied in any scenario while the darkness period is less than 13 hours.

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Why use this method?

The gas lantern routine is highly effective for two reason; saving energy indoors and growing larger plants outdoors while reducing your carbon footprint.  When applied indoors, growers can cut their electricity cost 25-50%.  They have also reported better yields due to the increased rest for the plant.  Many believe this method is more natural than the traditional 18/6 Veg/Flower cycle.  This is because no where on Earth does landrace cannabis receives 18 hours of sunlight for a sustained period of time.  When using this method outdoor, your plants are able to grow larger more naturally using the sun’s energy.  Thus, reducing the need for high powered energy lights attempting to replace the sun’s power!  Fertilizer Guide!

25 Comments on “Gas Lantern Routine – Growing Cannabis User Guide”

  1. A lot of people are growing cannabis for medical reasons. I am sure they will love to know about this. Great idea for sharing this to everyone!

  2. I am using this method right now and my plants are very healthy. I’ve read of many people using this technique with great results. I’m running a 1000 watt metal halide in a cooled 4×8 tent. Using GLR, makes a difference of 150 kwh’s per month. That’s huge in savings compared to the way I used to grow. I use a 40 watt 24″ dual florescent fixture to do the interruption at night. I don’t use the HID for this. Using 18/6 with my HID at reasonable distances, I swear my plants looked exhausted after 16 hours and extracting the last bit of extreme yield isn’t the most important thing for my personal grow, anyway.

    1. Awesome thanks for sharing your Info. I’ve just started growing last April 2019 and was looking for ideas and now I have a pretty good idea on my next ops.

    1. Unfortunately I do not have any experience with auto’s, but from what I have read, they will flower no matter what once they reach a certain maturity level. If it starts to flower and you give it more light, you are most likely adding unnecessary stress. Let me know if you have any more questions.

      1. Hi Kerry! I did a little more research on this topic and talked to some auto growers. Auto’s will flower no matter what. You can’t stop it. If I may ask, why did you want to use the gas lantern on a auto in the first place? I hear a 20-4 light schedule is the way to go for auto’s.

        1. Hi wondering if it’s a good idea to change to gas lantern routine for a mother plant 6 months old to save power when and were I can please help appreciated

          1. Hi Luke,
            Thanks for the great question! For me it depends on a couple things. I’ll keep my answer short, but hopefully it helps! If you have any other questions, lmk.
            Is this is a strain that you continually grow? If it is, then I definitely recommend testing to see if you can take great clones, over time from that strain/mother on gas lantern. This is the only way to know if it can manage the reduced lighted hours. However if this is a one time mother, then I would recommend maintaining hours. Play it safe!

  3. Curious why you set the timer to turn on in the middle of the night rather than just turning them on before sunset for a few hours to extend the appearance of a longer day? Love the article and can’t wait to try this technique!

    1. Hi Scott! Although I usually error with more time, 1 hour of light in the middle of your plants sleep cycle should do the trick! But if you feel more comfortable with adding more time either before sun up or after sun set..this will definitely work as long as you meet your plants vegetative hourly requirements.
      I would also like to point out that sometimes one light bulb simply isn’t enough. For larger grows, more light is needed. I have witnessed situations where some branches are in full flower whereas others are still vegetating on the same plant. This simply means that those branches flowering were not receiving enough light to sustain vegetative growth. If you have reached this point, I would recommend letting your plant go into flower because revegging can sometimes promote awkward growth. Good luck!

  4. So if I were to germinate some seeds now and veg them outdoors (I’m in Santa Barbara) how would I proceed? Interrupt the dark every night for an hour until I am ready to flower? Or do I need to make lighting adjustments? How would the yield turn out?

  5. Clone growers don’t tell you they’re getting 20 or so hours of light when sold and a drop to 16 or 13 will trigger flowering always. I have made the mistake many times.

  6. This guy & his wife were given two plants by their kid…the kid had the plants on 20 hour lights for the last couple of days before putting them outside at his parents…they tricked themselves in July because of the lack of sunlight. I ended up transplanting them in a good soil mixture with some bat guano and they grew like monsters.

  7. When your plants have matured in Veg and they are ready to flip can you reduce total wattage to keep ac/elec costs down during the daylight portion of Gas Lantern?

  8. I have 2 clones purchased from a local shop. 2″ Rockwool cubes, about 8″ tall. (Tropicana Cookies and Nepali Pink)

    Plan is to harden and transition these to outdoors, here in Los Angeles, Mild climate, Early Nov–now.

    I plan to use ‘lantern method’ of lighting to break up the +12-hour darkness that would send the clones into flower.

    Any thoughts re the following?
    1. Best practice for transferring rockwool cube into soil. Bury the cube completely, or leave 1/2″ sticking up to breathe? Water the cube or the perimeter away from the cube?

    2. Large pots or in the ground?

    3. Can I maintain a sativa in veg state long enough to grow up a 10′ tall trellis? Will Lantern method work for this purpose?

    Thanks for the advice!

  9. Will I be able ot grow outdoors in Los Angeles using this method, or is it too cold to do this growing from Nov-Jan….? Thanks!

    1. Although small, some of my favorite grows have been Oct – Jan… and if the weather stays nice, even better!

  10. I’m confused. You write: “Once Cannabis receives 12 hours of uninterrupted light, the plant hormones are triggered and the flowering stage begins.” Isn’t the 12+ hours of uninterrupted darkness which triggers the flowering stage?

  11. When winter growing outdoors in suburbia, light pollution and cold are the biggest problem. I tried so I know. The stress from the cold will make your plants herm. When the temp gets down below 55F, the growth will stunt. I could not afford to run my greenhouse heater. Don’t even mention the light pollution; major fox tailing if your lucky enough to make it bud. Try some heating mats to keep the root ball warm and use black out tarps from HF if light pollution is a issue. All in all, I would stick to indoor tent growing during the winter. It gets too cold in Northern California during the winter unless you have a green house.

  12. I’ve used this technique for about 2 decades now and i get great results than if I used 18/6 as my lighting…….and it does save on energy…

  13. “When winter growing outdoors in suburbia, light pollution and cold are the biggest problem. I tried so I know. The stress from the cold will make your plants herm. When the temp gets down below 55F, the growth will stunt. I could not afford to run my greenhouse heater. Don’t even mention the light pollution; major fox tailing if your lucky enough to make it bud. Try some heating mats to keep the root ball warm and use black out tarps from HF if light pollution is a issue. All in all, I would stick to indoor tent growing during the winter. It gets too cold in Northern California during the winter unless you have a green house.”

    what if i leave the plants outside in the sun during the day and bring them into the house at night and set the timer for 1am ?

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