Grow Room Light Cycle Interruptions

Rambo May 30, 2017 Comments Off on Grow Room Light Cycle Interruptions
Grow Room Light Cycle Interruptions

Grow Room Light Cycle Interruptions

Indoor growers use light cycle manipulation to trigger cannabis plants to flower or stay in a state of vegetative growth. This is basic indoor growing 101 but growing cannabis indoor can be tricky and sometimes things go wrong.  If your light cycles are interrupted it can be disastrous and you need to know how to fix your mistakes when possible.

If you screw up and set a timer wrong, accidentally unplug a cord or a light bulb burns out, you and your plants could have a real problem. I’m sure you’ve never done such a thing but even the most careful grower can’t control power outages. I’ve experienced nasty winter storms that created power outages for days on end.

I don’t know about you but I can’t count how many times I’ve accidentally set my alarm clock for 6 p.m. instead of 6 a.m. Luckily I wake up on my own about 7 but cannabis plants don’t wake up on their own. Growing cannabis indoor requires following strict schedules of lights on and lights out. You are responsible for getting them to bed on time and up in the morning and you must be punctual. 

If you want your seedlings or clones to grow into strong healthy plants with huge bud producing potential, keep the lights on between 18 and 24 hours each day.

Grow Light TimerWhen your plants have grown enough that you are ready for them to start flowering and producing buds, change your grow light timer so your plants experience 12 hours of light and 12 hours of complete darkness for each 24 hour period.

For more details on light cycles and how they work check out “Light Cycles and Flowering Cannabis.”

When your light cycles are interrupted, even just a little, it can cause big problems for your plants. This can potentially result in huge reductions in your harvest so you need to know how to minimize the damage.

Extra Hours of  Light in Vegetative Cycle = No Problem

Cannabis plants actually grow quite well with 24 hours of light and a little extra usually doesn’t hurt.  If you are running a veg cycle of 18 hour lights on and 6 hours lights off, it’s not the end of the world if they don’t turn off on time. When you notice your mistake wait until the time of day the lights are supposed to turn off and make the correction.

Atmospheric ControllerThe only caveat is if you’re atmospheric control systems is not automated. Your equipment may not be set to run these extra hours and you could potentially have some serious overheating problems.

Pro Trip – Make sure the equipment that regulates temperature and humidity like vents and fans are always turned on by an atmospheric controller and not a timer.

Extra Hours of Darkness in Vegetative Cycle =  Problem

Cannabis plants are triggered to begin flowing when the hours of daylight begin to decrease or more specifically when the hours of darkness each night increase. This happens naturally outdoors because the sun sets earlier and the nights grow longer after the summer solstice. Long hours of darkness can happen all at once in a grow rooms. If the lights don’t come on as planned, your plants could be in for some trouble.

Prolonged periods of darkness signals plants that it is time to begin flowering. This can happen whether you are ready or not. If you are ready to begin flowering, then no problem, just move directly into a 12/12 light cycle. On the other hand, if your plants are still smaller than would be ideal, you could have problems.

Once you realize your mistake, get your lights back on as quickly as possible. Do not wait for the appropriate time of day to turn the lights back on. Leave the lights on until the timer would normally turn them off, assuming you had stuck to your light cycle. Now resume your original veg lighting cycles.

If there is a power outage, don’t wait for the power to come back on. Find a way to bring as much light as possible into the room. Most small generators probably won’t have enough power to run much of your grow room. Don’t try  to power your 1000 watt HPS lights and climate control systems. Substitute fluorescent bulbs or even a camping lantern if that is all that is available. You don’t need to provide enough light to make your plants grow, just enough to make it not dark.

What happens next really depending on the strain and how long the lights were off.

Your plants may simply return to their vegetative state or they may begin to flower. If they begin to flower it may be just enough to show their sex before they return to a vegetative state. In either case you might be in the clear.

There are also two worst case scenarios.

Scenario 1. Your plants may continue to flower for some time while putting on some vegetative growth. When you eventually switch to a flowering cycle the buds may not fill in but instead leave you with a small harvest of airy buds.

Honda GeneratorScenario 2. It may appear to have weathered the storm when in fact your plants may have a surprise waiting for your down the road. Plant stress can be caused by light cycle interruptions and has the potential to turn your female plants into hermaphrodites that grow male flowers. If this goes undetected, as it often does in large garden, you could find yourself with a harvest of small seed filled buds. When accidentally smoked, well, we’ve all been there.

Pro Tip – Consider having a small generator and backup florescent lights already hanging in your grow room. You won’t need much power for climate control equipment because your emergency fluorescent lights don’t produce nearly as much heat.

Extra Hours of Light in Flowering Cycle = Problem

Flowering cannabis plants need their sleep. If the 12 hours of darkness is interrupted with light, the signal to flower is turned off. The sooner this can be corrected with 12 hours of uninterrupted darkness the better. Once a plant is fully in the flowering state it is very difficult to coax it back to fully vegetative growth but you can still cause plant stress which may lead to hermaphrodites and seedy buds.

Even just a little light leaking into a room through a vent or around a door frame can be enough to cause problems.

Pro Tip – To test a room for light leaks, close yourself in the room with the lights out. Wait for 10 minutes with your eyes open so they adjust to the darkness. If you can see your hand in front of your face you have a light leak that needs to be fixed.

Extra Hours of Darkness in Flowering Cycle = No Problem

Extra hours of darkness during the flowering stage should not hurt the plants as long as it doesn’t last for too long. 

In fact some growers give their plants a full 24 hours of darkness or more as they switch from veg to flowering. It’s possible this gives the plant a little extra signal to begin flowering. I haven’t done the research to see if this is really beneficial but from experience I can tell you it’s not necessary.

When you discover the problem, leave the plants in the dark until the light cycle would normally begin.This should be a least a full 12 hours of darkness.

Even when you know what you are doing, growing indoor can be complicated. One mistake can set you back months or destroy an entire cycle. Trust me, there are plenty of opportunities to make mistakes. Learning how to grow indoor is a journey. Learning the best way to run your particular grow room can take years. Learning to avoid mistakes and how to correct them when possible takes time. Nothing complicated is mastered overnight but I hope this information will help you.


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