LED Grow Light

Why We Don’t Recommend 6/2 Light Schedule-Part I

We like to keep things simple. And that means sticking to tried-and-true methods. Weed that is growing outdoors enjoys long periods of daylight during vegging and around 12 hours of daylight and 12 hours of darkness during flowering.That is why indoor growers provide 18 hours of daytime during vegging and then switch to 12 hours to induce flowering.It works.

So obviously, we’re skeptical when presented with the completely different 6/2 light schedule. But we’re always willing to keep an open mind, so let’s take a closer look.

6/2 Light Schedule

A 6/2 light schedule means keeping your lights on for 6 hours at a time, then turning them off for 2 hours. You do this three times a day. This schedule is for vegging (or seedlings), but obviously not for flowering, which requires 12 hours of continuous darkness.

In terms of total amount of light, it is the same as the standard 18/6 vegging schedule (18 hours of light, followed by 6 hours of darkness). The light and darkness periods are simply broken up into 3 smaller chunks. Breaking the periods of light and darkness up like that has several advantages, though most seem to be anecdotal only. It also has some potential disadvantages.

We’ll cover them next, but overall, we conclude that you’re better off just sticking to one of the regular time schedules, like 18/6, 20/4, or leaving grow lights on 24 hours.

Advantages Of A 6-2 Lighting Schedule

Below are the three most commonly cited benefits of a 6/2 lighting schedule. Only the last one is a proven benefit, and it is one that most growers won’t really need. The other two might help a bit, but probably won’t make much of a difference to your grow overall.

Gives Plants A Rest Period

The advantage most often cited for the 6-2 schedule concerns the amount of light plants can process per day. Once a plant has reached its daily limit, it can no longer absorb any light and continuing to give it light after that point is simply a waste of resources.

Providing 2 hours of darkness after 6 hours of continuous lighting gives the plant a chance to rest and process the light it received during those six hours. When the next 6 hours of light begin, the plant is ready to process more light. In this way, you maximize growth throughout the day.

This sounds like a compelling argument, and it very well may be, but we have not found any proof of this whatsoever. In fact, we have not seen any reports of growers having issues with 18 hours of light being too long. Many even provide light 24/7 during vegging and it does not seem to have any negative effects.

Prevents Light Stress

This is another unproven advantage. After 18 hours (or more) of continuous light exposure, marijuana plants can start to show signs of stress. These include droopy leaves or leaves that curl upward and they appear near the end of the light cycle.

If you only have the grow lights on for 6 hours at a time, these symptoms of stress do not appear. It strands to reason that shorter periods of continuous light are less stressful on the plants. What is not sure is whether a little stress actually has any negative effect on the plants. Every indication is that it does not.

Gives Your Grow Tent A Chance To Cool Down

If you are having trouble keeping your grow tent cool, a 6/2 lighting schedule might be beneficial. By breaking up the 18 hours of running your lights, and giving them 2 hour breaks every 6 hours, you also give your tent 2 hours to cool down.

This means you won’t need quite as much air conditioning, ventilation, etc. You also won’t have to run those systems for 18 hours straight, which put less stress on your fans and other equipment.

To be continued…

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