Growing marijuana indoors, you need to know the best schedule to set your timer for the Vegetative Light Cycle to come on and turn off. While the marijuana plants are in the vegetative growth stage they require a minimum of 12 hrs per day of light, preferably Metal halide grow lights, which produce the white/blue color light spectrums plants crave to grow healthy. There are growers that use 18hr or 24hr light cycles as these 2 are the most common ways of growing indoor marijuana plants. I will explain the most common light cycle and the more advanced, energy saving method I use to grow healthy mother plants.

24 Hour Light Cycle for Marijuana

The 24 hour light cycle is by far the most common way of growing cannabis plants indoors, in the vegetative, clone or mother plant stages. You don’t even need a timer for this as the lights remain on 24 hours a day, never needing to be turned off. You can also set a timer to come on for 18 hours and off for 6 hours, which is also considered a “24hr cycle option”. By doing this, you are wasting electricity, and burning through bulbs much faster than you should be, all costing you more time and money that you shouldn’t have to worry about. The 24 grow light cycle will cause the mother plants and clones to grow at such a fast rate that it may become a problem with space and light.

Advanced Marijuana Growing Light Cycle

The advanced light cycle for marijuana growing will save you time and money, allowing for more quality plants and marijuana buds. This grow light cycle will also save wear and tear on your Metal Halide or Grow Bulbs you are using. Here is a schedule to follow for an advanced growers vegetative light cycle:

Lights used in the Vegetative Growth Stage

This light cycle is 13 hours on and 11 hours off each and every day. Simply set your digital timer to come on for 12 hours, off for 5.5 hours, on again for 1 hour, then off for 5.5 hours.

By doing this you will give the marijuana plant enough light per day for it to continue growing in the vegetative stage, as well you are saving close to 50% in your electricity bill. This vegetative light cycle is highly used by all of my veteran medical marijuana growers.

  • Mad Lyrics

    Hello Dizzle,

    Would you say that the advanced growing light cycle (13ON/11OFF) can be an efficient solution for someone who would like to get some plants outdoors early in the Spring, by mid-April for instance, in order to avoid them to go into flowering rather than growing?

  • Terry

    I’m doing a set up how do I set the water timer and how aften do I have to water them

  • black light??

  • Coupe

    Do I need a heat light with my black light for the vegg step?

  • it should still produce the same amount of yield. the advanced light cycle forces the plant to flower faster due to its way of confusing the plant. its not a major difference as some strains are stubborn and take the same time no matter what you do to force them. turning on/off doesnt hurt the light.. ive been using the same ballasts for many years. thousands and thousands of “on/off” switches, never had any issues and the bulbs still produce plenty of spectrum.

  • Steve

    I’m trying your advanced light cycle with 3 plants and a 250W MH light and grow tent.

    Can you tell me if yield using both advanced veg and flowering cycles will produce less bud or just as much or more?

    you also said it would save time and money. How so with time? Doesn’t it take just as long to grow?

    The lifecycle of the actual MH light. All this turning on and off is ok. Some people said that this would wear the light out faster. I personally don’t think so and since you’ve done it before, you would know.

  • Steve

    I think he means hermaphrodite

  • yes u can switch to a 24 hr cycle. what is hermies??

  • santa maria

    hey brother,

    can i change the cycle of the light on my plants that are already 18/6? this technique sounds really good.. also some told me that it can give you hermies? is there a specific name for this ?? i’m sure interested to read more about it…


  • yes u will be fine

  • j

    i was planning to grow them only up to about 10-12 inches. is that tall enough? and will the plant be sorta mature enough to flower at that height?

  • every strain out there is 100% different. some flower in 6 weeks, some in 12+. veg time is soley up to the grower. how long and how big do u want them to be? i like to flower some immediately after cloning, and others i let grow 4 weeks or so. depends on what strain and what im trying to accomplish.. its a must that u KNOW your strain!!! otherwise u have no idea what it wants or needs

  • j

    dizzle, what is the average time(weeks) it take for vegging stage? and how long does flowering stage take?

  • bob

    worded the sentences a little wrong. meant to say your recomendations for lighting on the veg and flowering stages will work for both soil or hydro.

  • bob

    thanks dizzle, so just your recomandations for lighting durning the veg and flowing stages is for both hydro and soil. BY the way great site with great info. Im sure ill will be htting you up with more questions. Thanks for such a fast responce.

  • the veg stage in soil is basically the same as hydro. hydro may be a few days or a week faster but nothing to worry about

  • bob

    dizzle does this apply for people growing in soil or just hydro?? Wont the veg stage be long for the soil growing?? Thanks for the info, new to this

  • just a couple weeks

  • Vol

    How many weeks to veg like this ?

  • yes i have found that this 1st keeps heat/temps lower, as the lights are not on constant. Also what im really starting to notice lately is that by manipulating the plant to wake up (lights on) and sleep (lights off) more times through out the day, this seems to have created a much stronger and healthier plant. less likely to get stressed. kinda like a militant sleep schedule. creates a tough soldier.. im still doing a ton of research on this subject, and will continue to update.

  • honeyoil

    Thanks for your post. I think you are saying that the plants will grow better with the advanced light cycle in veg. I have been using 24 hours of light in veg. Can you elaborate on how the advanced light cycle causes the growth to improve? Same (except 12/12) question for the advanced flower cycle. 🙂

  • once you transfer them to the veg stage. i choose to do so once the 4th set of leaves has started to grow.

  • George

    When are the plants in the vegetative growth stage and out of the seedling stage?