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Marijuana Flowering

Marijuana Flowering

If you want your marijuana plants to start pre-flowering just change the light cycle to 12 hours on and 12 hours of complete darkness. This convinces the plant that the days have got shorter and now is the time to flower.

Why does this work, well let’s think about how plants are in their natural environment. Marijuana like most plants start off growing from seeds in early spring, then go through their vegetative stages in the later stages of spring and all of summer and when fall comes and the days start to become shorter during fall/autumn there is less light and more darkness and this triggers the plans to flower, or bud. So when you are growing indoors professional growers move from a 24 or 18 hour vegging light per day to 12 hours on and 12 hours off.

pre-flowering female marijuana

Although, while waiting for marijuana to flower can seem to take forever, once your plants truly enter the flowering stage their growth rate can be stunning. Growth patterns and nutrient cycle timing and requirements will change. The vigorous vegetative growth will slow, stems will elongate and flower formation will begin rapidly at first before slowing. If you are growing hydroponically you should now be using a bloom or flowering mix of hydroponic nutrients. If you are growing in soil you should add a fertilizer that is high in phosphorous and potassium such as ‘Super Bloom’. Read more about marijuana nutrients.

Whilst in the flowering stage it is important that plants receive no light outside of their 12 hour day cycle. Any light received can confuse and stress plants leading to abnormal growth. Make sure the room is light tight. More information on marijuana lighting.

  1. Note that less than 12 hours light will reduce flowering speed and overall yield.
  2. Note that putting the lights on during the 12 hour dark period a number of nights in a row, even for a few minutes can revert the cannabis back into its vegetative growth cycle.
  3. Trick you can use a green light bulb in the grow room to help you work while the cannabis is in darkness. Green light will not affect the plants.
  4. Trick some growers will give their babies a full 36 hours of darkness to send the message that flower must begin. This usually decreases the time in which flowering begins.

These days you can also buy auto-flowering marijuana seeds that will start to flower after a certain number of weeks.

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From the forum

How to Grow Marijuana Forum - Growing Marijuana Indoors & Hydroponics

111 thoughts on “Marijuana Flowering

  1. weed wilLy says:

    MALE PLANT, OR A HERMAPHRODITE PLANT.. GET RID OF IT AS SOON AS POSIBLE, IT WILL FILL YOUR FEMALES BUDS UP WITH SEEDS. YOU COULD ALSO KEEP THEM FOR SEEDS, FAR AWAY FROM THE FEMALES, LIKE MAYBE YOUR ATTIC. MAKE SURE THAT WHEN YOU TEND TO THE MALES YOU ALWAYS SHOWER AFTERWARDS. YOU CAN EASILY POLLINATE YOUR FEMALES JUST FROM TOUCHING OR EVEN BEING IN THE SAME ROOM AS YOUR MALES…

  2. nathoz69 says:

    hi i got plants in a cupboard on 12/12 2 weeks into flowering what should i do with the light should i change the light times or leave it on 12/12 to get the best yield?

  3. Wayno thomas says:

    HI guys, My friend has a small one plant setup running a 400 watt MH, and soil based grow.. Its around 4 ft atm,but being ‘trained’ to improve light coverage.Its early flowering atm,hairs on most branch colas n nodes.He wants to kno if runnin the 400MH will be ok for entire flower or is it best to have the HPS also? Thanks.. SMOKEM

  4. Faithless Chick says:

    Kingy, I would start using bloom as soon as you turn them over to 12/12

  5. wendy says:

    my plants r about 5 weeks now im using flouresants about 3 42w each plant when going into flower i no i change to 2700 soft white but do i use more lights or will the 6 work and i would like to no if there are any light bulbs that would work light hps that dont need ballast

  6. kingy says:

    iv just turned 2 12\12,, what feed shud i start with been tols 2 use bloom after 4 wk ??

    • Charles Wooldridge says:

      Anything bloom. First week or two go straight water, then to bloom. This gets out the nitrate. And by the time you feed them in a sense they’ll be starving, which speeds growth too.

  7. Swedishsteel420 says:

    Hello world…
    I got 2 ladies at 3 months age… they are about 4-5 ft high.. about 3 quarter inch thick stems. I put them into flowering on an 8 am – 8 pm cycle. 2 weeks into the 12-12 cycle i still dont see any signs of trichs… im runnin 1 “life glo 2 20Wa” and 1 “flora glo 20Wa”tube… also i added a UV-B lamp after going into flower stage, since it seem they produce THC to protect from damageing UVB rays. Shuld i worrie, cause i think nothing much happen to em since i start the 12-12 2 weeks ago….

  8. farmer ted says:

    hey i started from seed 20 days ago,,its about 5 in tall with 6 good leafs and lots of smaller stating,,its bn on 24)7 lite,,, can i start flowering now ?

  9. skir says:

    k so i started mine with the lighting at about 18 on 6 off. how big should i let the plants get before i start the veg cycle, and what type of lighting should i use?

  10. slowpaya says:

    i start a lot of my plants 12/12

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