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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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114 thoughts on “Marijuana Flowering

  1. melmel32 says:

    ok. we took cuttings off our plants that are growing outside…they are indivieually planted and now starting to grow buds what should we do? cut em off? leave em?

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    Rating: -1 (from 1 vote)
  2. christina says:

    Ok i have a plant that i have been growing since early september and it is still not flowering. i kept the light on it up until a month ago and niow im doin the 12 and 12 and i stil see no sign of flowering… but the plant is continueing to get full and grow tall what else can i do to make it start to flower

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    Rating: -1 (from 3 votes)
    • Kc says:

      Ive read that you canput your plant in complete darkness for 24 to 48 hours to get the plant to understand that its time to flower.

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      Rating: +3 (from 3 votes)
    • sean says:

      i have sorta same issue the ladie is imported skunk never had aprob with growth or fert burn but only one doesnt show turning signs even after a week

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      Rating: 0 (from 0 votes)
    • sadmad70 says:

      try adding some potash to it if its in soil.

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  3. #1closetgrowah says:

    floweering is the most exciting stage..but u must be patient..and caring and ur plant will give back!

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    Rating: +2 (from 4 votes)
  4. mark says:

    first timer ,My plants are outside and starting to flower do you trim leaves and fertalize they are about 6ft,looking to promote bud growth!!!

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    Rating: +1 (from 3 votes)
  5. Sammii says:

    Hi! So i have a nice girl not sure how old but has been in 12/12 for about a week now. She is flowering already. I had a reflector cuz my light is facing the wrong way and it fell on her and broke a stem…. will this kill her? Also what kind of light should i use? What nutrients should i use??

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    Rating: +4 (from 4 votes)
    • bluebuds says:

      no she will be fine prop her up tie her down and it might actually create bigger buds

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      Rating: +2 (from 2 votes)
  6. dang ol stoner says:

    …Perhaps the one major advantage Alaskan growers have is ready access to high-nutrient soil. Soil in and near river banks is particularly high in nutrients….
    That’s how they grow those giant vegetables at the Alaska State Fair!!!5

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    Rating: +1 (from 3 votes)
  7. dang ol stoner says:

    …Oh yes, almost forgot…Make sure the walls have insulation!
    Nothing kills plants faster than a sudden burst of arctic chill!!
    I understand the folks living near mountain passes and open plains regions are particularly susceptible….

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  8. dang ol stoner says:

    To post # 44…
    If you’re in Alaska, you’ll probably want to grow indoors. Growing outdoors is particularly challenging in your region. Best idea is to grow in a greenhouse or greenhouse-like apparatus with windows that have blackout shutters. This will allow you to have darkness for 12 hours even as you near the summer solstice. Having lived in Alaska for a while, I know for a fact that blackout shutters are not in short supply…everyone has ’em!!!!

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  9. dang ol stoner says:

    I have a dumb question…Is it possible to grow a plant from a bung ball from the dealer? Or will that not have any seeds in it?

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  10. BustazGrowroom says:

    as long as the room stays over 45 degrees farenheit, the plant’ll handle it

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    Rating: +2 (from 2 votes)

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