What To Do When Your Marijuana Plants Won’t Flower

It is a well-known fact that marijuana plants use light as energy. Light schedules play a huge role in determining the stage of life of your plants.

Marijuana plants will not begin producing buds until the flowering stage.

During the vegetative stage, your plant is just a baby, so it is only growing leaves and stems with no buds.

Read the article to find out why your plants aren’t flowering.

Vegetative vs. flowering stage

cannabis vegetative vs. flowering stage

Special organs inside leaf cells called Chloroplasts secure the red and blue light from the visible spectrum of light and use those to start photosynthesis.

During photosynthesis, plants take certain elements from air and water to produce sugar while also releasing oxygen.

A marijuana plant growing outdoors will do just fine in lots of sunlight and begins flowing in the fall.

But when it comes to big, compact indica buds, the plants grown indoors require about 40 watts of HPS or MH light per square foot.

However, sativa buds require around 60 watts. In the first stages of growth, you can use both the HPS and MH lamps.

You will need to change the light schedule for indoor growing to get your plants to start flowering.

HPS grow light during vegetative stage
HPS grow light

There’s no way around this process!

Fluorescent light is fine for the vegetative state and the flowering period.

When your plant is in the vegetative state, you will use cool, white fluorescent lights and when it reaches the flowering state, use warm white fluorescent lamps.

HPS light is good for generating flowers when the plant is in the flowering stage.

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    Why are my marijuana plants not flowering?

    If you shifted the light schedule to 12 hours of darkness/ 12 hours of light and a few weeks have passed with no flowering, there are 3 possible causes.

    Either your grow room has some light leaks, the lights were on for too long or the light may have been on at the time there was supposed to be darkness.

    Flowering problems and solutions

    Forcing your plant to flower

    Do your best to stick to the proper light cycle. If you need to go into the garden during the dark time, use a green light.

    Fluorescent burn the leaves

    If you are using fluorescent lights to grow, then it is necessary that your plant stays at least a few inches away from the lights.

    So long as this rarely occurs little harm will be done. If you experience light burn frequently, you can wrap a wire barrier around the tube to makes sure the leaves never touch the light.

    Fluorescent lights
    Using fluorescent lights on marijuana plants

    What if the darkness or light cycle is disrupted?

    Darkness Cycle:

    Let’s say the lights were accidentally left on for a full day, then this won’t be too much of a problem.

    Now, if the lights are on for a few days consecutively at the beginning of the flowering period, you may notice your plant returning back to the vegetative stage.

    Your plants are not as damaged by too much light when they get close to being fully developed.

    When the light schedule is thrown off, get it back on track quickly to avoid further problems.

    Light Cycle:

    When the lights are off for a day or two, you will notice the buds are maturing faster and that is okay.

    Just turn then on again and carry on with your regular schedule until they are fully matured.

    Both Cycles:

    So, if the light are turned on and off intermittently your buds will become scrawny and could potentially become hermaphrodites.

    Check out our articles on hermaphrodite plants to learn more.

    If you need to, just use a timer to make sure the light schedule is constant.

    No flowers on indoor plants

    So, your indoor plants are not flowering? Offering your plants 12 hours of darkness a day without disruption for 5 days will producing flowering.

    Depending on the seeds you use, you may need to continue this cycle for longer.

    It is important that this schedule is followed exactly the same each day. It’s best to have a timer for your lights to prevent unexpected mistakes.

    Remember, to make sure your plant thrives during the flowering stage you need to adhere to the light schedule.

    Proper lighting is essential to your plants health. Too many mishaps with the light cycle could result in damage to your plants.

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    FAQs About Why Cannabis Plants Are Not Flowering

    Why is my cannabis plant not flowering?

    If you shifted the light schedule to 12 hours of darkness/ 12 hours of light and a few weeks have passed with no flowering, there are 3 possible causes: either your grow room has some light leaks, the lights were on for too long or the light may have been on at the time there was supposed to be darkness.

    What are some ways to trigger my marijuana plants to flower?

    Always follow the proper light cycle and make sure your plant stays at least a few inches away from the grow lights.

    Have you had problems with the flowering of your marijuana plants? Please share your experience or leave questions below!

    Happy growing!

    Robert

    Avatar for Robert Bergman

    Robert Bergman

    Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]

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