cannabis not flowering

What To Do When Your Homegrown Cannabis Won’t Flower

Successful breeders know that getting cannabis to bloom is a strategic process. Most bloom issues are caused by a failure to manage the light your plant receives. There are some basic step by step things to do and check if your plant is not flowering. Worst case? Only grow autoflowering varieties.


It is always exciting. You have set up your home-grow op. You have planted and germinated your precious seeds and the little green sprouts have finally turned into real plants.

But. Then. There. Is. No. Flowering.

We all know that without flowers, there are no buds, no payoff.

No need to panic though! It is actually a common enough phenomenon. The following is an easy-to-fix checklist of common problems that interfere with efficient bloom and bud production.


Cannabis is like any other plant. It needs spectrum energy to grow. When planted outdoors, cannabis follows a seasonal cycle in spring and summer. Flowering generally occurs in late summer. It is also triggered by the summer solstice (June 21st). After this date, days begin to shorten gradually. Longer nights are thought to trigger blooming. Blooming usually starts in early August.

If you are growing indoors, obviously the lighting cycle is man-made. If you are not successful in getting your plant to bloom, the first culprit is probably the light. You will need to tweak your setup to make sure that it gets the right kind and temperature of light for the right amount of time.


Cannabis growers don’t need to be electrical engineers. That said, there are some basics to master when growing this plant. Blue spectrum light is best for vegetative growth. Red spectrum light is for flowering.

Particularly if growing indoors, investing in a red/blue spectrum LED light is one way to handle this issue. However, for those who do not want to invest in LED, merely changing the colour of the lightbulb at the right time in the grow cycle will do the trick.

Some growers leave their lights on 24/7 during the vegetative grow state. If and when the plants begin to show signs of stress, lessening the amount of light they get will help. 6 Hours of darkness is usually recommended.

Once plants get to a healthy size, growers can actually force the plant to flower by exposing it to 12 hours of red light and 12 hours of darkness. Be aware however, that even the smallest amount of off-cycle light during this process can stop the flowering process. Some people claim that a random flashlight beam can halt the process. Others feel that if lights are left on when they should not be for about a day, this should not adversely affect the growth. However, if the plants are left exposed to several days of extra light, be aware they will probably revert to a growing rather than flowering phase and you will have to coax them back.


Different cannabis strains mature and flower at different rates. This can to some extent be manipulated by indoor growers who match their lights to ideal growing situations for their personalised nursery. However, on top of this, it is also good to know your plant’s tendencies. Indicas will flower between 45 and 65 days. Sativa dominant strains take a little longer. They normally flower between 60 and 90 days.


If your plant still refuses to bloom, there is a very good chance that you have the wrong type of cannabis plant. Only female plants make buds. Male plants only make pollen sacs. Because these can also pollinate your female plants, reducing yields and creating seeds, many growers discard male plants immediately.


There are some types of cannabis that are known as “autoflowering” varieties. This means that they will automatically start flowering, no matter how much or what kind of light they get. This is also one of the best reasons, particularly for beginners, those on tight budgets and indoor growers, to buy seeds from an established breeder.

Getting cannabis to flower properly and at the right time is usually a matter of exposing it to enough and the right kind of light

Why Won’t My Cannabis Plant Grow Buds?

Why isn’t my weed plant growing buds? How do I get it to start flowering?

Short Answer: Cannabis plants only make buds when they are female and in the flowering stage of life. Otherwise, cannabis plants don’t make buds.

To get cannabis to start making buds:

  • Wait until plants are at least 3-4 weeks old from germination before initiating the flowering stage (they won’t start making buds before that)
  • Make sure the plant is female by looking at the preflowers (if plant is male, it won’t make buds)
  • Initiate the flowering stage by giving plants 12 hours of complete darkness every night. Most indoor growers accomplish this by putting grow lights on a timer with a 12/12 schedule, while outdoor growers typically wait for the nights to naturally become long as summer goes on (which initiates the flowering stage naturally)
  • Buds should start forming in 1-3 weeks as long as the plant is getting uninterrupted darkness for 12 hours every night.

Long Answer:

Cannabis plants do not start making sex-specific parts like buds until they reach the “flowering stage” of life. If your cannabis plant is growing without making buds, it means that it’s still in the “vegetative” stage of life, or the cannabis plant isn’t female.

Vegetative Stage – “Child” stage – plant grows just stems and leaves with no buds

Flowering Stage – “Adult” stage – plants starts growing sex-specific features like buds or pollen sacs.

Whether growing indoors or outdoors, the stage of your cannabis plant is usually determined by light schedules.

So before cannnabis plants start flowering, they are in the vegetative stage which means the plants only grow leaves and stems, with no buds like this:

First stage of Life – Vegetative Stage
(grows only leaves & stems – no buds)

A grower can tell when the vegetative stage has ended because the plant starts growing gender-specific parts in addition to leaves and vegetative growth.

In the second stage of life, the flowering stage, female cannabis plants will start to make buds (flowers). Male cannabis plants will only make pollen sacs (no buds) and are usually discarded by growers.

Second stage of Life – Flowering Stage
(plants start growing gender-specific parts like buds and pollen sacs)

Most growers only nurture and keep only female cannabis plants, since female plants produce buds that contain high levels of THC and other cannabinoids.

Male cannabis plants do not produce buds, only pollen sacs, and can also pollinate your female plants (which reduces yields and causes buds to have seeds), so most growers get rid of male cannabis plants immediately.

Cannabis plants grown outdoors will naturally enter the flowering stage in the fall as the days start getting shorter.

When growing cannabis plants indoors, the grower usually needs to artificially change the light schedule to get plants to start flowering (producing buds).

There’s an exception!

The exception to this rule about light schedules is auto-flowering (ruderalis) strains of cannabis, which will automatically start flowering on their own regardless of what light schedule they’re kept under. Most auto-flowering plants start making buds around 3-4 weeks after germination, though some strains take a little longer.

Cannabis Light Schedules (What Makes Cannabis Plants Start Producing Buds?)

Why Won’t My Cannabis Plant Grow Buds? Why isn’t my weed plant growing buds? How do I get it to start flowering? Short Answer: Cannabis plants only make buds when they are female and in