The Flowering Stage of Marijuana Plants: What to Do

The flowering phase of weed is the time when all gardeners growing cannabis is excited about. After the flowering period is the harvest time. But before you get too excited, pay close attention to this stage of cannabis cycle. After the vegetative phase, marijuana will than about to enter the budding time. This is a crucial stage for the weed plants and the growers too. The sex of the marijuana plants can be determined during the flowering stage.

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You have to know the characteristics of males and females. If you do not want pollination to happen and you want to preserve the high potency of the weed strain you are growing, immediately pull out the male weed plants from your garden once you see them. Learn how to identify marijuana sex by clicking here.

When growing cannabis, requirements when it comes to light and nutrients will vary during the vegetative and flowering stages. These two factors will determine the rate of bud production and overall success of your weed growing project.

Light Requirements during the Flowering Stage of Indoor Weed Growing

During the flowering phase of growing pot indoors, supply the plants with 12 hours of light and 12 hours of the dark period. Do not put the lights on while the weed plants are on their dark period. This may cause stress on the plants, slow down the budding process and eventually affect the number of buds to be harvested.

For indoor weed growing, high-pressure sodium lamps are recommended. HPS produces more heat so position the light well so as not to burn the top of your marijuana plants. Fluorescents are also a good alternative for HPS lamps because it is cheaper and has low heat output.

Nutrients Needed During the Flowering Phase of Cannabis

During the budding time of cannabis, the plants need a high amount of potassium and phosphorus to increase flowering. The primary nutrients nitrogen, potassium and phosphorus are essential for the vegetative to flowering stage of cannabis growing in varying amounts. To promote stronger roots, prevent and correct other plant diseases, secondary nutrients may be given during the flowering phase.

If cannabis plants are provided with all the things necessary for their flowering stage, you can expect an abundant harvest, potency and quality buds from the marijuana strain you have chosen to grow. When growing cannabis, provide the plants with the right type and spectrum of light. Expose them to the right number of light and dark hours to ensure proper bud production. This is very necessary when growing marijuana indoors but not much of a concern when weed plants are grown outside.

A lot of beginners in the field of growing marijuana decide to switch their nutrient ratios rather early. Well, it may be the easiest things to do. However, keep in mind that at this point, your plants are still growing at the start of the phase. Even though it may be true that your plant requires more potassium and phosphorus, the fact still remains that it is still growing for several more weeks. Therefore, nitrogen is still very important.

If you end up depriving your plant with enough nitrogen at this very important stage, it may end up developing a deficiency. As it is nearing the harvest time, your plants will start to turn to yellow, with their health starting to decline. With this, it is often a good practice not to alter the use of your nutrient solutions until your plants clearly show clear signs of flowering. With this, you can start to see the pistils and stamens clearly as you change over.

Temperature and Humidity Requirements

As your plants enter the flowering stage during their growth, you may want to adjust the environment according to their needs. If you are not yet implementing them, you may want to change over to using sodium vapor lamps as they are reliable when it comes to emitting the spectrum of light which is ideal for cannabis plants in the flowering phase.

At the same time, you will also change the day/night cycle of exposure to light, thus shortening the total amount of time that your plant receives at this point. Some expert growers recommend the use of equal rations of light and darkness, given a 12: 12-hour cycle all throughout the entire day.

After starting this process, make sure that there are no interruptions whatsoever. Of course, you would not want your plants to be confused by allowing it to be exposed to light during their dark periods within the cycle. The interruption of illumination may also result in the plants to change back to a grow cycle, thus potentially inhibiting a good yield.

When it comes to temperature, you would want to make sure that the air temperature is changed between its light and dark cycles. As your plants are exposed to light, the air temperature should be playing around 68 degrees Fahrenheit and 77 degrees Fahrenheit (or 20 degrees Celsius and 25 degrees Celsius). This is the recommended temperature near the foliage, while a temperature of 68 degrees Fahrenheit or 18 degrees Celsius right at the roots.

Keep in mind that higher temperatures will also need higher carbon dioxide levels. When your plant is in their darkness cycle, you can also allow the temperature to drop down to a level of about 68 degrees Fahrenheit, or 18 degrees Celsius.

With humidity, your plants should be exposed only to a steady 70% level. By making sure of this stability, you can help in the prevention of any pest problems which may arise during this phase. At the same time, this is the best time for you to switch over to a nutrient solution specially designed for the flowering phase. As a reminder, again, make sure to avoid switching over just too early.

What to Do – Week by Week Guide

Your marijuana plants enter the flowering stage when some levels of uninterrupted darkness are provided to the plants. The moment you are ready for this phase, you need to give your plants around 10 to 12 hours of darkness, causing them to change from the vegetative stage, starting the flowering process.

On an average growth, the flowering phase usually lasts about 7 to 9 weeks. However, there are some sativa strains that could even take longer. Make sure that you research on your particular strain in order to know its flowering time before starting your own grow.

In order to make sure that your marijuana plants fulfill their maximum potential during this phase, it is very important to ensure that external factors including the type of light used, as well as the color spectrum you choose are great for your plant.

At the same time, it is very important that you give your plants with the nutrients needed while they are still in their vegetative stage because it will make sure that your plant grows to maximum size before entering the flowering period in order to make sure of the best yield possible.


During the first week of your plants’ flowering phase, they will require some special attention. This is because your plants need to be flushed off with the nutrients used during the vegetative phase. This is because they will be replaced with new nutrients that are necessary for the growth of the plants during the flowering phase. As a note, it is a usual scenario for plants to enter a shock in this phase as a result of a change in the nutrients taken, keeping an eye on your cannabis plants.


In the second week, your plants will begin to form little buds. You can start seeing the pistils, or the white hairs, starting to appear from the plant. This is a sign that you are growing a female plant, not a male one. At this point, it is very important to continue feeding your plants with nutrients needed in this phase in order to help it attain its optimum potential. By giving your plant the specific nutrients needed at this phase, you are ensuring that it will not encounter deficiencies which may impact the quality of buds during harvest time.


During the third week, you will notice that your plants are still growing. At this point, your plants should already be about 25-50% bigger than what they used to be at Week 1 of the flowering stage. You will also see some trichomes and resin glands on the flower, giving you a small glimpse of what you can expect with your plants. The smell will just be tolerable at this point, with the plant continuing to grow during this week.


As your plants start to enter the fourth week of the flowering phase, the vegetative growth will have already ended completely, and your plant can now focus entirely on flowering. Because of this, you can start seeing big changes in the appearance of your plants all throughout the next weeks. For one, you can observe that the buds will start to show on different bud sites all over the plant. For the next days and weeks, you will also notice the density of the buds continuing to increase as the harvest time draws even closer. The odor, at this point, will become more obvious as the plants start to produce more trichomes.


As you enter the fifth week, there will be a noticeable increase in the production of buds. The currently existing bud sites will have already grown out, turning into thicker ones, while newer bud sites will also start to appear surrounding the main cola. Because of this, the smell will also increase intensely, and it is time for you to establish a good system for ventilation, especially if you are growing indoors, in order to combat strong odors. All of these signs show that your plants are now nearing their flowering, as the pistils are now turning to amber from white. Also, the trichomes will start to turn to an opaque color, which also indicates that it is now time for you to start flushing your plant in order to get rid of chemicals before the harvest time.

WEEK 6 to 8

Since all of the strains come with various flowering times, it is quite difficult to say when the right time for your plants would be ready. However, an average cannabis plant will all be ready during these last three weeks of the flowering phase. At the same time, you will also notice that there is a very strong odor that comes from your plant. At this point, it is very important to ensure to mask this in order to avoid unwanted attention from nosy individuals. In order to check whether or not your plant is now ready for harvest, you can start checking the THC glands in order to see if they have already changed from clear to an opaque color. If most of the THC glands have turned opaque, this is a good indication that the plant is now ready for harvest. Trichomes turning into amber are also another clear indication that your plant is now ready for harvesting, cutting, drying, and curing for your use later on.

Bottom Line

About a month after the start of the flowering stage, you will start to notice more and more changes happening. This will serve as a signal that your plants are starting to mature. The buds will distend and expand, which is just normal. Once your plants have grown, you can now start to adjust everything else, including the nutrients, temperature, humidity, and other factors per the need of your plants during this phase.

The length of flowering time may differ by each strain so it is very important that you know the background of the strain that you are growing.

For a complete growing guide, check the Growing Elite Marijuana eBook.

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