Cannabis Flowering Stage Guide

Cannabis Flowering Stage Guide

The cannabis flowering stage is the moment we've all been eagerly anticipating. For many growers, this is the most exciting phase of growing weed seeds.

It is also the time when it is easy to make mistakes, which can severely impact your yield. Let's discuss how to look after your cannabis plant during the flowering stage, and enjoy the best harvest ever.

The flowering stage

When you switch your plants from the vegetative stage to the flowering stage, the growth of your marijuana plants will ultimately slow down, although not initially. When the flowering stage begins, and as soon as buds start to develop, it is time to alter how you treat them. They will need, for example, different amounts of light and nutrients for the flowering period.

While the plants grow and thrive like crazy in the vegetative stage, your flowering plants are now more susceptible to problems. Any issue that occurs from now on can and will affect your final harvest. So it pays to know as much as possible about the needs of your plants.

The total flowering time is about eight weeks on average and features the following phases: transition, first buds, bud growth, bud maturity, and harvest.

Step 1: how to transition from vegetative to flowering?

Using the right grow lights is vital when switching your weed plants to the next phase of their life cycle. Gradually alter the light cycles until you have a 12/12 hour light / dark ratio. Here, too, indoor growing offers the ideal chance to implement an environment that best suits your (female) cannabis plants.

The advantage of growing buds indoors is that you have control of the light rather than relying on circadian rhythms. And if you can control the light cycles properly, you will enjoy a better yield.

The initial one to three weeks of the flowering cycle is more of a transition stage, and the plants will continue to grow very quickly. Depending on the variety you use, your plants can even double their size during this time.

Our tip: during the dark phase of the 12:12 cycle, make sure things are properly dark and that no light can get through! Or your plants simply won't make buds and may even become hermaphrodites.

If grown outdoors, the natural shortening of the days as we head into autumn should signal to the plants that winter is coming, and it's time to focus on making flowers.

Step 2: Wait for the first buds

Before you discover a flower, you should support your plants as much as possible in the growth phase. You will notice that your plants grow rapidly at the start of the flowering stage. This is to be expected and is known as the 'flowering stretch'.

Let your plants grow and watch them carefully; at this point, they are growing their bud sites. If you are running out of room, you could try and gently bend them by applying a technique called low-stress training (LST).

As soon as the flowers appear, you should optimize nutrients and light. Now is the time to switch to nutrients for flowering. This is your last opportunity to manipulate the canopy of the plants before budlets start to appear.

It is important to note that only a female cannabis plant can grow buds. You can ensure you have feminine plants by buying feminized seeds or our autoflower seeds, which saves time and waste, although it is possible to use the leaves of male plants for hash.

If you notice any pollen sacs, remove the male plants from the grow room immediately, as they will otherwise pollinate the female plants and cause 'seedy' buds.

In week three or four, you will see the appearance of the first genuine buds rather than just hairy pistils. The plants' growth will decelerate from now on - it is essential to take care of their well-being at this point - they will become fussier about their nutritional needs, trying to balance between nutrient deficiencies and nutrient burn.

Related article: Guide to Nutrients for Weed Plants

Some leaves are to be expected (for example, if they haven't had enough light), but if over a third of leaves turn yellow, you have a problem on your hands. The last thing you want is a serious disease, so it's also critical to monitor your nutrient levels and closely monitor your flowering cannabis plant to make sure nothing untoward is happening.

Step 3: gorgeous, beautiful cannabis buds

Finally! Dense buds spawn among your crops. White pistils will burst forth, and the buds will get larger every day. This is a moment to stop and congratulate yourself! Here are the best tips to apply during the flowering stage to get you to the prize:

Tips to make the most out of the cannabis flowering phase! 

  • Only cut off dead leaves and branches. - It may be tempting to cut large branches, but your plants now need to conserve all their strength and health. Never be tempted to pick the newly developed buds - leave them alone, however much you may want to sample them. You can bend and tie the plants down to create a flatter canopy that allows more plants exposure to light. Try and do this when the stems are young and bendy - if you leave them too long, they will become woody and liable to snap.

  • Keep an eye on temperature and humidity levels - During the flowering stage of cannabis plants, maintaining proper air conditions is vital. Ideally, keep the humidity between 40 and 50% and temperatures between 20 and 25 °C (68 and 77 °F). This promotes healthy bud growth and reduces mold risks, ensuring a quality harvest.

  • Do not change light cycles - Once you start changing light cycles during flowering, never revert and expose your plants to light in the dark phase of the cycle. You don't want to inadvertently confuse them and risk putting them back in the vegetation phase. This could have a dramatic impact on your final yield. Use a timer never to forget when to switch your lights on. It is the uninterrupted darkness that makes your plants bloom. Ensure this darkness is final - not a minute of light at night!

  • Ensure adequate ventilation - If it hasn't already happened, your plants are now likely to develop the familiar pungent marijuana smell. We recommend using a good quality airflow system - ideally, one that is carbon filtered. Your airflow system is essential at this stage, and plenty of fresh air must be able to flow into the growing area constantly. During the flowering stage, your cannabis plants need a lot of carbon dioxide to grow optimally and healthily.

  • Add nutrients - In weeks four to six of the cannabis flowering phase, the buds get bigger and fatter. As soon as the flowers appear as tiny white pistils, your plants need more phosphorus and potassium, which are vital for good bud formation. These nutrients support both flowering and fruiting.

  • Avoid overfeeding your plants - Be careful not to overfeed your plant. A sign that this is the case is the ends of the leaves looking scorched. Don't panic too much if this is the case; it is still possible to produce good weed.

  • Provide support for heavy buds - At this point, you no longer have to worry about fastening your plant into place. However, you might consider keeping your buds high and near to the light if they're becoming too heavy for your plant.

  • Trim excess leaves - Some professionals trim leaves at this point so that their plants can mainly focus on the growth of their buds. Always leave enough leaves to keep your plant healthy! The leaves are an essential part of the plant's system and, thus, the growth of the buds. At weeks six to eight, your plant has completely stopped vegetative growth and only focuses on growing buds. Several leaves might turn brown on the lower branches, which is perfectly normal. Cannabis plants are vulnerable to nutrient deficiency at this point. Pay attention to the pH levels to ensure your plants get everything they need.

  • Avoid light burns - Even if your plants love your vigorous growing lights, you must be careful not to burn them with too much heat and light. If your setup involves a grow tent, make sure it's high enough for the lights to hang at least a foot above the canopy of your plants.

  • React quickly to potential problems - Closely monitor light and heat levels. Foxtailing is quite a common problem and describes a new bud emerging from the side of a bud that has already developed, and is usually an indication of exposure to excess light or heat. Hardly any cannabis buds will be ready for harvest before week 8. You will want to monitor your plants closely at this point; treat them with gloves! Respond to all of their needs. It can also be helpful to rinse them with plain water a few days before harvest, known as flushing. Depending on the variety, the plants should be ready to harvest between the eighth and tenth week. The intensity of the smell of marijuana can be a good indicator. The plants can turn yellowish at this time, which they usually do when they finish flowering. Do not increase the nutrient content at this point. The buds should be big and plump, which can only mean one thing ...

You've done it! Have fun with your long-awaited harvest!

What have we learned?

The cannabis flowering stage is a crucial period in a plant's life cycle. After transitioning from the vegetative stage, cannabis plants require a 12/12 hour light/dark ratio. During this stage, plants experience rapid growth, developing initial buds. Proper lighting and nutrients tailored for flowering are essential.

Ensure your plants are female to produce buds, and remove any male plants to avoid seedy outcomes. Monitor humidity and temperature as buds grow, aiming for 40-50% humidity and temperatures between 20-25 °C (68-77 °F).

Adequate ventilation is critical, as is providing flowering nutrients while avoiding overfeeding. Support heavy buds, trim excess leaves, and be cautious of light burns. Address issues promptly, and by weeks eight to ten, your buds should be ready for harvest.

To learn more about harvest time, you can check out our Harvest Cannabis Guide.