There is a lot to be said about mature cannabis plants in the middle of flowering. From male and female plants, nutrient deficiencies and the risk of mold to the perfect growing conditions in the grow box, with the knowledge of Cannabis in bloom fill entire books. We want to try to do justice to this big topic with a blog post. And of course, the best thing to do is to start from the very beginning.
When do I send my cannabis plant into flowering?
Anyone who grows photoperiod varieties indoors is always faced with the question: When do I initiate flowering? In nature, cannabis (if it is not an automatic) initiates the flowering phase following the growth phase by means of the shortened light cycle towards the end of summer. The decreasing number of hours of sunshine lets the plant know that autumn is not far away and the plant reacts - cannabis is an annual and the plant dies after flowering. However, anyone who grows indoors has to shorten the light cycle themselves. While the growth phase should bring at least 18 hours of light, in order to send cannabis into flowering, this period must be shortened to 12 hours. As a rule, a timer for the lighting was already installed when the grow box was assembled, which can now be adjusted accordingly. But to the actual question: When is the perfect time to initiate flowering in my cannabis ladies? In fact, you have complete freedom here. You should give the plant a minimum of 4 weeks after germination so that it has the opportunity to become strong enough. In principle, however, there are no restrictions here. If you want, you can leave a cannabis plant in the growth phase for years. This is exactly how it is done with mother plants. Mother plants are cannabis plants whose sole purpose is to produce cuttings. These cuttings then become healthy young plants in just a few days - this process of propagation (compared to growing from seed each time) has some advantages, which we will not go into in this article.
The right time – these questions are important
To help you decide on the right time for your home grow project, we have summarized a few factors that will help you:
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How big is your grow box? Your plant should have reached a maximum of half of its available growth height before you send it into flowering. Cannabis likes to stretch at the beginning of the flowering phase and can then continue to grow steadily throughout the entire flowering phase. With sativa plants in particular, you should expect the size to double during flowering. |
How much yield do you want? If you want to get the most out of your ladies, you should give them as much time as possible in the growth phase. Because: smaller plants mean less weed. If you only need a handful for "now and then", you will save time and energy if you start the plant to flower early. |
How many plants do you have? If you have more than one plant in your box, the size that the plants can reach changes accordingly. If you have a 1 m² box, for example, you can fit one large plant or two to three smaller plants. The more plants you put in the same space, the smaller they will be. Your advantage: With more than one plant, you can shorten the growth phase accordingly without losing yield. Here's a reminder of the CanG: In Germany, you are allowed to have a maximum of three flowering plants at home. |
Are you growing your cannabis outdoors? Then you obviously have little influence on the start of the flowering phase. You can see the first signs of flowering activity in your outdoor cannabis plants within the first few weeks after the summer solstice (the longest day of the year).
How do I know if cannabis is flowering?
Initiating the flowering phase of cannabis can be exciting, especially with the first few grows. Watching for the first signs, waiting excitedly to see how the plant will change and, above all, the harvest is not too far away. There are a few small clues to help you recognize cannabis in flower. However, this mainly applies to the first few days or one to two weeks, because from then on the plant shows increasingly clear signs of flowering. Cannabis is not one of those plants that flower without a sound: they develop the typical, sometimes very penetrating, weed smell. If you can't wait and are looking for clues every day, then the first thing to look for is...
… the pistils: Cannabis begins to develop pistils as soon as it starts flowering. Look at the nodes on both the main stem and the side branches. Soon after flowering begins, you will notice small white threads about 0,5-1 cm long. These are the pistils, which will turn orange towards the end of the flowering phase.
… dem odor: If you have a keen nose, you can already detect the first changes in the smell of the plant.
… dem Stretch: Have you noticed an unusual growth spurt in the last few days? This is a good sign. This is the stretching that we mentioned earlier in the early flowering phase of cannabis. The plant is growing even more in order to tower over surrounding plants and thus gain better access to the last hours of summer sunshine.
My cannabis is flowering – what should I expect now?
So you have successfully determined that your cannabis plant is beginning to flower. During the flowering phase, your lady now has different requirements for her environment. You must make adjustments in terms of temperature, humidity and light intensity. And very important: correct fertilization. Especially towards the beginning of the phase, cannabis in the flowering phase has an increased need for nutrients, especially nitrogen. Nitrogen deficiency is therefore also one of the most commonly observed reasons for yellow leaves in the flowering phase of cannabis. Therefore, observe your plant carefully and note down if you notice any changes to the leaves. Is the color changing? Are they getting darker, lighter, yellowish? Are there brown spots anywhere? Is the color of the leaf veins changing? Are the leaves discolored over a large area, is the color moving from the outside to the inside, is it spotty, or only on old or new leaves? These can be signs of nutrient deficiencies.
Nutrient deficiencies
Each deficiency brings its own set of symptoms and sometimes it can be difficult to draw the right conclusions. However, the most common problems with cannabis in flowering include under- or over-watering, CalMag (calcium and magnesium) problems and a deficiency or excess of one or more of the three main nutrients: nitrogen (N), phosphorus (P) and potassium (K).
Pro tip: If you are sure that you are giving your plant enough of the right nutrients, but it is showing signs of deficiency, then check the pH value of the water you are watering. Whether it is flowering or not, cannabis can only absorb nutrients within a limited acid-base balance. If the pH value is between 5,5 and 7, everything is fine. Below or above this, the nutrients are not reaching your plant.
odor
If you haven't taken care of it yet, do it now: an activated carbon filter in your ventilation system. Cannabis in flower develops magnificent scents that range from sour or spicy to sweet and even diesel aromas. CanG states that you can only grow your plants if you can do so without disturbing your neighbors. So, it's better to take care of it sooner rather than later! Once the stairwell is filled with the wonderful aromas of terpenes, it's hard to get rid of them.
Temperature & Co.
As the flowering phase progresses, cannabis prefers it a little cooler. Ideal temperatures range from 26 degrees during the day to 16 degrees Celsius at night - and gradually drop to 24 degrees during the day. The same applies to humidity. While the plant can tolerate higher percentages during the growth phase, the RH (relative humidity) should be reduced to 40% (towards the end of flowering). Depending on your setup, this may not be possible for you, but do your best to keep it from being too high. The reason: mold development. Due to their structure, cannabis flowers are susceptible to mold - and once moldy, it must be removed immediately. This is annoying because it naturally reduces the overall yield. If we are talking about light intensity, however, this should be increased. Cannabis in flowering needs several times more light than what the plant needs for good development in the growth phase. So if you have been using dimmed lamps or even weak LEDs, now is the time to replace them. However, when it comes to the light requirements of cannabis during flowering, you can make sure you have the right specifications when buying your lamp. It's best not to go for the cheapest product right from the start, but check:
- How much power does the lamp have? You can get by very well with 600W HPS lamps - so if you want an LED, look for the note "equivalent to 600W HPS". Anything significantly lower is too weak (especially with LEDs).
- How high is the light intensity? This is shown in PPFD (indicated in the unit µmol/m²s). There is usually a diagram in the product description that shows you the light intensity depending on the distance between the lamp and the plant. When flowering, cannabis needs at least 800-900 µmol/m²s.
- How energy efficient is the lamp? During the growth phase, the lamp runs for 18 hours, and during the flowering phase it runs for another 12 hours - and this for months. The power consumption of a grow box should be considered and there are now valuable energy-saving options, especially for lamps.
I discovered mold in my cannabis flowers: what can I do?
If you find mold, get rid of it. Consuming mold - whether smoking, eating or something similar - is never a good idea. There are two times during your grow when you should keep an eye on your cannabis flowers like a fox: towards the end of the flowering phase and during the curing phase. Outdoor plants in particular are at an increased risk of mold during the flowering phase, especially when it starts to rain a lot in the fall. But even with indoor plants, you have to make sure there is sufficient air circulation in the grow tent, because their compact, dense growth means that cannabis flowers are not as robust against spores. If the humidity in the room is not high, you will have few problems during the drying process. But as soon as it's time to cure your flowers, you should keep an eye on your nuggets again. To cure, fill your dried grass into jars and make sure that the humidity in the jar is between 60 and 65%. Open the jar twice a day for a few minutes to allow air to circulate. You should also check the flowers for signs of mold each time.
Mold in the flowering phaseIf your plants have not yet been harvested and are still in the flowering phase, you must remove the affected flowers. In living plants, the appearance of mold is also called "bud rot" because the flowers rot from the inside out. If the mold has then visibly reached the outside of the bud, the entire flower usually has to be cut away. You will usually find that the inside of the flower has turned brown, i.e. has completely rotted through, and turns to dust as soon as you start to work on it. Be generous when cutting, the mold spores may have already spread to surrounding tissue, even if they are invisible. Mold during curingIf you discover mold when checking your flowers during the curing phase, these buds must also be sorted out immediately. And even if it hurts: throw them away. Smoking is harmful enough to your health without the material being moldy. |
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Plant training for cannabis in flower
Plant training involves various methods of intervening in the natural growth of the cannabis plant. The goal: to increase the yield. There are many different training techniques from LST (low-stress training) to HST (high-stress training). Some start in the growth phase, others only become really important in the flowering phase. This includes defoliation - also called defoliation. As the name suggests, defoliation is the removal of leaves from cannabis flowers. It does this for two simple reasons: to allow more air and light to reach the flowers. This reduces the risk of mold and helps your plant focus its energy on what is important to you - the delicious flowers. If the plant has fewer leaves to tend to, it can invest that energy in producing stronger flowers. The danger with defoliation, however, is that you remove too many leaves. Since the plant needs its leaves for photosynthesis, excessive defoliation limits the plant's energy production instead of promoting its growth.
If you have already started with training techniques such as Mainlining and ScroG in the growth phase, you can now start with lollipops continue. Similar to defoliation, plant material is cut away here, but not from every branch around the flowers, but from the entire lower half. Ideally, you have stretched a ScroG net, then you can remove everything below the net. Even small, weak shoots that have not managed to stretch their heads over the net. In the end, the plant resembles a lollipop with a bare stem, hence the name lollipopping.
To be avoided with cannabis in flower
In addition to all the helpful tips that should be observed when growing cannabis during the flowering phase, you should also take a moment to think about what is best to protect the plant from. And that is: too much stress. Training techniques are helpful to a certain extent, but if the plant experiences too much stress, it can start to hermaphrodite.
Hermaphrodite flowers are when the plant suddenly has male sexual characteristics as well as female ones. Why is that not good? Because male flowers form pollen sacs. The pollen then pollinates the flowers of your other plants and instead of producing high THC levels, they produce seeds. The flowers can still be smoked, but they are significantly weaker. The same applies to the hermaphrodite plant. If the flower has male flowering characteristics, it will produce less THC. You can let it continue to grow, but you shouldn't get too excited about your harvest. And very important: If you have more than one plant, you have to keep it separate from now on so that it can't pollinate your other ladies.
Repotting is particularly stressful for the plant. Think of it like moving house - you'll need a few days of rest afterwards. So it's best to avoid repotting cannabis while it's flowering altogether, as it will only prolong your flowering phase and possibly trigger hermaphrodites.
The flowering period of cannabis
The ever-seductive scent wafts out of the grow box, the flowers are already dense and heavy, and now you're wondering: When do my cannabis flowers actually need to be harvested? You can use the information for your variety as a rough guide. This always tells you the approximate duration of the flowering phase. Some varieties need up to 11 weeks to fully mature, while others show full flowers after just 7 weeks. Fortunately, there are certain characteristics that you can use as a guide.
The pistils
Towards the end of the flowering period, you will notice that the fine white hairs we described earlier turn orange or brownish. More and more of these clearly visible pistils take on a darker tint. However, with some varieties you can see this towards the beginning of the flowering period and it is by no means an exact measurement.
The trichomes
To really find out how far along your cannabis plant is in its flowering phase, you should look at the trichomes, the small resin crystals on the flowers. These can be seen with the naked eye, but you will definitely need a magnifying glass to see the state of the crystals. A pocket microscope with 40x magnification will come in handy. Depending on the ripeness of the flowers, you will be able to identify the trichomes as clear, milky or amber. The perfect harvest time is a myth, but as a rule of thumb, you want to harvest when as many of the crystals as possible are milky. In the early stages they are still clear, but as the flowering progresses they become milky. When the active ingredient starts to break down again, the trichomes turn amber. A few amber crystals (about 15%) are not bad, on the contrary: they change the effect of your weed to a slightly more body-heavy high. But if too many crystals turn amber, you lose a lot of the active ingredient – the THC content drops again.
Buy ready-made cannabis flowers
That's possible! However, with the restriction that these flowers for sale must not contain THC. Or rather: They must have a THC content of less than 0,2%. In Germany, only CBD flowers are offered for sale. Nothing has changed here even after the CanG was passed. Anyone who wants to consume flowers with THC must either grow them themselves or have a doctor's prescription issued for the use of cannabis for medical purposes. However, these prescriptions are not given to everyone and the process is long and confusing - since it has also been legal since April 2024, most users, like you, will tend to grow at home. Of course, you don't necessarily have to grow cannabis flowers with THC, you can just as easily grow your own CBD flowers instead of buying them from online shops.
By the way: Everything you need to enjoy your harvest can be found in our shop. With our vaporizers you can consume your noble home-grown cannabis gently and with less pollution than smoking. Whether a slim stilus or the classic silhouette of our Convectum: The Hizen vaporizers reliably accompany you through your vape sessions.
You are now almost a pro when it comes to flowering cannabis, but you will learn most of it once you have made your first mistakes, identified your first nutrient deficiencies or posted on forums for the first time looking for help. You will harvest some plants too early and others too late. And above all, you will quickly find out what works for you when growing and what doesn't. Although there are very specific requirements that cannabis makes of growers, it is important to remember that hemp is an incredibly robust plant - it is not called "weed" for nothing. Once you have successfully completed your grow and are letting your cannabis flowers already? Then congratulations! And don't be afraid of making mistakes. Some are annoying, some are easy to deal with - you learn from all of them.
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