The flowering phase
The plant is fully grown and the end is nearly in sight. Now we are approaching the flowering phase, after which you can start harvesting. The first three weeks of the flowering phase are in fact more a growth phase. After the flowering phase of the plants has been initiated by setting the lighting to a schedule of 12 hours light and 12 hours darkness, they will start flowering (growing) explosively. They can easily double or even triple in size. I remember the first time I ever grew a plant as if it was yesterday. I was amazed to see that the little plant quickly transformed into a giant. The buds keep swelling, the crystals start being formed and the specific odour of the plant continues to develop, which makes it hard to wait until the buds can be harvested and you can enjoy the first joint of your own harvest.
Grow and bloom fertiliser
During the flowering phase you have to switch to a bloom fertiliser. Some growers keep giving their plants grow fertiliser in the first and sometimes in the second week of the flowering phase, because it is a kind of transition period and the plants still need building blocks to grow quickly. This will make the plants grow a bit taller. It all depends on what you want. By managing your use of fertilisesr, you can control the size of your plant. If your plants already have the right size and you want to keep them smaller (because for instance space is limited), immediately start giving them bloom fertiliser. If your plants are still a bit small and the space is not used optimally, you can continue administering grow fertiliser. They will grow a bit taller. The differences are not extreme, but a couple of centimetres can make quite a difference.
After a blooming period of three weeks, the plants have achieved their maximum size. They will no longer grow in height and width but will start forming buds. It is really important to administer blooming fertiliser then, because the plants need more phosphorus and potassium. These are important building blocks for a good bud formation. PK 13/14 is a mixture high in phosphorus/potassium that stimulates flowering and fruiting. It is usually indicated on the bottle how much you have to administer. Make sure you do not give the plants too much, otherwise you risk overfertilising them. Suzy’s Tip: Watch your plant closely and try to tell what it needs. Every plant blooms in its own way, so in some strains, the buds will grow from the beginning, while in other strains they will only grow in size and weight in a later stage. The needs of the plant can also change after a couple of weeks.
If you fertilise well, you actually don't need foliar feeding. Unfortunately, it is very hard to fertilise well. Even if you think that you are giving the right nutrients, the plants may lack something. If so, you can administer foliar feeding to your plant. The nutrients are rapidly absorbed in this way and any nutritional deficiencies are corrected quickly. The chance of overfertilising is minimal when administering foliar feeding. When growing inside, the best moment to administer foliar feeding to your plants is half an hour before the lamps go on. The light of the lamps is very powerful from the beginning, so you run the risk of burning the leaves if they are still too wet. Plants outdoors are best being administered foliar feeding early in the day, before the sun is too strong. It's no use giving them feeding when there is no light, because then the plants don't grow and they don't need extra feeding. Besides that, you increase risk of mould if they are too wet. Foliar feeding has to be sprayed on top of the leaves, once or twice per week. When giving foliar feeding, you also have to watch your plant closely to discover which nutrients it needs.
If space is limited, you might want to top or bind down your cannabis plants. Topping is removing the top of the plant. You will get two main tops instead of one. These do not grow as tall as one top but they yield more. You can bind a plant down by pulling the biggest bud down and binding it with slight tension. This will give you the same effect as topping, but you have the advantage that the largest bud is retained. The lower branches will develop better and the plant will grow bigger buds.
For a good flowering period the plants need sufficient CO2 (carbon dioxide). They need this to grow powerfully during the hours that there is light. The more CO2 is present in the air, the faster the plants will be able to develop and the better they will be able to withstand high temperatures. You can use fans, but in good growing spaces, holes are made in the ground at one side to let air in, while at the other side an extraction system is installed as high as possible. This ensures an optimal circulation of air, from which the plants benefit by using the CO2-rich air that is continually circulating. Fresh air is continually sucked in through the holes in the ground. A fan is also very important. These do not only ensure good air circulation, but also give the plants a pleasant breeze which will cause them to grow even better.
The period in which the buds of your cannabis plant start growing quickly is the most important in the flowering period. Depending on the strain, that's usually after about 3 to 5 weeks. You can continue spraying your plant until then, because the buds have not yet become hard and compact, but you shouldn't after that. So you can opt for preventatively spraying your plant. When the buds start growing rapidly, you can't do much more than administering nutrients and enjoying the wonderful sight of the buds that are gradually being formed. More and more white hairs will grow and the separate little buds will steadily grow inwards to form one big bud.