vegetative phase / growth phase in cannabis

The first two leaves that appear are the cotyledons. The stem grows upwards and after a few days the first two real cannabis leaves appear. The little plant is now considered a seedling.

The growth phase for cannabis grown indoors usually lasts 3-6 weeks. During this time, a branched root system is formed. The growth still progresses hesitantly to moderately. Water and temperature are extremely important in this phase of life. Young roots are still small and although they do not yet have such a high water requirement, this must be constantly available, as well as warmth, otherwise they will dry out quickly. Too much water, however, is also detrimental, drowns the little plants and can result in fall sickness or root rot.

Seedlings need 18 hours of light every day. In the first two weeks of life, even less light is sufficient and fluorescent tubes or energy-saving lamps (150W, 200W, 250W) can be used at a small distance from the plants. Later on, the cannabis plants need more light to develop properly.

As soon as rapid leaf formation begins, the seedling phase is over. The cannabis plant is now visibly growing and gaining mass. The vegetative phase or also called the growing phase begins. The cannabis plants are usually repotted at this point because they need a larger environment.

Once the marijuana plant has developed a branched and strong root system, it begins to develop leaves quickly and rapidly. The production of chlorophyll in the leaves increases and the plants produce as many new leaves and branches as the environmental conditions (light, water, nutrients, climate) allow. If everything is right, some varieties can grow up to 6 cm per day.

If the plant is not properly cared for at this point, or if mistakes are made with watering, it can take a few weeks to recover. A healthy vegetative phase with an optimal environment is the key to thick, potent buds and big harvests.

Cannabis plants must be able to develop unhindered in the growing phase. During this phase, they are illuminated with a sodium vapour lamp for 18 hours a day. If cannabis plants receive 18 hours of light, they will stay in the growing phase for over a year and theoretically much longer.

During the growth phase, water and nutrient requirements change or increase. Cannabis plants need more nitrogen, phosphorus, potassium, magnesium, trace elements and sulphur during this time. The larger the plant and its root system, the more water is consumed accordingly.

In the course of the growth phase, strong side branches are formed on which the flowers later grow. With photoperiodic plants (i.e. non-automatic varieties), the daily exposure time can be used to control when the plant should enter the flowering phase. Flowering starts some time after the daily exposure time has been changed from 18 hours to only 12 hours.

Pre-flowering starts at the end of the growing season. Regular cannabis plants show their gender in advance and males can be sorted out early. Only female cannabis plants produce the potent and desired buds. You check daily where the side branches meet the main stem. You can read more about how the sex determination of cannabis works here.

During the growing phase, various plant training methods and cultivation techniques are used that can help to increase yields, keep plants healthy and grow the most potent grass possible. You will find much more about this in our other articles:

• Prune cannabis plants
• Fimming
• Lollipopping
• How do you top a cannabis plant and take a head cutting from it?
• ScrOG (Screen of Green)
• Maximise yields with SCROG cultivation