The vegetative period is the main growing phase for your cannabis plants. It is where they try to reach their full growth potential and bulge out into a full-bodied, beautiful cannabis plant. At the beginning of this phase your cannabis plants should be roughly 3-4 nodes high, with stems 4-6mm thick.
In nature, the vegetative period takes place in summer, when wild cannabis has long, sunny days to take full advantage of the sun. This causes the plants to shoot up, producing an abundance of new branches and leaves. The cannabis plants will also bulk up the thickness of their stems and branches to help support more weight as it grows. As the summer comes to an end, and the days get shorter it will trigger the next stage within the cannabis plant, the flowering stage.
The advantage of growing indoors is that you have full control of the light cycles, meaning you can transition your marijuana from the vegetative stage to the flowering stage when ever you want, keeping it in a vegetative state for as long as you need - you can use an 18/6 photoperiod whilst your cannabis plants grow, and when you are happy with the size of them you can switch to a 12/12 photoperiod to simulate the change of the seasons. This will trigger flowering within the plants. Most cultivators allow their cannabis to grow in the vegetative stage for 1 up to 4 weeks before forcing the change.
Occasionally you may find a cultivator who goes straight onto a 12/12 photoperiod from the seedling stage, forcing the plants straight into bloom. There can be an advantage to this if you know what you are doing. It forces your cannabis plants to remain small, allowing a cultivator to fit many more plants into their grow room. A higher amount of smaller plants can yield a greater amount of bud then a fewer amount of larger plants.
Most cultivators will subject their cannabis to an 18/6 photoperiod using a HID light. Always make sure that the amount of light hours remains consistent. Inconsistent photoperiods can cause a lot of stress in a growing cannabis plant as it will not understand what is going on – possibly stressing it to the point where it goes into self preservation mode, becoming a hermaphrodite.
In terms of color-band, a bulb on the blue spectrum will be best to encourage strong stem and leaf growth (see our article on color bands).
Nutrients are an important part of your cannabis grow, they provide your plants with essential components they need to perform their bodily functions. Within this stage your plants are going to need a lot of nitrogen; it is pretty much involved in every aspect of growth.