The Vegetative Phase Of Cannabis

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Categories : Cannabis cultivation

The Vegetative Phase Of Cannabis

The vegetative phase sets the foundations for buds to develop. Check out these tips and tricks to ensure a successful and healthy veg.

During the vegetative phase, small cannabis seedlings develop into full-sized plants. Watching one's canna-babies grow into strong and mature specimens is a heartwarming experience. We want to raise vigorous, healthy plants so that our beloved buds can flourish. This is exactly what the vegetative phase is all about. Let’s check out the best practices to get the most out of the veg.


The vegetative phase begins when the seedling emerges from the soil and embraces the light of day. The end of this phase is marked by the beginning of the flowering phase. During the vegetative phase, cannabis plants grow in size. The stems become thicker, the number and size of leaves increases, and side branches grow out, stabilising the plants. Growers want to ensure that plants are robust and healthy before the flowering phase begins. This provides the buds with the tools they need to grow in size and quality.


Genetics play a crucial role in a plant's development during the vegetative phase. Some strains, such as autoflowering varieties, grow really short, between 30-100cm. Some sativas, on the other hand, can reach 4m in height. Indica-dominant strains will become stubbier and bushier than landrace sativas. Indoor growers won't choose the tall sativa strains because they might grow too big for the space. Selecting the right genetics for one's operation is the first, most important step.

In order to keep naturally tall genetics from stretching to the ceiling, techniques such as topping, SOG, and ScrOG can be used to influence bushier growth. However, these methods need to be anticipated in advance to give the plants enough time to adapt to the changes. It's crucial to bear in mind that cannabis plants stretch significantly during the flowering phase. Indicas usually stretch less than sativas, which can explode up to 3 times their size after the flowering phase begins.


Cannabis plants thrive in various growing media during the vegetative phase. Many growers prefer to use soil, the old-fashioned method. The roots absorb necessary nutrients from the soil, allowing plants to thrive. There are various soil mixes that can be used, which differ in quality. The two main aspects to consider before purchasing soil for cannabis plants is the water retention level and texture of the soil.

The soil needs to be able to retain enough water for the roots to receive nutrients over time. If the soil is too dense, however, the roots won't receive as much oxygen as they require and plants will become sick. The soil texture should be rich and dark, but not muddy. Many soil mixes are pre-fertilised, which is usually great for the plants. But some can be over-fertilised and cause nutrient toxicity, which is highly undesirable.


During the vegetative phase, plants require significant amounts of nitrogen. Many growers prefer to use fertilisers with a 2-1-1 NPK (nitrogen-phosphorus-potassium) ratio. The number one mistake made by novice growers is over-fertilising the plants. When the edges of leaves begin to turn brown, or the green colour on leaves is too dark, you may be dealing with nutrient toxicity. It’s rare for cannabis plants to be under-fertilised during the first stages of the vegetative phase, but if the plants look a bit weak and the green color is meek, perhaps extra nutrients should be added.

vegetation phase cannabis


During the vegetative phase, plants will start growing large fan leaves, which absorb light and turn it into energy via the process of photosynthesis. There’s an unwritten consensus among master growers that photoperiodic cannabis plants should be exposed to 18 hours of light and 6 hours of darkness during the veg for optimal results. Once the flowering phase begins, the light cycle is switched from 18-6h to 12-12h.

This switch signals to the plants that the autumn season has begun, and it's time to flower. Autoflowering varieties don’t function in the same way as photoperiod-sensitive plants. They can receive up to 22h of light during the day. Some growers have even reported solid results by exposing their autoflowering varieties to 24h of light. However, most cultivators provide their auto babies with at least two hours of dark, if not six. Indoor growers use HPS or LED lights to provide their plants with lumens. CFL lights also work, but they're mostly used in tiny operations with limited space. Many have reported great results from exposing seedlings to
CFL lights, rather than strong HPS or LED lights. Sometimes, lights can get too hot for the plants, which leads us to the next section.


When the temperatures are too low, plants stagnate in growth and can invite in various pests and diseases. When the temperatures are too hot, the growth stagnates, the leaves dry out, and the plants stretch in undesired ways. During the light cycle, indoor cannabis plants enjoy temperatures between 23-28°C. During the dark cycle, the optimal temperatures range between 20-24°C. Outdoor-grown cannabis can handle up to 35°C because the roots are deep down in the ground where it's nice and cold. HPS lights emanate a lot of heat, so it's important to install a solid exhaust system, which pulls out the hot air building up around the lamps.


The water always needs to be pH-balanced. The roots will only absorb the necessary nutrients when the pH levels meet the root's standards. The optimal levels for soil are 6-7pH. For hydro systems, 5.5-6.5pH works fine. We can't stress enough how important pH balancing is. If one waters the soil with, say, 5pH water, the plants might not absorb nitrogen at all. Then, if you fix the pH levels, the built-up nitrogen in the soil may rush into the plants and cause nitrogen toxicity. In other words, optimal pH levels are king.

During the seedling stage, the soil should be relatively humid at all times. Once the plants become slightly larger, one should only water the soil when it becomes almost dry. Don’t fall victim to the common error of overwatering. This often occurs when novice growers want to provide the plants with as much stuff as possible. Overwatered plants are very hard to treat in soil as the only real solution is to dry it out. The common signs of overwatering are drooping and bleak leaves and chlorosis. If the plants look like they’re dry and lifeless, it probably means that they are underwatered. It’s best to keep the plants slightly on the underwatered side because it's much easier to simply water the plants, rather than remove excess moisture.

There you have it, the main considerations of the vegetative phase. It's an amazing experience when our precious cannabis plants take shape and set the foundation for buds to thrive. It’s important to check up on the plants often and attend to their needs. As a rule of thumb for novice growers, giving the plants less is usually more when it comes to healthy development.