Growing Cannabis: the Vegetative Phase

You have successfully germinated your seeds and are now seeing new leaves developing on your plant. You officially entered the vegetative, or commonly called “growth” phase. In this article, we’ll give you some general guidance and tips to ensure your plants develop well before the blooming phase.

The vegetative phase is when the plant experiences long periods of light during the day. That corresponds to Spring and early Summer outdoor, or to 18 hours of light per day when growing indoor.

A good start is key

During the early days of their lives, seedlings are quite fragile. From now own, you should put your plant in good conditions so she can grow consistently and reach an optimal size that will maximize your yield.

During the growth (vegetative) phase, the lamp timer will be set on 18/6 (18 hours of light / 6 hours of darkness). The plant will develop in breadth and height.

Your plant will develop branches that will support the buds, but also leaves that will allow photosynthesis to happen and therefore the plant to grow exponentially. In other words, as the plant develop leaves, it captures more light, which makes the plant grow faster and faster.

The plant will need to be fed in nutrients. The roots also need oxygen, while the leaves will need CO2 during daytime. It will be important to control your environment in order to ensure a good growth.

Soil and mediums

The soil or medium you use will impact the growing speed. Whether you grow in soil, coco or in hydroponic or aeroponic setup, will have an impact on the nutrients you will use and the speed of growth. Soil for instance needs to remain aerated so that oxygen reaches the roots. When roots develop rapidly, they capture more nutrients and therefore support the growth of branches, leaves and eventually, buds.

Coco being lighter, it usually offers better oxygenation but doesn’t have any nutrient and less capacity to retain them. You will therefore need to be more rigorous and consistent than with soil when feeding your plants.

Growing in hydroponic or aeroponic setups usually provides the fastest growth as long as you remain precise and consistent with your nutrients dosage. Such setups offer less inertia than soil or coco when it comes to nutrients retention and distribution. You therefore have to be really attentive and proactive.

Don’t forget the roots

Root-stimulating compounds are commonly used to support consistent root expansion. Developed roots ensure the continuous development of the plant above the surface until harvest. Well-developed roots will allow the plant to capture all the nutrients you pour into the medium. During the early days, you can feed the plant(s) with root-stimulator mixed in water.

Vegetation matters

Vegetation (or growth) determines the eventual yield of your plant(s). It’s important to anticipate as much as possible the phenotypes that will manifest from your genetics. Some strains will tend to stretch between nodes, others will remain short and bushy. This, in conjunction with your growing environment will require you to train your plant(s) accordingly to maximize the yield. Large plants will require more space. Bushy phenotypes will allow you to fit in more plants into the same space.

Note that the duration of the vegetative phase will depend not only on the growth speed, the size of the phenotype, but also on whether you start from seeds or clones. Clones come from mature plants and will therefore grow faster. Seeds will take more time to be ready to be moved into flowering.

Always remember that your plants will keep stretching in size 3 weeks into the flowering phase. It is therefore important to keep this in mind if you are limited in height within your growing environment. The ideal size is when you’ve grown enough robust branches to support the production of heavy buds, but while allowing enough light to reach the lower branches.

Feeding your plants

In vegetative phase, plants will need nitrogen, potassium and phosphorus (not too much). You will therefore need to use adequate soil and nutrients to ensure a consistent supply of these minerals.

A wide range of nutrients is available on the market, and some growers even produce their own mixes. In all cases, it is critical not to over-fertilize your plants. Start low and increase dosage gradually. Keep observing how your plants react (colors of leaves and stems) as you increase nutrients concentration.

As your plant grow, their needs in nutrients will too. You should keep adjusting progressively. If the leaves turn light or yellow, this may be the sign of a lack of minerals.

Training your plants

During the vegetative phase, you’ll want to shape your plants so they capture the maximum amount of light available during flowering.

If you want to maximize your yield with a dense canopy, you may use several of these training techniques.

Topping plants

With a sharp blade, you can cut the main stem of the plant just above the third or fourth node. This will help your plant to expand horizontally. This may also cause the growth to slow down for a week but growth will catch up in a Y-shape.

Hemp defoliation

Defoliation consists in removing leaves in the vegetative phase. This will slow down growth but also enable a better control over the shape and growth speed of the plant. This technique is used to give more light exposure to buds.

Low stress training

Low stress training consists in bending or tying down your plants. The goal is to foster a more horizontal growth and spread out canopy. You can bend the main stem as well as branches. You should ideally tie down the tallest branches. SCROG is a popular low stress training technique.

High stress training

High stress training (also called “super cropping”) is usually done just before entering the flowering phase. It consists in snapping the bud-bearing branches and expose the bud-producing zone horizontally under the light. This technique is for experienced growers.

Soon enough, you’ll be able to reduce the light time to 12 hours a day and officially enter flowering phase.