The vegetative stage is extremely important when growing cannabis plants. It is the stage before flowering, where plants will grow leaves, growth tips , stems and branches. In this article, we explain to new growers what the vegetative stage is and how to control it. Also, what nutrients for the vegetative stage a cannabis plant needs, how to grow the best plants and clones during the veg cycle, and more!

Young cannabis plant transplanted and ready to hit the vegetative phase.

Understanding the vegetative growth stage and cannabis plants

Regardless of whether you grow weed from seeds, clones or autoflowering strains, the plants will need to go through a vegetative phase before flowering. The easiest way to think about it is to break down the lifecycle of a cannabis plant into five different stages.


The seed germination stage will be the moment you germinate the seeds in water, moist paper towels or directly into the soil or alternative growing medium such as coco coir or rockwool. The seedling stage will last around 14 days and is the point when your cannabis seeds are now 10–15 cm tall. The vegetative period then starts once the seedlings have become big enough to grow a healthy mass of roots and the first few sets of leaves and are able to stand up and support themselves.

● Seed germination stage
● Seedling stage
● Vegetative stage
● Flowering stage
● Harvest stage

Controlling the veg phase with grow lights

There are plants that flower depending on the light.
There are three types of plants according to their light requirements – photoperiod – for flowering.

Short-day plants flower when the day length is below a certain threshold.
Long-day plants flower when the day length is above a certain threshold.
Day-neutral plants for which light is not the determining or triggering factor for flowering.


Although they are called short, long or neutral day, it is known that, in reality, plants measure the hours of continuous darkness rather than the hours of light as you can see in the graphic.

Graphic explaining how the flowering of a short-day plant works.

When growing indoors, we can manipulate the hours of light to trigger plants to flower or not.


For example, cannabis is a short-day plant, it will flower when the plant detects at least 12 hours of darkness.
So, to keep your weed plants in a vegetative stage you will need to set your timer to 18 hours of light and 6 hours of darkness. This should be the case if working with cannabis seeds, clones or mother plants. The reason why your grow lights should be on for long periods of 18 hours a day is to mimic the long days of Spring and Summer. It is only later in the year, from August onwards, when plants will prepare for the flowering stage once the light period reduces to 12 hours per day.


What nutrients does a plant need when growing? There are specific nutrients for the vegetative phase?

If you are new to growing cannabis and assume that the soil you are using has everything the plant needs, then you are right. Of course, there are many ways to provide nutrients for weed plants, with soil being the most simple and practical one.


There are three primary nutrients, which are Nitrogen, Phosphorus and Potassium. Then, the secondary nutrients a cannabis plant needs are Calcium and Magnesium. Trace elements are then required in tiny trace amounts, however, there should be an overall balance of all the nutrients mentioned during the entire lifecycle of a cannabis plant’s life.

Detailed shot of the NPK values in the Growth-C label.

Nutrient control and the development of roots

How healthy your plant’s roots are during the vegetative growth stage will play a major role in the uptake of nutrients, ability to photosynthesize, the health and vigor of the leaves, and the development of the plant canopy’s shape and structure. If you really want to give your cannabis plants the best start in life, then we recommend using Rootbastic, ATA Rootfast, ATA NRG Root – C and B’Cuzz Root Stimulator.

3 ways to ensure the best growth during the vegetative phase

If your goal is to produce large-yielding weed crops, then you will want to get your plants as big and bushy as possible during the vegetative period. Below are 3 top tips to consider, helping you grow the best plants possible.


1. Plenty of air for the roots

Big roots mean big fruits, so take the time to make sure your growing medium can retain high amounts of water as well as air pockets. The more oxygen and warm air present, the greater the root mass will become, and the easiest way to do this is using a 40–50% ratio of perlite to soil or coco, depending on your preference. Avoid dense growing mediums that become heavy when fully saturated. Peat or coco light mixtures are perfect for this purpose. They improve oxygen levels, allowing the promotion of root mass without restricting growth.


2. Give your plants the nutrients they need.

If you grow in pots, the nutrients in the small portion of soil that supports your plant will eventually run out. In that case, you will need to add nutrients to your plants on a regular basis. This can be by using slow-release solid fertilisers, such as Upgrade, or by using fast acting liquid fertilisers such as B’cuzz Growth or B’cuzz Soil A&B. Also, as your plants grow, you will need to increase the pot size, which tends to stress them and slow down their growth. To help your plants cope better with stress, so that it doesn’t affect their growth and production as much, there are solutions like B’cuzz Booster Uni that provide them with micronutrients and plant extracts that relieve stress and improve the plant’s photosynthetic capacity.

3. Foliar feeding

Basically spraying the tops and undersides of your cannabis plants with a mild nutrient solution. ATA NRG Alga -C will provide the plants with an organic-mineral solution, ensuring the leaves and stems grow with a healthy vibrancy and waxy shine. We recommend always making a mild solution when foliar feeding weed plants and stopping spraying your plants once you enter the third week of the flowering stage.


4. Temperature and high humidity levels.

There are certain parameters that should be met during the vegetative stage and growing indoors, and one of those is high humidity levels. When growing plants indoors with temperatures close to 24 degrees Celsius, the humidity should be around 75–80% for optimal plant growth. Remember, cannabis loves warm and wet conditions, especially during the seedling and vegetative periods.



The vegetative stage is where a cannabis plant will focus on the growth of roots, leaves, stems, and growth tips. How productive your weed plants will become will also depend on how well they have grown during the vegetative period. The correct balance of plant nutrients is also a fundamental part of growing top-of-the-line cannabis buds. Foliar feeding is an excellent and inexpensive method of providing plants with a wide range of primary, secondary and trace elements. Growers should be aware that the vegetative stage is supposed to replicate the great outdoors, so remember that warm and humid is the sweet spot.



Atami always recommends checking your country’s laws regarding the cultivation of plants such as cannabis. We do not enable or encourage the cultivation of such plants outside the legal framework of each country.

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