How To Grow Weed During The Vegetative Stage

Image of cannabis plant in the vegetative stage

The growth of a cannabis plant goes through multiple stages. From germinating your seeds to finally harvesting your crop, understanding how to look after a cannabis plant is imperative to ensure you get maximum results.


Once your seeds have germinated and been transferred into your growing medium of choice, it’s time to give some much-needed light and water to your young seedlings. Even though the seedling stage is not considered a part of the vegetative stage, the vegetative stage begins when the seedling starts growing the first true leaves.


Here we will go through exactly how to grow weed during the vegetative stage. From what the vegetative stage is, to how you can get the best out of your plant.


What is the vegetative stage?

In simple terms, the vegetative phase is a period of the growing cycle that takes place after germination and before flowering. During this stage the plant will develop its structural integrity, meaning the stem and leaves take form while the roots grow. Explosive growth occurs during the vegetative stage, the stem will thicken and gain a lot of height and the space between nodes will increase dramatically.


Overall the main objective of the vegetative stage is for the plant to grow as big as it can before it transitions into the flowering stage.


How long does the vegetative stage last?

The length of the vegetative stage is a matter of personal preference. It can be from 4 weeks to as long as 12 depending on the cultivar and the goals of the grower. We would recommend around 6-8 weeks as the optimal time to let your plant stay in the vegetative stage.


However, there will also be factors to consider when deciding to flip the switch and transition your plant into the flowering stage. Depending on your grow space you may need to shorten its vegging stage, due to it outgrowing the area it’s grown in.


These principles obviously only apply to those growing indoors, where they have full control over the conditions their plants are grown in. For those cultivating marijuana outdoors, the environmental control is all down to nature. Outdoor-grown plants will stay in the vegetative stage until the season changes from summer to autumn.


Light cycles to use in the vegetative stage

During the vegetative stage, your plants will require the most light during the whole growing process. It is widely recommended to use an 18/6 light cycle. Whilst some growers may choose to keep the lights on for 24hrs a day, it’s kinder to your plants to give them some rest, keeping them nice and healthy, it will also reduce your electricity costs.


The early leaves will begin to photosynthesize, absorbing the light and furthering the plant’s growth. Always remember to keep your lights fairly close to your plants but not so close that the leaves will burn.


Caring for your plants during the vegetative stage


Lighting is one of the most important factors when growing cannabis. Therefore growers must start with a good set of lights. LED lights are recommended due to their low operational costs and low heat emission. However, HIDs are also commonly used.



No plant can thrive without water. It is essential to the growth and health of cannabis plants, transporting nutrients up the stem and leaves to where they are needed. Giving your weed plants adequate water is key, overwatering or underwatering can have serious, negative effects on the growth of your plant. So make sure you only water when needed, a good rule of thumb is to wait for the top 2-3cm of soil to dry out before watering again.



During the vegetative stage is where you begin to feed additional nutrients to your cannabis plants. Plants require higher levels of nitrogen in the vegetative stage, which contributes to the growth of stems and leaves. They also require additional levels of potassium and magnesium, to aid photosynthesis and growth. Specific nutrient mixes are available for the vegetative stage, however, you need to gradually introduce the amounts you feed your plant, as too many additional nutrients can lead to nutrient burn and other health issues.



Cannabis plants in the vegetative stage thrive in temperatures between 20-30°C. Keep a close eye on the temperature in your growing space using a thermometer. If the temperature drops too low then it can have negative effects on your plant. If you live in a particularly cold climate you can use a heater to help increase the temperatures.



Airflow is another aspect that is vital to keep vegging plants in good health. Having a fan in your grow area will help air circulation and also strengthens your plant.

In a grow tent, input and extractor fans will help keep the air fresh. They’ll bring in CO₂ and remove excess oxygen. Having good airflow will also help to prevent mold from occurring.


How to help increase yields?


During the vegetative stage is when you can begin training your plant. Training allows you to shape and manipulate the structure of your cannabis plant to allow more light penetration into the whole plant. This can help dramatically increase the yield of your plant. Training such as LST (Low-stress training) also helps when you need to keep the height of your plant under control. By bending and tying down branches and stems, you can mold the plant into the shape you want it to grow.



Topping is another form of cannabis plant training that can help achieve overall higher yields. It is an HST (High-stress training) technique, which is the process of cutting off the growing tip of the main stem of a cannabis plant. Topping is performed in the vegetative stage when your plant has developed between 3-5 nodes. It is essential to time this training correctly, as it can seriously stress the plant if undertaken too early or too late in its growth.


What issues to look out for?

Sexing your plants

If you are growing regular seeds that are capable of producing both male and female plants, then you must pay attention to the sexing of your plants. If you are only aiming to grow marijuana plants that produce resinous buds, then you will need to make sure you remove any male plants from your growing space. The plants will begin to show signs of their sex after 4 weeks, so if you discover males amongst them you must remove them as soon as possible.



During the vegetative stage is when marijuana plants have drastic growth in height. Although it will please you to see your plant increase in height, it is also worth keeping an eye on whether it is stretching too much. You want your plant to be tall and bushy, however, if your cannabis plant is growing tall with a lot of spaces in between branches, it is possible that the light source is not strong enough. If this is the case then it is recommended that you upgrade the lights to ones with a higher lumen count or add another light source.


Yellowing leaves

If you notice the yellowing of leaves at any stage of your cannabis plant’s growth before it is ready to be harvested, then it is a sign that something is not right. It could be caused by nutrient deficiencies, underwatering or light burn. If you notice some leaves are yellowing then it needs investigating immediately.


Ensuring your cannabis plants remain healthy and have strong growth during the vegetative stage will give you the best platform to produce high yields of beautiful buds. Paying attention to the needs of your plant is vital to achieving this, and although everything we have mentioned in this article is important during the vegetative stage, remember growing weed is all about experience and will become second nature after a while.


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