Starting Off Right: Feeding Cannabis in the Vegetative Stage

By Kyle Ladenburger
Published: August 10, 2020 | Last updated: April 23, 2021 12:33:49
Key Takeaways

A key to growing huge, robust cannabis buds is paying careful attention to the plants’ growth during the vegetative phase. This stage is key to ensuring a bountiful marijuana yield.

Often, we tend to focus and worry more about the end result of a project instead of paying close attention to the individual steps needed to make it happen. It’s common to get so wrapped up in the idea of success that we forget what we are trying to accomplish will, in the end, be the sum of the work it took to get there. By focusing and paying proper attention to every aspect involved we can ensure the end result is as good as it can be. Cannabis is no exception. The goal is a healthy plant with big, beautiful buds. But there are many steps to navigate before reaching the pot of gold at the end of the rainbow. One thing that should never be overlooked or half-assed is feeding marijuana plants during the vegetative growth stage. Taking great care during this stage of the growth cycle will help increase the chances of reaching a successful flowering stage worthy of a wonderful harvest.


Nutrients Essential

Like other flowering annual plants, cannabis requires at least 16 essential elements (nutrients), in sufficient amounts, to properly develop and reproduce. Three of these elements (oxygen, carbon, and hydrogen) are accessed through the air and water. The rest must be supplied through the roots via the soil or growing medium.

Depending on soil type, the latter is typically achieved through the application of supplemental fertilization. If one or more of these elements are unavailable or only available in amounts lower than desired by the plant, growth and development will be negatively affected and the resulting yields will likely be less than if all elements were available.


Read also: Benefits, Yields, and Different Ways of Growing Cannabis

The 16 essential elements are responsible for nearly every facet of development and their absence will be noticeable. From the growth of roots and shoots to the development of flowers and fruits, a plant’s ability to have complete and reliable access to these nutrients is a night and day difference between excellent or poor performance. The elements work within the plant performing nearly every task including the building of amino acids and proteins, creating/storing energy from photosynthesis, and the synthesis of life-sustaining enzymes. These 16 essential elements are the workhorse that pushes plant growth from stage to stage.

When cannabis seeds spout, the first set of leaves are called the cotyledons. These leaves don’t look like the normal leaves that follow, which are referred to as true leaves. The cotyledons help to serve as a food source for the growing seedling until the true leaves develop and begin the process of photosynthesis. Once the seedlings have a couple sets of true leaves they can be given light feedings about once a week. Some potting soils come blended with a small amount of fertilizer mixed in, so depending on the growing medium being used to propagate the seedlings, a quarter to half strength of a fertilizer’s label rate should be sufficient to keep them growing until they are ready to start the vegetative phase. When starting with propagated clones, once the new roots begin to develop the same type of care should be given to them as was given to those that were started from seed.


After the young plants have four to five sets of true leaves, they are ready to be transplanted into a larger container where they will complete the rest of their growth cycle. The size of the container used will directly correlate to overall space available in the growing area. Plants that have more space to grow should be grown in a larger container than if the growing area is more constricted. The principal goal of the vegetative growth stage is to allow the plant to develop a strong system of leaves and stems. In this stage the plant begins to build the necessary structures needed to enter into a vigorous flowering stage. The bigger and healthier the plant can become in this stage, the more successful it will be in developing multiple flower sights that can support heavy flower production.

Read also: Transition to Bloom Phase: When & How to Switch


Nitrogen Key for Vegetative Cannabis Growth

During the vegetative stage the plant requires a base nutrient that is higher in nitrogen (N) and lower in phosphorus (P) and potassium (K). A base nutrient represents the main component of any feeding schedule and should contain most of the essential elements needed for growth. Because of adverse interactions within the formulation itself, most base nutrients will not contain any calcium or magnesium, so some type of cal-mag supplement is required. Most vegetative-stage base nutrients on the market today are labelled with names like “Grow” or “Veg” formula. In the vegetative stage, cannabis plants require more nitrogen than any other element for the creation of amino acids and proteins that give the plant a strong structure. Choose a product that has an N-P-K where the number in the nitrogen position is higher than the others (i.e. 12-6-6).

When feeding the plants, it’s imperative to start off by following the manufacture’s recommended label rates. These will provide an excellent starting point. If the label states a range of feeding rates, it is good practice to start with the lower levels and monitor over time how the plants are reacting with each feeding. If they appear to react positively, the rate can slowly be increased with each feeding but be careful to not exceed the maximum suggested rates. I have learned from personal experience it is better to underfeed than to overfeed a cannabis plant. Problems that arise from over fertilization are much harder to rectify than those caused by a plant being slightly deficient in an element or two.

How Often to Fertilize in Vegetative Stage?

There are a couple things to keep in mind when determining how often to fertilize cannabis plants during the vegetative stage. The most important is the type of medium being used. A potting mix that is fortified with organic materials and perhaps even some mineral fertilizer will require less feeding than a medium that is more inert such as stonewool. For a standard potting mix, fertilizing once or twice a week should suffice. For more frequent feedings, the base nutrient should be used at a lower rate since they’re being applied more often. It’s also good practice to use plain water between feedings to avoid the possibility of excess nutrients accumulating and causing an imbalance of elements that can lead to some of them becoming unavailable for uptake by the roots. Another thing to keep in mind is how often the medium needs to be watered. Some mediums lose moisture faster than others so the more regularly the plant is being watered, the more often it will need to be fed.

I recommend, especially for beginners, following the manufacturer’s suggested fertility program or feeding schedule. After obtaining a good grasp on how the plants grow and react to different nutrient rates, then you can start tweaking the program to improve or streamline plant development. Indoors, the vegetative stage is typically around four weeks from start to finish, not including the seedling stage.

Read also: 6 Steps to Great Big Cannabis Buds

Once again, this can vary from plant to plant and with the space allotted, but four weeks is generally about the amount of time the cannabis plant needs to develop to a size that can support heavy flowering. The general rule of thumb is to switch to the flowering stage once the plants are around halfway to the point they are desired to be when fully grown. Also, for beginner and first-time growers, I would recommend only using base nutrients and cal-mag (if needed) for the first couple runs, just get a good grip on how things work. After you are comfortable with growing through a whole growth cycle, then it’s a good time to start bringing in other supplements like amino acids, humic acids, and seaweeds, to name a few.

Pretty much every single person that gets into growing cannabis for the first time does so because they want to achieve a big, beautiful yield. But it can be a mistake to think that the end game is the only game. Paying complete and nearly exhaustive attention and care to the garden during the vegetative stage is the foremost way to ensure the plants will be ready for a successful flowering phase. There is no room for cutting corners in the quest to achieving impressive yields.


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Written by Kyle Ladenburger | Director of Regulatory Affairs for Age Old Organics & ENP Turf, Freelance Garden Writer

Profile Picture of Kyle Ladenburger
Kyle L. Ladenburger is a freelance garden writer who has worked in the gardening/hydroponics industry for over 15 years. As an avid indoor and outdoor gardener he is well versed in nearly all types of growing methods with an overall focus on sustainability and maintaining healthy soils. He holds a strong conviction that growing one’s own food is a powerful way to change our lives and our world for the better.

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