Growing Cannabis? These Are the Best Nutrients

Since there are countless nutrient options when growing cannabis, it can be difficult for an inexperienced grower to find the best choice for their plants. Arguably the biggest mistake new growers make is to turn this process into an overly complex task. Ultimately, they spend significantly more time, effort, and cash than necessary.

If you think that nutrient options are confined to marijuana plants that grow in soil, you are wrong! There are also a variety of hydroponic options, which tends to muddy the waters for the uninitiated. But fear not! We are here to provide you with a quick and easy guide to selecting the best nutrients for growing marijuana and producing fantastic yields.

What Elements Does a Marijuana Plant Require for a Successful Growing Cycle?

Hydrogen, oxygen, and carbon are considered non-mineral essential plant elements and are taken up by the plants in either gas or vapor form. In ideal growing conditions, fresh air and water will provide ample Hydrogen, Oxygen, and Carbon., which are of course the basic building blocks of life.

There are 17 essential mineral elements for plant growth that are broken up into macro and microelements, or “nutrients.” The macronutrients required for plant growth are:

  • Nitrogen
  • Phosphorus
  • Potassium
  • Sulfur
  • Magnesium
  • Calcium

The first three nutrients listed above – Nitrogen (N), Phosphorus (P), and Potassium (K) – are the most crucial. If you purchase a bag of nutrients from a store, you should notice an N-P-K ratio listed on it. The ideal ratio changes throughout the growth cycle of your marijuana plants. For instance, you need a higher proportion of N and K to P during the vegetative stage. A general rule of thumb is to remain close to a 3-1-3 (N-P-K) ratio for the first few weeks.

During flowering, it is best to reduce the proportion of Nitrogen to Phosphorous and Potassium compared to the ratio used during the vegetative stage. It is essential to lower the proportion of N at this point because it can reduce bud development and promote vegetative growth instead of generative (also known as flowering) growth.

Maintaining higher proportions of P and K is critical when flowering because the plants are using larger amounts during this stage of growth than they did during the vegetative stage.

Additional Information About Cannabis Nutrient Deficiencies

Please note that the majority of nutrient deficiencies are due to excessively high or low pH levels in your water. Ideally, soil-grown marijuana plants will have a pH of 6.0-7.0. The range drops to 5.5-6.5 if you use coco coir as a growing medium, or if you are growing hydroponically. When the pH is at the wrong level, it reduces the plant’s ability to absorb the nutrients you are working so hard to provide.

Calcium and magnesium are often overlooked when discussing the growth of the cannabis plant. It is common to find them together in a single Cal-Mag supplement which normally contains Iron as well. These three nutrients are important to the process of photosynthesis, which involves creating energy from light. Magnesium is particularly important for photosynthesis; it is the central atom in the chlorophyll molecule.

While marijuana plants don’t need a large amount of sulfur, it is still considered an essential macro element. As well as aiding enzyme formation, it helps to construct proteins. Sulfur is also pivotal in the development of chlorophyll molecules. If your plant is deficient in Sulfur, Calcium, Magnesium, or Iron, it can display symptoms such as yellowing or dying leaves.

Besides the macro elements, there are several more elements needed in much lower amounts. While you don’t need large amounts of microelements, a deficiency in any of the following will negatively impact the health of your plants:

  • Iron
  • Zinc
  • Molybdenum
  • Copper
  • Cobalt
  • Boron
  • Chlorine
  • Manganese

What are Hydroponic Cannabis Nutrients?

The hydroponic growing process involves growing marijuana plants without soil as the growth medium. Instead, you use a different substrate such as clay pebbles, rockwool, or coco coir. Hydroponics is becoming an increasingly popular method of growing marijuana because it offers a high potential yield in a small amount of space.

The soaring popularity of hydroponics has led to the majority of nutrients sold for cannabis cultivation to be soluble fertilizers that are ready to use in hydroponic systems. Such products consist of concentrated mineral salts available in powder or liquid form. Regardless of the option you choose, you must dilute the nutrients in the water to the correct concentration before applying them to your plants.

There are separate products available for the vegetative and flowering stages that contain different N-P-K ratios. For vegetative growth, choose a fertilizer with a higher proportion of nitrogen and potassium to phosphorous. When your plants are flowering, decrease your nitrogen concentration and increase the proportion of phosphorus and potassium.

One problem with hydroponic nutrients is that they can be very unforgiving if the incorrect dosage is applied. Follow the recommendations on the fertilizer bag or bottle and frequently check the pH to ensure it is between 5.5 – 6.5.

Now, let’s take a look at fertilizer usage when using one of the three most popular hydroponics growing mediums.


This light and inexpensive mineral is known for its water retention abilities. It consists of a silica compound and basalt. You can buy it shredded, in small cubes and blocks, or in large slabs.

If you purchase rockwool, remember that it is an alkaline medium before it is conditioned with a lower pH solution. To condition the blocks before plantng into them, soak them for at least an hour in water with a pH of 5.5. In rockwool, the elements you provide in the nutrient solution will be immediately available to your plant for growth.

Coco coir

This coconut fiber is a natural choice for a growing medium. It is made up of a coconut husk, the substrate used by coconut seeds to help them germinate. Coco coir does an excellent job of retaining minerals and water. Its water retaining abilities are akin to Rockwool, but it is recyclable and doesn’t cause damage to the lungs when inhaled.

Coco coir has a pH of 6.5 – 7.0 which is very close to that of unfertilized soil. It is becoming increasingly common to add up to 30% perlite to Coco coir in order to increase aeration around the root zone. Overall, it does not have the buffering capacity that soil does, but it is more forgiving than alternative growing mediums. Ideally, you will keep the pH of your water and nutrient solution between 5.5 – 6.5 when using coco coir.

Growers recommend nutrient brands such as Dutch Master and Canada Advanced Nutrients when growing marijuana plants in coco coir. One final thing to note: coco coir doesn’t retain calcium particularly well, so keep your eye out for any deficiencies and consider supplementing with extra calcium at all stages of growth.

Clay pellets

Unlike rockwool or coco coir, clay pellets don’t retain water well. However, you’ll find it easy to cycle nutrients and water through without the age-old concern of overwatering your marijuana plants. The gaps in clay pellets are ideal passages for nutrients and oxygen which results in a strong root system. Best of all, clay pellets are reusable, so you can save money in the long term.

Soil Nutrients vs. Organics for Cannabis – Which is Best?

The main difference between soil and the growing mediums used in hydroponics is the existence of organic matter such as manure, worm castings, compost, and hummus. The majority of the essential elements contained in organic matter are only available in a non-soluble form. This means they have to be processed by the microbes and fungi that live in the soil for them to be available for plant uptake.

Non-organic fertilizers can be a quick and easy package to increase soil fertility for outdoor and indoor grows. However, these fertilizers can build up in the soil rapidly and diminish the quality of the soil. The buildup of these fertilizers can reduce a plant’s capacity to absorb water and nutrients.

In contrast, organic nutrients and fertilizers contain fewer soluble nutrients and help promote soil health by feeding the microbes and fungi that live in the soil.

Creating an Organic Fertilizer

A simple and cheap way to create your own fertilizer is to use organic inputs such as fish meal and blood meal (both are high in Nitrogen), kelp meal and wood ash (high in Potassium), bat guano and bone meal (high in Phosphorus), dolomite lime (high in magnesium and calcium), and Epsom salts (high in sulfur and magnesium).

If you’re able to mix these ingredients in the right amounts, your main tasks during the growth cycle will be watering your plants and adding carbohydrates to feed the microbial communities that occupy your soil. You can purchase pre-mixed organic fertilizers, but these can be more expensive than mixing your own.

Organic growing is dependent on ensuring there is a healthy level of essential elements, mycorrhizae, and soil microbes in the soil.

There are a remarkable number of ways to grow cannabis. Some involve hi-tech equipment, while others require vast experience and skill. Although it is tempting to dive into the latest fads, it is important to remember that humans have been growing and cultivating marijuana plants for thousands of years using little more than water and whatever organic matter they could add to the soil.

Organic soil is recommended if you’re a newbie since it is more forgiving than growing hydroponically. Hydroponic nutrients help you produce enormous yields but require more time, expertise, and attention. Above all else, analyze how much time and money you can afford to use when growing your marijuana plants. This is time well spent because it will save you time and money on products you won’t ultimately use.