March 25, 2022 | In The IGG Blog

Fertilizer Options for Your Grow Operation: What You Should Know

With more and more states legalizing weed, more and more people are jumping into the industry to grow it. The unsurprising result is more demand for all products necessary for cultivation, particularly fertilizer. And that creates a supply issue for two reasons: one, more demand means the need for more supply; and two, many important ingredients in fertilizer products – such as phosphorus and calcium – are finite resources (and becoming more finite by the day). Lower amounts of phosphorus and calcium in the plant food leads to diminished yields in the plants themselves. 

In addition, organic ingredients are also becoming harder to source. Bat guano, for example, is no longer sustainable to use because so much has already been taken from the environment. PLUS, bat numbers are dropping so less guano is being produced to begin with.  

Less access to certain ingredients inevitably leads manufacturers to search for substitutes for the nutrients and minerals they can no longer source.  

As a result, fertilizer prices are going up, up, up, and supply (and, in some cases, quality) of products is going down, and cannabis growers are scrambling to find the best solution to balance producing optimal crops while not breaking the bank on fertilizer to grow them.  

When it comes to cannabis cultivation, fertilizer is HUGELY important. Not only do cultivators want to choose the best option for optimal yield and quality, but they also need to consider the nutrient levels for the plants at different stages of the growing process. Even the type of fertilizer itself makes a difference.  

Not to fear, though. We have plenty of options available at different price points.  

Plant Nutrition 101  

Plants require three levels of nutrients: primary, secondary, and micronutrients.  

Primary Nutrients 

Primary nutrients are the nutrients plants use in the largest amount, which include carbon, hydrogen, oxygen, nitrogen, phosphorus, and potassium. These nutrients assist in major plant functions:  

  • Growth of foliage 
  • Fruit 
  • Root 
  • Flower 
  • Protection against diseases  

Hydrogen, oxygen, and carbon come from air and water, but nitrogen, phosphorus, and potassium must come from some sort of substrate. In the case of soil-less growing, that means they must come from fertilizer.  

Secondary Nutrients 

Secondary nutrients are needed in smaller amounts but are just as important to overall plant health. They are magnesium, sulfur, and calcium, and they are often boosted by soil amendments. 


Micronutrients are nutrients the plant needs, but in far smaller quantities. These include zinc, iron, boron, manganese, chlorine, copper, molybdenum, nickel, and cobalt. These can often be found in soil amendments. 

NKP and Fertilizers 

NKP stands for nitrogen, potassium, and phosphorus, all of which are integral for cannabis growth. However, each stage of growth needs different levels of each nutrient, so a one-size-fits all fertilizer such as Miracle-Gro will likely burn your plants with too many of the wrong nutrients at the wrong time.  

Cannabis fertilizers feature customized NPK ratios specific to the cannabis plant, which provide maximum effectiveness to promote factors like root strength, ideal top growth, and healthy development overall. For example, you need enough phosphorous and potassium (PK) in your growing process to produce big flowers which then produce larger yields.  

However, because of supply problems, we are seeing reduced amounts of P and K available, which translates to seeing smaller flowers and lower yields. 

Synthetic Fertilizer, Organic Fertilizer, and Soil Amendments – What’s the Difference?  

Depending on which option you choose (soil or soil-less) for your cultivation, you still need to know what your plants are ‘eating.’ Does your soil include enough of the necessary nutrients, or do you need to add more? Or, if your cultivation method is soil-less, how are you getting the necessary nutrition to your plants? This is where fertilizer and soil amendments come into play. 

Typically, fertilizers deal with the level and quality of nutrients in the soil, while soil amendments deal with the quality of the soil’s texture. While soil amendments do contain nutrients as well, their main function is to improve soil texture.  

Synthetic Fertilizer:  

These are chemically manufactured materials that include one or more of the primary nutrients and affect the plant directly by boosting nutrients in the soil. 

Organic Fertilizer:  

These are derived from naturally occurring materials (manure or guano, for example) that include a significant amount of one or more of the primary nutrients. Many also include organic matter, which means they can also be classified as soil amendments. They can affect the plant directly or indirectly, by boosting nutrients in the soil and/or improving the soil texture. 

Soil Amendments:  

These can be naturally occurring materials but can also include chemically manufactured products, like gypsum. They affect the plant indirectly by modifying the soil as they decompose which then indirectly affects the plant. Growers use them as an alternative to chemical fertilizers (as a note, they can act as fertilizers as well). They come in two types: mineral supplements and/or organic nutrient meals. For an in-depth look at organic soil amendments, read more here. 

Source: University of California Agriculture and Natural Resources 

Is One Better Than the Other? 

Honestly, not necessarily. At the end of the day, what really matters is that whatever you use positively affects the plant. The plant doesn’t care about what kind you use, only that it provides the right amount of nutrients the plant needs to properly thrive.  

That said, though, sustainability is an extremely important factor for being a responsible cannabis cultivator, so we always suggest choosing an option that is eco-friendly.  

Cannabis Fertilizers We Recommend 

With necessary ingredients harder to come by, demand going up, and prices on what’s available increasing, companies are resorting to raising their product prices or cutting corners (or, unfortunately, doing both). For instance, some manufacturers have turned to replacing salt with fillers like PK boosters. The main issue with fillers is that they often lead to less potent and effective fertilizers, which lead to lower and less potent crop yields.  

We don’t believe in cutting corners, though. That’s why we continue to stock a variety of excellent fertilizers and soil amendments from top brands who believe in maintaining the highest quality products. To help you choose what might work best for your needs, we’ve highlighted some great brands we recommend to ensure your plants the best chance of not just surviving, but thriving: 

No matter which fertilizer you choose or whether you go the organic route or not, you can be sure you’ll find all the fertilizer supplies you need on our website.