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Organic vs. Chemical Cannabis Fertilizers for Your Grow

December 6, 2016
Cannabis plants are resilient and resourceful. However, much like any other living organism, cannabis plants need nutrients. Also known as fertilizers, nutrients can be either organic or inorganic (chemical).

Before chemical fertilizers, traditional farming practices required you to keep the soil healthy and rich in nutrients by either using nitrogen fixers such as leguminous plants (e.g. beans, peas) as cover crops or by spreading manure. These were the basic methods used for centuries to keep gardens productive.


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Then along came a new style of modern day farming. It was shaped in 1840 with a publication, Chemistry in Its Application to Agriculture and Physiology, by Justus Von Liebig. This book introduced the concept of N-P-K (Nitrogen, Phosphorus, and Potassium) as the essential nutrients needed for a healthy plant. However, creating these nutrients chemically was costly, especially nitrogen.

This all changed at the start of the 20th century due to a discovery made by Fritz Haber. Fritz figured out how to fix nitrogen from the air and then combine it with hydrogen pulled from natural gases to create ammonia. Ammonia then could be produced and used as a nitrogen fertilizer at a very low cost.

Today, there is continual debate around which type of fertilizer is the right choice for your cannabis plants. Both methods can produce quality product, but they each have disadvantages to consider as well.

Organic Cannabis Fertilizers

Organic fertilizers are described as nutrients that come from organic sources such as animal and vegetable waste. They also extend to sediments like glacial rock dust and gypsum that contain beneficial minerals for the soil and plant.

The benefits of organic fertilizers:

  • Slow release of nutrients protects the plants from overfeeding/burning
  • Overtime organic fertilizers can improve the quality and diversity of life in your soil
  • Improved airflow and water retention in soil
  • Renewable and sustainable
  • Organics stay in the soil with a lower chance of nutrient run-off

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When working with organic fertilizers, you are given the opportunity to improve your growing medium while at the same time improving the quality of your flowers. The benefit from organics largely comes from the ability to nurture this balance. Growers often find that growing organically increases the flavor profile of the cannabis as well as the yield.

Another substantial benefit comes from the fact that this fertilization process can repeat itself year after year as the soil continually improves. This makes using organic fertilizers a popular choice for outdoor gardeners who use the same soil repeatedly. Using organics is also preferred for those who want to be more aware and in tune with their natural environment. Organic fertilizers are readily available from renewable sources, and when applied, they ground down in the medium, preventing nutrient run-off and thus making organic fertilizers the earth-friendly option.

The disadvantages of organic fertilizers:

  • Take time to be absorbed by the plant
  • Require microorganisms to break down the nutrients which may slow in colder temperatures
  • Can introduce insects and pests
  • Costly

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There are complications and difficulties that come from working with organic fertilizers. For example, when faced with a nutrient deficiency in the middle of flowering, adding nutrients from organic fertilizers might not work as quickly as desired, leaving the plants damaged. Also, organic fertilizers can sometimes introduce pests into your garden which can be difficult to handle, especially indoors.

Chemical Cannabis Fertilizers

Yellow gloved hand holding a green scoop with fertilizer

Chemical fertilizers are synthesized and extracted to a specific chemical form. The nitrogen comes from the aforementioned Haber-Bosch process. Phosphate and potassium are extracted from minerals, and other impurities that can harm the plants are removed. The results of these extractions are highly refined specific quantities of N-P-K nutrients.

The benefits of chemical fertilizers:

  • Exact nutrient ratios
  • Increased growth and THC production
  • Rapid nutrient uptake
  • Affordable and widely available

The main benefit of using chemical fertilizers lies in their precise ratios of nutrients that can deliver big results in terms of yield. When applied to your garden, they are readily available and can start to impact a plant’s health immediately. The specific ratios of different fertilizers allow you to customize what works best for individual strains, leading to higher yields and THC contents.


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The disadvantages of chemical fertilizers:

  • Do not feed into the development of the soil
  • Can burn and kill plants by overfeeding
  • Leech from growing medium, impacting surrounding environment
  • Produced from non-renewable resources

Chemical fertilizers do have downsides. Because the nutrients are readily available, they can also burn and kill a plant by overfeeding. Also, these readily available nutrients do not add to the quality of soil before being used by the plant, leaving the soil quality diminished. Weakened soil quality allows for nutrient run-off to occur, which wastes nutrients and can negatively impact the surrounding environment.

Lastly, these chemical fertilizers are not produced by renewable resources. Producing nitrogen is an energy intensive process that takes a toll on the environment especially as climate change and environmental issues become more pressing than ever before.

Other Considerations

hemp,cannabis soil and fertilizer

hemp,cannabis soil and fertilizer

A good analogy for organic and chemical fertilizers is the comparison between baking and cooking. Organics are like cooking. You can take away, add, and alter the recipe and find a unique delicious meal at the end of the day. Chemical fertilizers are like baking. You know what you have, and if you know what you precisely need you will end up with a beautiful loaf of bread. If you stray from the recipe, however, problems will arise.

Of course, the goal of any gardener is to produce the highest quality product, but it should be noted that as cannabis production increases in scale, there’s more room for nutrient run-off, environmental impacts, and resource depletion. Thankfully, the cannabis community has a lot of forward-thinking individuals, and as the industry continues to develop, there’s a lot of opportunity to look at what can be done to make this crop as sustainable as possible.

Trevor Hennings's Bio Image

Trevor Hennings

Trevor is a freelance writer and photographer. He has spent years in California working in the cannabis industry.

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  • Byrond2

    I’ve been growing in Oregon for several years. Consider that Sativex is made from plants grown in organic compost. They can’t use conventional hydroponics because synthetic nutrients are refined chemicals that are taken up by the plants. Thus, the nutrients become a chemical contaminant. Similarly, conventionally grown vegetables can have very high nitrate levels due to nitrate fertilizers. That is not desirable or healthy. The key to using organic potting mix or soil is to make sure that it’s been inoculated with various beneficial microbes. These ensure that nutrients can be broken down and utilized as needed by the plant. Also use liquid nutrients or teas made of worm castings, guano, minerals, fish products, and kelp. These will be readily utilized. What works for me (outdoors or indoors) is this: Use 5-gallon fabric pots, never regular plastic pots. Get a high quality organic potting mix that has some nutrients but not enough to burn or otherwise harm young plants or seedlings. Fill the pots to the top. Wet each pot with one gallon of filtered water. The water should be 75 degrees F and I add Bacillus subtilis biofungicide as well as a tiny amount of fish fertilizer with kelp. Then I plant a seed in each pot. If the pots aren’t set outside in nice weather, they’ll need to be kept warm and free of mold, which may mean having a 6-inch fan blow over them (without blowing cool air directly on the surface of the soil), and a HPS lamp or UV-emitting T5 shining on the soil. I’ll cover the seeds with some tented cardboard in this situation for a few days to keep the light out but still allow air circulation. After this, organic liquid fertilizers can be added as recommended. Such as, two tablespoons organic liquid grow fertilizer a few weeks after germination, then transitioning to liquid bloom fertilizer. One note of caution, if the bloom fertilizer is made of powdered bone meal, it can readily fill the gaps/pores in the surface of your potting mix and basically make something akin to a plaster seal that prevents air and water from permeating the surface of the soil. This is not good.

  • Alex Dubois

    The article mentioned several negatives regarding the use of organic fertilizer. They are:
    Take time to be absorbed by the plant
    Require microorganisms to break down the nutrients which may slow in colder temperatures
    Can introduce insects and pests

    If you use a product such as MightyGrow Organics 4-3-4 which is already inoculated with beneficial microbes that facilitate the breakdown of the slow release nutrients in the fertilizer. The MG fertilizers are all triple pasteurized so there is NO possibility of insects or disease. Almost half of the nitrogen and all of the P&K is available the first year, so there are plenty of nutrients for the plant to absorb, especially if you add myco to the rooted cutting. And as for cost, it is actually LESS expensive to use organic fertilizers than synthetic ones, especially if the organic fertilizer is fortified with trace minerals like the MG products are. The trace minerals provide the plant with ALL the nutrients it will need to make the good stuff – THC. I realize this sounds like an ad for MightyGrow, and it is to an extent, but the truth of the matter is that when you consider the fact that you can recycle your growing medium for grow after grow, any nutrients in the fertilizer that are not taken up in one grow will be available for the next. This is both cost effective as well as environmentally friendly and sustainable.

    I have growers in CA and CO that are pushing 30% THC using my fertilizers as PART of their growing system. These are VERY good growers who have switched from the nutrient program they were using to now they rely on MG for all of their NPK inputs and soil minerals. What do they know that you don’t? 😉

    • Trevor Hennings

      I am with you on the organics Alex and everything you are saying goes with my personal experiences growing. The farm I worked on for years practiced organic techniques and we developed resilient beautiful strong healthy plants. Just trying to offer a comparison article without too much personal opinion.

      Cheers to your organic farming and to all who are out there working with the natural system.

  • Lenroc

    I think that a major consideration when buying cannabis fertilizers should be the amounts and the nutrient concentration in the solution and consistency of the materials used to produce it. With new brands that sprung up overnight and even organics I think this varies from bottle to bottle so its hard to get consistent results.

    The majority of cannabis fertilizers I tried were overly dilute; and some of the fertilizer companies artificially increase nutrient concentration and add amino acids, vitamins, sugars or enzymes that inflate cost but are not proven to affect crop yield and sometimes even push your crop the other way.

    Also, many elements in marijuana fertilizers are not entirely in ionic form, making them unusable by the plant – this applies both to organic and chemical… If you think about it, pure chemical avoids the issues of feeding sugar (which the microbes feed on if they are still alive by the time you get your bottle) to your plants, pasteurization also will kill microbes and if they are inoculated later, how do you know they are still alive, has the store bought it recently? or was it kept in the back room since last summer? was it kept at the proper temperature?

    Lots of unknowns, not to mention that there are a number of factors that can come into play even if the colony of microbes survived the transport and storage – like will the colony of microbes be able to colonize, compete with existing microbes and survive the ph shock between your soil and the solution they’ve been in. PH too high or too low it will kill the colony and then you have to deal with microbial toxins, and other nasty stuff negatively impacting your crop… I guess one of the best pieces I have see on microbes is from a study at Texas A&M University… check out FAQ #6 – not to even consider the fact that in a completely controlled environment and solutions and viability of the colony of microbes freshly inoculated at the university they were not able to really get good results.

    I prefer to go with something that is a clean ionic formula like Cogo’s Original Cannabis Fertilizer ( that gives me exactly the rations needed without the high volutant prices, and I get large, predictable crops each time.

    Don’t take me wrong I experimented with all kinds…believed a lot of hype and marketing, spent a lot of money when I started, but I learned it does not need to be like rocket science to use 20 some different formulas during growth, 10 others during flowering… lol.Been doing this over 10 years and still laugh about the new marketing gimmicks.

  • Nice Article…!.Both compound and natural manures are extremely valuable for the development of plants.Organic composts is the plant , creature arranged or blend of both. Though in the event of synthetic material that contains plant made item that are additionally added into the dirt to bolster plant.both are useful for plants.Suppose in the event that you need purchase best fertlizers for your plants then visit:(

  • E.L. Bl/Du

    lets not forget about the r un off that chemical fertilizers do because they are NOT absorbed as readily as organic fertilizers. In addition this run off KILLS FISH and wildlife (and humans) by leaching the oxygen out of the water causing large dead zones in our oceans, streams and lakes. It is HORRIBLE for the enviroment and is considered poor farming practices. (FDA knows they got this one wrong but Monsanto is in kahoots with them to hide these facts (recent emails were uncovered between the CEO of monsanto and FDA) and using the same BS the tobacco industry used for over 40 years with ghost writers and lots of money to cover it up.