Welcome, my esteemed homeskillets. Adding macro and micronutrients to your soil is as easy as pie without bottles. If you just have a good diverse composting system, you rock. Composting things like cantaloupe rinds (basically any squash or melon rind), egg shells, banana peels, and used coffee grounds, targets your flowering cannabis needs especially well.
Here’s the thing, and the reason mainly I wanted to write this. Adding things to your plants’ soil in containers via liquids is almost always a highly destructive course for you to take. Many peeps I have helped out have been SOOOOO CLOSE to actually leveraging their living organic soil. Except a single addition (sometimes a few); they seem to think they need. Dry extracts/compounds are guilty here too.
These liquids (mistakes) usually revolve around adding micronutrients, like silicon, zinc (Zn), iron (Fe), et al. Today I have chosen a few keystone nutrients to focus on. These all bring big power, or big pain, if misunderstood. Adding macro and micronutrients like sulfur (S), Iron (Fe), magnesium (Mg), and calcium (Ca), will be addressed mainly because they all matter a lot when it comes to primo flowers. Also, a bit about potassium (K), and silicon (Si). Let’s rock and/or roll…
Adding Macro and Micronutrient Essentials
Essential Nutrients for Healthy Plant Growth
Carbon, hydrogen, oxygen, nitrogen, phosphorous, potassium, calcium, magnesium, and sulfur. I am also adding silicon to this list, as a cannabis specific nutrient. Most plants have little if any silicon, however, cannabis plants contain decent amounts of silicon in their resin. Ya follow? 😉
Generally speaking, the macronutrients are nutrients the plant uses a lot of. While micronutrients are only needed in very minute (nano) amounts. Adding micronutrients are where peeps usually get into trouble. Don’t get me wrong, adding macro and micronutrients are both subject to overdosing. Using liquids, it’s almost a given you will be overdosing, by a ton, regarding your living soil. Believe it.
Liquids are anti-microlife in two main ways. First of all, as I mentioned above, adding macro and micronutrients via “the bottle” in liquid form, adds way-way-way too much nutrient value per dosage—like ludicrously too much. Any self-contained biosphere like a living container growing cannabis, with too much food, has deadly consequences. Think, overfeeding your aquarium fish here for context. Second, organic acids kill microlife, in even small doses, a lot of them. It’s a pH swing hard and down that they can’t handle; or survive. Humic, fulvic, phosphoric (liquid P), and citric acids, are some of the main culprits here.
Boron, chlorine, copper, iron, manganese, zinc, molybdenum, and nickel. Above, when I said that plants only need tiny amounts of these, I wasn’t kidding around at all. Nano tiny. But it needs to be slow and steady in the supply chain to the plants, from the soil. Iron is specifically tricky in a liquid form, due to its nature to only be available to the plants at low pH ranges. Way lower than most bacteria can survive. So, “slamming” some iron in them costs you most of the best soil life your plants rely on for their food.
In a true living soil, iron is not a problem at all. The microbial life alters soil pH in microclimates within the container, specifically microclimates immediately surrounding the rhizosphere. This allows for various nutrients, which have variable availability under different pH ranges, to all be slowly and steadily available to the plants; all the time. Like nature intended. You use any liquids on your living soil, you can say bye-bye to that whole elegant living nutrient machine for your plants. It takes 2 to 3 weeks for your soil life to recover from such a hit.
Other Culprits of the Non-Acidic Type
Potassium, is a heavy duty “salty” mineral. When added in liquid or extract, it also drastically will alter the (containers’ soil) pH value upwards. This, also kills a lot of microlife, leaning on soil fungus especially hard. When I say “heavy duty” I mean, it is very concentrated. It is best supplied in the form of kelp/seaweed meal, greensand, and alfalfa meal, composted into your soil.
Sea salt or table salt (sodium chloride) is basically sodium and chlorine and is used as a preservative in some organic liquid nutrients. We all know how overdosing on salt can really screw us up as humans. Well, same goes for the soil life within a living container. When adding macro and micronutrients, it is also important to know what “extra baggage” elements are tagging along for the ride.
Sodium isn’t really used much, and neither is chlorine, but the microlife/plants use a touch of sodium, and chlorine additions. Both are plenty present already, in any decent soil mix. Dissolved sea salt in liquid nutrients is ludicrously over the top, regarding levels of these element/salts. Toxicity from build-up in the rhizosphere leads to a slow and ugly death; as a rule of thumb.
Adding Macro and Micronutrient Specifics
Let’s break it down, flashcard style below, shall we? Let’s have a little looksee at some of the specific nutrients I want to address in this article, sulfur (S), Iron (Fe), magnesium (Mg), and calcium (Ca). More than 95% of a plant’s mass is made up of hydrogen, oxygen, and carbon. These elements are almost exclusively supplied via air and water. Handling less than 5% of the plants’ growth, seems to suggest a very light touch, regarding other required nutrient elements. You savvy?
Also keep in mind, something like kelp/seaweed has 60+ elements contained within. Seems like a lot more elements than the plant requires. Yup. However, the enormous bio-diverse populations of microbial life in the growing containers require, and/or can make use of more elements. Like a little bit of sodium, as one example of many.
Flashcard Bullet List Ca and Mg
- Calcium: (Ca), calcium is not mobile in the plant. As such it is needed in a constant slow supply for newer growth. Ca is always in good supply mainly in the form of calcium carbonate. Things like bones, sea/oyster shells, hair, crab/shrimp shells, snail shells, egg shells, dolomite lime, limestone, diatomaceous earth, and insect exoskeletons, are some examples of many. Slow and steady available calcium also is largely supplied by the water source, when using groundwater. Many minerals contain Ca as well. If you have a Ca problem, it’s 99% a lockout, not a deficiency.
- Magnesium: (Mg), another very abundant mineral in both groundwater and soil. Mg is a mobile nutrient within the plant. So again, any Mg problem is an overdose 99%, not a deficiency. The mineral dolomite contains Mg, and that’s another reason I love using dolomite lime in my soil mixes (composted in). It brings in Mg and Ca, and buffers the pH towards neutral (7.0). Bacteria especially loves that. Overdosing Mg, gets ugly fast. Also, Mg is super harsh to smoke if still at high levels in the plant at harvest—super harsh! Fade well grasshopper.
Flashcard Bullet List Fe and S
- Iron: (Fe), the real issue with iron is always more of an availability/absorption problem, because it is usually present in the soil mix in more than adequate quantity; and in groundwater to various degrees. In a true living soil, the microlife are fully capable of making the iron in the soil and from water available to the plant. Blood meal, greensand, alfalfa, rice, and basically any dark green plant or vegetable, like spinach or broccoli, are all great Fe sources. Iron is another one you don’t want leftover in your harvested plants. It smokes super-hot with a back of the throat burn.
- Sulfur: (S), S is not mobile inside the plant. Adding macro and micronutrients never got more precarious than adding sulfur to your plants in pure dry extract, or liquid/dissolved form. Never do this to a plant’s living soil. It takes the pH down super-hard and low, laying waste to billions (or trillions) of bacteria. Best ways to make sure S is present at good levels in your soil are from composting in things like banana peels, melon/squash rinds, bat/bird guano, and gypsum, et al.
Like I said at the beginning, adding macro and micronutrients is easy. All you really need to do is be a pretty skilled at composting, using a good diversity of organic matter, and you’re covered totally. Otherwise, you can use a multitude of all-natural additions. Things like gypsum (sulfur and calcium), dolomite lime, diatomaceous earth, blood meal, bone meal, greensand, and guanos, are some of those ways. Want some killer genetics/seeds to start your adventure properly? Check out KOS!
Silicon can be brought in by things like greensand, along with others, but my very favorite way to bring in silicon is by composting (agricultural grade and up, only) diatomaceous earth (DE) into my soil mix, or adding it to compost period. Wanna check out another article by yours truly? Here ya go: Water Filtration for Container Growing – Skunk Magazine.
Last but not least, let’s never take the advice of “The Hydroshop Guy” that tells you it’s fine to use some liquid amendment/nutrient on your living soil. A: If he’s trying to sell something to you, for sure consider his motives. B: No matter how skilled of a grower he thinks he is, it’s unlikely he is savvy to the ways of true all-natural growing in living soil. Hope this was an enjoyable read, I’ll be back next Tuesday here at SKUNK. Love-ya-bye…
- Rev 😊
I'm The Rev, and I have been with SKUNK for about a decade now. I hail from Southern California, spent mucho time in Northern California, and now reside in Southern Oregon; always coastal. I am an all natural style cannabis grower and I have written a couple books on the subject - check out True Living Organics 2nd Edition on Amazon - I have been growing for over 45 years, and I have been breeding cannabis for over 30 years. Check out kingdomorganicseeds.com to see some exotic selections. Growing connoisseur cannabis is what I teach mostly, growing it in living soil without using liquid organic nutrients to feed the plant. I am also a highly skilled synthetics grower, hydroponics, aeroponics, DWC/SWC/NFT, Ebb and Flow, and soilless, but I cringe when smoking synthetic grown herbs, so for the last 15 years or so I preach the artisan style of all natural growing, specializing in container growing. Cheers and welcome aboard.