Preface
What's up growers and Cannabis enthusiasts! As a professional caregiver and growing consultant in the great medically compliant state of Michigan, and overall friendly guy on the internet; I tend to field the same handful of questions involving super soil, improving yield, and organic feeding (compost teas, top dressings, soil recipes). It made making this seem like the prudent thing to do!
A couple of disclaimers...
First and foremost, this is a beginner's guide to organic cannabis growing, based off my experiences with multiple technique's. Im not a botanist by any means, but I do my best to explain why I do what I do (in a simple stoner's terms), so that you can understand a few different ways to meet your plant's needs and find what works best for you. It is not a no til guide, I do recommend reading about no til. And any and all ways to grow. Experiment as much as you can. Take notes. Compare notes. I do my best here to give you a bullet proof guide for success, but this isn't the only way. I'm always trying to learn more and improve. I suggest you do the same.
Part 1: "The Shade"
I won't spend too much time here because I can just link to a blog that I would be paraphrasing from anyway. Super Soil... here's a nice little blog post you can read about why super soil is full of faults...
http://buildasoil.com/blogs/news/12533881-whats-so-cool-about-super-soil-the-super-soil-recipe-breakdown
Now that we've tore apart subcool's super soil recipe, let's talk real quick about water only soil mixes and container gardening. Most people attempting a water only approach (even with a good recipe) find themselves needing to add a little of something or other at some point, or find their yields disappointing. No til gardening is definitely a viable solution, but again, this isn't a no til guide. The solution that I'm gonna talk about...is a mix of a balanced amended soil (without "cooking"), with readily available fertilizer occasionally applied in waterings.
Can you substitute bottled "organic" nutrients for some of the dry bagged ones you ask?
No! Not ever I say! You're cheating yourself out of fresh biological activity and you deserve better!
Alright, that's enough of my naysaying!
Part 2: Building Your Base Soil
This is simple enough. Peat moss or Coco coir/aeration/compost in even parts.
For example:
One gallon of peat moss or coir, one gallon of compost, and one gallon of aeration.
What you mean by aeration dog?
Perlite, volcanic rock dust, Google for more...basically something to ensure you will have heavy drainage.
Have some fox farm or promix that you used in your previous grow and would rather start with that as a base?
You totally should! Always make use of what you have before you buy anything else. If this is spent soil from a previous grow it will probably have a comparable consistency to a mix of peat moss and perlite. Add in even parts compost and that'll give you the same solid mix.
What kind of compost should I use?
All of the kinds of compost!!! Grow stores are so limited, most will usually have over priced forest floor compost and worm castings at best. Your big box stores with garden centers, tractor and farm supply stores, and landscape supplier's will provide more affordable options. Google if there's a local compost facility in your area. Thatd be even better.
Cannabis is an annual so it prefers bacterial dominant soil. Worm castings and thermal made compost (compost with lots of foods scraps, leaves, and coffee grounds to create a hot compost pile) will provide this.
Fungal heavy compost (found in compost broken down without heat); made from just wood chips or the forest floor, plays an important role is well. Leaf mold compost (also cold broken down) is great too, it's super rich in humus and minerals. Fungal microbes play a major role in phosphorus uptake so you want at least
Worm castings of course are the best of all...especially of you can homemake them.
A nice blend of bacterial compost, a forest floor or fungal heavy compost, and worm castings will be best. But if you have to settle for one, you'll be okay. Just the more diversity you can have in your soil the better.
Part 3: Nutrients, and Amending Your Soil
I won't go full on essential plant nutrient lesson, it's covered in many other guides. I'm assuming a level novice knowledge has been acquired before reading this guide.
We want to build a soil that will have all the nutrients the plant needs, readily available when the plant needs it. Organic growing is not the same as growing with bottled nutrients where you apply and the nutrients are already chelated and ready for uptake by the plant roots. Growing organic, you already have everything in the soil, the roots send out exudates that communicate with the microbiology in the soil, and the microbiology breaks down the organic matter in the soil to be uptaken by the plant. If you want to know more of the details of this relationship I highly recommend checking out the book Teaming With Microbes.
So what nutes do we want in our soil and how do we provide them?
I'm gonna start backwards with the micronutrients. Boron, copper, manganese...these should be plentiful in your soil with little effort. No need for extra amendments to provide these typically.
Calcium, magnesium, and sulfer, while still micronutrients, are much more needed by the plant. In particular calcium and magnesium. The good news about sulfer is that it's usually provided when you're providing something else. So there's no need to amend for sulfer typically. Now magnesium is available in compost, castings, so there's some in the base mix but adding some is usually needed, especially in container gardening. Which most indoor cannabis is. Calcium, could almost be a macronutrient with how important it is. It is also available to the plant from compost and worm castings but we will want to amend the soil further and apply some additional love throughout the grow.
Onto the big three boys. Nitrogen, phosphorus, and potassium. NPK. Cannabis uses lots of nitrogen in veg, and lots of phosphorus and potassium. This has misled synthetic growers, who have to feed the plant directly, into not supplying adequate K during veg (although not often), and cutting off the supply of nitrogen too soon into flower. And everyone always overdoes it with phosphorus...Google peak phosphorus... A good NPK ratio for cannabis soil (tomato's, and pepper's love this as well) would be something like 5-2-3 (these numbers are pretty arbitrary just trying to give you an example). Lots of nitrogen, more than anything, it is your biggest building block...however...over doing it can inhibit root growth and delay maturity. That's why phosphorus needs to be not too far behind nitrogen. And since we want big fruits to come from those big roots, and we want a strong, sturdy plant...we've got potassium.
Growing organically, we don't have to feed the plant directly. We make sure the soil is good and prepared, and its microbes and the roots talk to make the magic happen.
Now, in my gardening I noticed that while building a solid soil yielded positive results, quantity could use some improvement. Even when I composted my amendments into my soil (commonly referred to as cooking in super soil circles). Growth rates and yields were a little disappointing.
Adding readily available sources of macronutrients, along with amendments that provide growth hormones and trace minerals (alfalfa and kelp meal) in addition to having a prepared soil was where I found my salvation. I did some grows where I simply applied the readily available macronutrients and beneficial amendments into a unamended soil and it had some deficiencies, and performance issues.
The plain water approach vs the just tea approach was no match for the two of them combined.
