At the bottom you will find some detailed information on a newer potting soil recipe I have been using for a few years now (my preferred mix!). But I wanted to throw in a couple others that I’ve used for many years so anyone reading this has some option and flexibility and can see the progression of how and why I ended up on that soil blend.
It is not about any one ‘recipe’ being correct or better than the other but rather about what works best for you and your locale while keeping in mind the basic underlying fact that will make or break any potting soil. Organic matter + minerals!
After taking many years figuring things out, this was the soil recipe I landed on a decade ago and have used many many times and you will see variations being used all over.
Equal parts (1:1:1) Canadian Sphagnum Peat Moss : Compost or Castings : Pumice or Lava Rock
To this base soil then add per cuF:
1/2-1 cup Kelp Meal (loaded with nutrients, enzymes and hormones)
1/2-1 cup Neem Meal (loaded with nutrients, specifically sulphur, and pest prevention compouds)
1/2-1 cup Crab Shell Meal (calcium and chitin)
4 cups Rock dust (volcanic, basalt, granite or glacial)
4-8 cups biochar
The next generation of my soil mix completely removed the amendments (kelp, neem, crab) and instead increased the rock dust component as well as biochar, and rearraged the base soil mix and looks something like this:
40% Peat Moss
40% Compost or Castings
20% lava rock / Pumice
Per cuf then add:
8 cups rock dust
8-12 cups biochar
This recipe worked and works equally as well if not better especially in terms of longevity of nutrients in the soil because of the nature of rock dust and nutrient cycling in a living soil that is mulched and cover cropped.
Below you find the mix I currently use which essentially removes the aeration component (pumice) and relies on soil life constantly turning over and aerating the soil along with roots that live and die and move water and oxygen throughout the soil. In a true NoTill Garden whether in the soil or in containers, no phsyical aeration component such as pumice is needed, simple as that!
So with the above info and the below details you should be able to find which recipe or a variation of your own that will work best for you! Please please please, as always EMAIL ME with any questions so that I can continue to provide updates here with information you would like to see or want better clarification on! Thanks!!
‘NoTill Gardening’ Soil Mix article:
Today you’ll find a short discussion / introduction to the latest evolution of our soil mix. This has been greatly postponed as I was hoping to incorporate research into the main components here, but the breadth of that discussion is overwhelming and in fact turning into a long term consolidation and interpretation of a vast collection of both field & lab studies coupled with my usual hands on experience/observations. Expect details at a later date - an overview below.
50% Sphagnum Peat Moss
8 cups per cuF Rock Dust
(Handful of worms per pot/bed)
50% Sphagnum Peat Moss:
(Alternatively, coco coir amended with 1/2 cup gypsum per cuF to account for the absence of Sulphur). Coir has a lower CEC, is inert & contains no Sulphur. It is inherently inferior to sphagnum peat moss at face value but in taking the appropriate actions as noted above and proper long term soil care, this fact is of little consequence.
Sphagnum peat moss not only contains nutrients but is also full of bacterial and fungal life including mycorrhizae.
This can be in the form of Thermophilic compost, worm castings/vermicompost or leaf mould. Sourcing quality humus is key to growing vigorous and healthy plants from the beginning. A favorite variation on this portion is to use existing well used ‘notill soil’ which over the course of a few to several years literally becomes pure worm castings!
Biochar has a laundry list of benefits and will have an article all to itself in the future. Again, source quality char made properly via pyrolysis and for general agricultural purposes it should be made in the 250C-400C temperature range. Biochar retains 10-12 times its weight in water (think: drought tolerance), stimulates microbial growth and diversity in the all important rhizosphere (increased yields), acts as a ‘reservoir’ for nutrients thus reducing ongoing fertilizer requirements. Incredibly porous increasing Oxygen content in the soil, and of course sequesters carbon.
4-8 cups Rock Dust per cuF
Per cuF of the above base soil mix we then add 4-8 cups of volcanic rock dust (agrowinn volcanic rock dust, available right here). Rocks and their eventual dissolution (hence, ‘rock dust’) is the original source of ALL nutrition on earth, minerals! Aside from the fact your compost/humus portion is indeed loaded with nutrients the rock dust is your ultimate source of nutrition / minerals and via the approach of NoTill Gardening you will never need to re-amend this soil!
I like to use this phrase to most simply sum up why this basic soil mix covers all your bases: “Rock dust is the source of nutrients, Humus is the delivery system.” Soil life feeds off the rock dust and in turn makes it plant available. The closer your source of rock dust is to the consistency of powdered sugar the quicker they become available (from day one in that case). Through the exchange of plant root exudates the microbes living in the rhizosphere are able to deliver the elemental minerals derived from the rock dust directly into your plants.
An incredible biological process is in place that encompass’ what we simply refer to as ‘soil.’ The philosophy of NoTill Gardening as I have developed stemming from the concepts of Masanobu Fukuoka’s ‘Natural Farming’ is based around the idea of maintaining, caring for and encouraging these natural process’ already occurring in the soil. It is about tapping into the process that has developed on this planet as the source and the ability to continue all life on Earth.
There are just two main focal points in caring for your newly placed body of ‘notill’ soil (and a third supplementary). Cover crops, and mulching. Both of these topics are discussed at length below in prior articles.
Lastly is a supplement that also covers the very important aspect of IPM (Integrated Pest Management). Along with the soil mix above we recommend a regular once weekly foliar spray to keep pests in check / at bay, which becomes especially important when growing indoors or in enclosed greenhouses where the lack of biodiversity (predators) can allow for the quick reproduction and ensuing infestation of pests. See the “About our products” section for further discussion on the Tonics we make and recommend for both a nutrient supplement and regular IPM maintenance and how they can also help with increasing a plants natural pest resistance (SAR/ISR).
Please email any questions you may have and over time I will update and expand this article as needed
2 parts Peat Moss
2 parts coco coir
1-2 parts worm castings
Option but often desired: 1 part perlite or pumice
A light soil mix that can be fertilized once or twice monthly with our Botanical Tonics or any liquid fertilizer for that matter.