Is My Potting Soil Too Hot? Commercial Soil Analysis

Teddy Edwards

420 Support
420 Staff
Analysis by cbdhemp808 :thanks:

What is the best NPK value for potting soil for growing cannabis? Some quick googling, maybe not accurate...

0.030 - 0.006 - 0.022 (veg mix)
0.007 - 0.010 - 0.020 (flower mix)
0.025 - 0.008 - 0.030 (all-purpose mix)

So, these commercial potting soils – FF and SOHUM – would appear way too high in NPK.

Here's SOHUM compared to a hypothetical best "all-purpose mix":

SOHUM...... 0.500 - 0.500 - 0.250
ALL-PURP... 0.025 - 0.008 - 0.030

From this, the SOHUM looks to be too hot by a factor of: 20 - 63 - 8.4

For that matter, Happy Frog would also be too hot by a factor of: 12 - 38 - 1.7

Now let's compare ALL-PURPOSE to a premium cannabis potting soil...

BUILD-A-SOIL 3.0: 0.95 - 1.75 - 0.22

Hmm... not what I expected! BuildASoil 3.0 looks to be too hot by a factor of: 38 - 219 - 7.3

Let's look at another one... Roots Organics "Lush" Organic Potting Mix... roughly in the pallpark with BuildASoil 3.0...

Roots Organics Lush: 1.00 - 0.50 - 0.50

So by now you might be asking, what the heck is going on here?!

NOW let's add another level of complexity, and that is, the recognized best NPK for growing cannabis appears to be 3.00 - 1.00 - 1.00 (for veg). CAVEAT: This does not necessarily mean you create or acquire a grow mix that has NPK 3 - 1 - 1.

So, what we are seeing with these commercial soil mixes is that they contain a starting amount of nutrients that will last for a while, and then the grower will need to add nutrients. Or the grower will need to add nutrients basically immediately.

Now let's compare SOHUM to the ideal, 3 - 1 - 1 (for veg):

SOHUM: 0.50 - 0.50 - 0.25
IDEAL: 3.00 - 1.00 - 1.00

From this, we see SOHUM isn't hot at all... it's the opposite. SOHUM is deficient from the ideal by a factor of: 6 - 2 - 4. In other words, SOHUM has 1/6th the N, 1/2 the P, and 1/4th the K, than it should have to support optimum cannabis growth. (Can also be written, 16.6% N, 50% P, 25% K.) These deficiencies need to be remedied by adding liquid form NPK in the water.

From this, we see that basically all commercial potting soils are going to require added NPK (macro nutrients), and probably also micro nutrients (Ca, Mg, etc).

To conclude, here are the "deficiency factors" for the above mentioned soils*, as a percent of the ideal 3 - 1 - 1 (higher percent means more nutrients):
HAPPY FROG ......... 0.30 - 0.30 - 0.05 -> 10.0% - 30.0% - 05.0%
STONINGTON ......... 0.50 - 0.34 - 0.12 -> 16.6% - 34.0% - 12.0%
SOHUM .............. 0.50 - 0.50 - 0.25 -> 16.6% - 50.0% - 25.0%
BUILD-A-SOIL 3.0 ... 0.95 - 1.75 - 0.22 -> 32.7% - 175.% - 22.0%
ROOTS ORGANICS ..... 1.00 - 0.50 - 0.50 -> 33.3% - 50.0% - 50.0%

* I was going to include PRO-MIX soil as well, but it apparently has no added nutrients. EDIT: Coast of Maine's Stonington soil added 8/11/22.

To bring this home to my own grow, I use my own custom-made organic living soil, with added organic fertilizers for macro and micro nutrients, at quantities that I control and experiment with. I also water with a high-N liquid fert with NPK 11-2-4, which also contains Na, Cl, Mg, and Ca. (Note, the Na and Cl are not in the form of sodium chloride, i.e. "salt," but are free-floating ions.)

My analysis of all this is... if you can build your own soil, then you can give it NPK values close to the ideal, and then add liquid fert only enough to maintain those levels. When going into flower, more P & K can be given, and less N (1-3-3 instead of 3-1-1). This is the ideal for a true soil grow, as opposed to a coco-type grow which is closer to hydroponic.

My next step is to determine the NPK of my soil mix, by having it tested at a lab.

Happy growing!
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
Someone once told me that Coast of Maine's Stonington Blend soil was pretty much "stick a plant in it, add water, and (eventually) harvest the plant" stuff if you had ten or fifteen (US) gallons of the stuff in your container. I wonder how its numbers compare to the above.
 

cbdhemp808

Well-Known Member
Someone once told me that Coast of Maine's Stonington Blend soil was pretty much "stick a plant in it, add water, and (eventually) harvest the plant" stuff if you had ten or fifteen (US) gallons of the stuff in your container. I wonder how its numbers compare to the above.
I did a quick check... the Stonington mix appears to be like all the others... you have to add nutrients. The back of the bag has no NPK or guaranteed analysis... it's conspicuously absent. (Not absent in FF Happy Frog and Ocean Forest.) I'd be surprised if its NPK compares to the BuildASoil 3.0 or the Roots Organics.

Yet, Coast of Maine makes this bold advertising claim,

Coast of Maine’s Stonington Blend is a pre-mixed “super soil” that contains EVERYTHING your cannabis plants need for a full grow cycle. YOU ONLY NEED TO ADD WATER!

I call B.S. because at the bottom of the web page, they are advertising their fertilizer and feeding schedule...

 

cbdhemp808

Well-Known Member
For folks who don't want to make soil from scratch, but want the soil to contain the right NPK for growing cannabis, you could start with, for example, Fox Farm Happy Frog, or Ocean Forest if you can't get the Happy Frog. You can consider this your "base" potting soil. It will need fertilizer added to it, to bring it up to the optimum 3-1-1 NPK for growing in veg.

I really like the Down to Earth fertilizers (DTE), because they're organic, it's a good company, and they are available at a lot of grow shops and garden supply stores. They are also available directly from the Down to Earth retail store's website (Eugene, OR). They carry various "single ingredient" ferts, as well as "solution grade" powders that can be mixed with water, and also liquid ferts. You can buy small quantity boxes – 2 lb, 5 lb – ideal for small grows, or you can buy large quantity in bags. They also sell a potting soil, and a PRO potting soil that contains myco and bacteria (similar to Happy Frog).

I recommend these DTE ferts* to blend in with your bagged potting soil, in the right amounts:
  • bat guano (N)
  • seabird guano (Ca, P)
  • dolomite lime (Ca, Mg)
  • oyster shell powder (Ca)
  • greensand (K, Fe, Si)
  • gypsum (Ca, S)
  • potassium sulfate (K, S)
* These all check out for very low heavy metals content.

How much of these you add is up to you, but you can more or less follow the instructions on the bag or box – see "Application Rates" for containers. For example, for greensand they say "add 1-2 tbsp per gallon of soil".

Both Happy Frog and Ocean Forest are peat moss based – they don't contain coco coir. The DTE potting soils do contain coco coir. If your base potting soil doesn't contain coir, I highly recommend adding some.

At this point, you've got a well-fertilized organic soil mix, and you can test the pH and make adjustments as needed.

You can then add liquid ferts, or solution-grade ferts, when you water, to keep the nutrient levels up to optimum. During veg you want more N, and during flower you want less N and more P and K. The optimum soil NPK for flowering is 1-3-3. This means it makes sense to add N, P, and K, when you water – in different amounts depending if the plant(s) are in veg or flower.
 

cbdhemp808

Well-Known Member
Here's the NPK of Fox Farm Happy Frog and Ocean Forest

Almost exactly the same... Ocean Forest has a slight bit more P. Happy Frog also contains humic acid, myco, and bacteria. Ocean Forest doesn't contain these. Both products are peat moss based and contain no coco coir.

1659835309425.png


1659834935295.png
 

SmokingWings

Well-Known Member
Here's the NPK of Fox Farm Happy Frog and Ocean Forest

Almost exactly the same... Ocean Forest has a slight bit more P. Happy Frog also contains humic acid, myco, and bacteria. Ocean Forest doesn't contain these. Both products are peat moss based and contain no coco coir.

1659835309425.png


1659834935295.png
This pretty much blows right out of the water the theory that the Happy Frog is a milder & not-as-hot soil as the Ocean Forest and better suited for delicate seedlings or cuttings just starting to root. They both have the same amount of Nitrogen but 10% of the Happy Frog's nitro is ready to be absorbed by the roots while the Nitrogen in the Ocean Forest will need more time by the micro-organisms before it is ready for the plant.
 

Emilya Green

Product Reviewer
420 Staff
You are all forgetting something here. The NPK readings are simply a snapshot in time as to how the soil looks when you first install it. Ocean Forest has additional organics in its mix, that over time break down to provide more NPK. The richness of this soil with all of its ocean and forest bits can not be denied. The initial numbers don't tell the complete story. Happy Frog is designed to grow roots. Ocean Forest is designed to provide long term nutrition through the life of the grow due to the slow breakdown of the organics over time. Two different soils, two different purposes.
 

SmokingWings

Well-Known Member
You are all forgetting something here. The NPK readings are simply a snapshot in time as to how the soil looks when you first install it.
When the recommendation is made to use the Happy Frog for starting seedlings or cuttings then there is little difference between it and the Ocean Forest. And, the recommendation to the use the Frog is because it it milder. Weeks later when the seedling or the rooted cutting has grown into a young plant we will see that the Ocean Forest soil is providing more of what the plant or clone needs while the Happy Frog has run out of steam.

Why not just mix some humic acid, mycos, and bacteria into the Forest stuff and start there? Since there is not enough water soluble Nitrogen to rate a mention on the label it would also be "not hot" for the several weeks while the roots get started. We still get the long term release of nutrients. And, for the "Auto-flower" growers it could mean one fewer transplanting which some of they say can cause a stunted plant.

I am all for the richness of the Ocean Forest soil, or any soil, with all of those decomposing forest bits and pieces. Just for 'bits and giggles' I am making my own version of Aged Forest Products.
 

cbdhemp808

Well-Known Member
You are all forgetting something here. The NPK readings are simply a snapshot in time as to how the soil looks when you first install it. Ocean Forest has additional organics in its mix, that over time break down to provide more NPK. The richness of this soil with all of its ocean and forest bits can not be denied. The initial numbers don't tell the complete story. Happy Frog is designed to grow roots. Ocean Forest is designed to provide long term nutrition through the life of the grow due to the slow breakdown of the organics over time. Two different soils, two different purposes.
I think more the opposite – the Frog has added humic acid, myco, and bacteria, so would be better at "breaking down" what's there and making it more available over time.

Does Fox Farm even make any claims about the microbe content of Ocean Forest? I mean, they are obviously sterilizing both products. The Frog has microbes added after sterilization. What about enzymes? Are enzymes being destroyed in the sterilizing process? I think so, because 118°F destroys enzymes in food. Sterilizing temp is probably at least 212°F, because that's the temp to kill bacteria. For fungi, it's 140-160°F.

To conclude, here are the "deficiency factors" for the above mentioned soils*, as a percent of the ideal 3 - 1 - 1 (higher percent means more nutrients):

HAPPY FROG ......... 0.30 - 0.30 - 0.05 -> 10.0% - 30.0% - 05.0%
I think the main point is that both FF products are a long way from the ideal NPK 3-1-1 for cannabis, and no further decomposition is going to substantially change that. For example, total N is there in the product from the beginning – it isn't created during decomposition. That's my understanding. Microbes can help make the NPK more available.

So, for Happy Frog, it only has 10% of the N, 30% of the P, and 5% of the K. The numbers for Ocean Forest are similar.

As for starting seedlings in small pots (e.g. 2" or solo cups) – if indeed either FF product is considered "too hot," which doesn't make a lot of sense to me – one could simply use some coir in the mix, e.g. 50/50.
 

cbdhemp808

Well-Known Member
Regarding humic acid, from DrEarth.com:

...[chelates] positively charged multivalent ions (Mg, Ca, Fe and other “trace minerals” of value to plants)...​
facilitates the uptake of the [mineral ions] by means of several mechanisms, one of which is preventing their precipitation (leaching through the soil). Another is the direct and positive influence on [mineral] bio-availability...​

...increases nutrient uptake, drought tolerance, and seed germination. It increases the microbial activity in the soil, making it an excellent root stimulator. Humic acid increases the availability of nutrients in our fertilizers and in those already existing in your soil. It will help to aerate the soil from the inside....​
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
I call B.S. because at the bottom of the web page, they are advertising their fertilizer

To be fair, lots of people don't want to use 15 gallons of soil per plant. I don't. I'll grudgingly fill a five-gallon bucket, if I must, but I'd rather go with a three-gallon container.

That's if I'm using soil, of course. I might use a two-liter pop bottle if gardening via a hydroponic method. (But I might use a Solo cup jammed into a hole I cut in the lid of a 23-gallon plastic tote full of nutrient solution, too.)

Not every strain has the exact same nutritional requirements. Or flowering periods length. And people keep them in the growth phase for different lengths of time. Environmental conditions affect growth rates. Something that a heavy-feeding indica would thrive in might burn and stunt an Ethiopian landrace sativa. While the notion of a complete, just add water soil initially seemed appealing to me... I remembered that it's easier to add a thing than to remove it. Plus, they seem to mostly have "organic" stuff in them, lol.
 

cbdhemp808

Well-Known Member
I don't get it... how does your reply relate to what I said, "I call B.S. because at the bottom of the web page, they are advertising their fertilizer" ?

To be fair, lots of people don't want to use 15 gallons of soil per plant. I don't. I'll grudgingly fill a five-gallon bucket, if I must, but I'd rather go with a three-gallon container.
why are you mentioning 15 gal here?

Not every strain has the exact same nutritional requirements. Or flowering periods length. And people keep them in the growth phase for different lengths of time. Environmental conditions affect growth rates. Something that a heavy-feeding indica would thrive in might burn and stunt an Ethiopian landrace sativa. While the notion of a complete, just add water soil initially seemed appealing to me... I remembered that it's easier to add a thing than to remove it. Plus, they seem to mostly have "organic" stuff in them, lol.
How does this relate to Stonington mix?
 

SmokingWings

Well-Known Member
I think the main point is that both FF products are a long way from the ideal NPK 3-1-1 for cannabis, and no further decomposition is going to substantially change that. For example, total N is there in the product from the beginning – it isn't created during decomposition. That's my understanding. Microbes can help make the NPK more available.
There is one other point that has to be considered. While the continued decomposition of the organic material will not raise the percentages of the macro-nutrients enough to make a difference in the percentages available it is a continuous process. The nutrients are available to the plant the entire time.

Unlike the hydroponic or non- mineral soil mediums where the nutrients have to be added on a regular basis whether once a day or once a week.

... a long way from the ideal NPK 3-1-1 for cannabis, and no further decomposition is going to substantially change that.
We can still grow a plant from seed till harvest in the soil. The harvest will not have the quantity or quality most of us are looking for but it can be done.

So we add some Potassium and get a slightly healthier plant. The plant gets a bit larger and we see that adding some Nitrogen produces healthier leaves and the plant grows better. We keep adding this and that and have a larger harvest than anticipated. But, the plant will grow properly with the 3-1-1 but we never seem satisfied so we make plans on adding this and that and the bigger and better the plant the more we have to add just to maintain.

Then we want more than just maintaining so we add some more, we get more but in the long run the plant would have been able to produce enough to perpetuate the specie with the 3-1-1 as long as we provided enough water the entire time.
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
I don't get it... how does your reply relate to what I said, "I call B.S. because at the bottom of the web page, they are advertising their fertilizer" ?


why are you mentioning 15 gal here?

Because the company states that I may be able to grow a cannabis plant from seed to harvest in a 15-gallon container full of their soil - but I might (do, actually) prefer to grow one in a much smaller container... yet still harvest a fair bit of bud. Therefore, it would be logical to assume that I would benefit from being able to add nutrients at some point.

How does this relate to Stonington mix?

It relates to all of them. Cannabis plants are not generic, and neither are their nutritional requirements. One that flowers for 16 - or more - weeks might require more nutrients than one which flowers for eight to ten. Or it might not. It might also require a slightly different ratio of macro/micronutrients.

If I only want to grow one plant, but still want to fill my garden, I'm going to have a long growth phase. And, again, I'm not going to want to have a (relatively) massive container of soil.

If I decide, next year, to stick an autoflowering plant in the woods - and am not too decrepit to carry in a lot of soil, but don't want to go back to do anything but water it if/when there's a period of no weekly rainfall, I have the option of doing so.

If a company that sells a soil can also provide me with one or more supplemental nutrient products, that's a good thing. Different people, different methods, different strains, different container sizes... Some combinations are going to require additional nutrients at some point - and some will not. I am not going to penalize a company for not anticipating my specific needs (each and every time) and then changing things so that I never have reason to add anything (other than water). That just doesn't seem realistic.
 

cbdhemp808

Well-Known Member
Because the company states that I may be able to grow a cannabis plant from seed to harvest in a 15-gallon container full of their soil - but I might (do, actually) prefer to grow one in a much smaller container... yet still harvest a fair bit of bud. Therefore, it would be logical to assume that I would benefit from being able to add nutrients at some point.
The company states,

Coast of Maine’s Stonington Blend is a pre-mixed “super soil” that contains EVERYTHING your cannabis plants need for a full grow cycle. YOU ONLY NEED TO ADD WATER!

They don't mention a pot size... until you scroll down.

[ADDED]
Here's the web page in question:

For 5 gal I think they say it will feed for 30 days.

[CORRECTED]
As with the other commercial potting soils, you are going to need to add nutrients, and the timing depends on pot size, what your are growing, and other factors.

In my analysis (^TOP) you can see that there's a lot of variation in NPK among the commercial potting soils. Companies that don't list NPK, well... there's only one reason for that. Keep in mind that I'm coming from the point of view of someone who crafts their own soil, so I have no assumptions about commercial potting mixes and their associated (liquid) ferts.

It relates to all of them. Cannabis plants are not generic, and neither are their nutritional requirements. One that flowers for 16 - or more - weeks might require more nutrients than one which flowers for eight to ten. Or it might not. It might also require a slightly different ratio of macro/micronutrients.

If I only want to grow one plant, but still want to fill my garden, I'm going to have a long growth phase. And, again, I'm not going to want to have a (relatively) massive container of soil.

If I decide, next year, to stick an autoflowering plant in the woods - and am not too decrepit to carry in a lot of soil, but don't want to go back to do anything but water it if/when there's a period of no weekly rainfall, I have the option of doing so.

If a company that sells a soil can also provide me with one or more supplemental nutrient products, that's a good thing. Different people, different methods, different strains, different container sizes... Some combinations are going to require additional nutrients at some point - and some will not. I am not going to penalize a company for not anticipating my specific needs (each and every time) and then changing things so that I never have reason to add anything (other than water). That just doesn't seem realistic.
I agree; however, I'm just calling out this particular company for false advertising.

I'm all for adding ferts, but I like to minimize that by incorporating plenty of ferts in the original mix. I'm still doing some tuning though... pot sizes, amount of ferts in the original mix, type and amounts of watered-in ferts.
 

NAGreengo

Well-Known Member
There are so many factors other than NPK content in 'living soils' such as:
Microbes, and types. Does it contain Mycorrizae? What are the nutrient sources? And finally.. Bioavailabilty.

When some growers refer to a soil being 'hot'. It can be easily misconstrued that what they are referring to is the listed NPK values..which by the way are almost useless numbers when discussing organic living soils.


:peace:
 

cbdhemp808

Well-Known Member
There are so many factors other than NPK content in 'living soils' such as:
Microbes, and types. Does it contain Mycorrizae? What are the nutrient sources? And finally.. Bioavailabilty.
Yes, we are talking about commercial potting soil. Some contain microbes, for example Fox Farm Happy Frog does, while Fox Farm Ocean Forest doesn't.

When some growers refer to a soil being 'hot'. It can be easily misconstrued that what they are referring to is the listed NPK values..which by the way are almost useless numbers when discussing organic living soils.
What would "hot" mean to you? It almost universally means high nitrogen, but I think also refers to high P or K.

I disagree that listed NPK are almost useless. What's useless is making assumption about what nutrients are contained in any given commercial potting soil, without really knowing. My analysis shows that some of the potting soils have a lot more nutrients than others.

"One of the most popular potting soils (with lots of plant food included) is FoxFarm Ocean Forest soil."

Actually, Ocean Forest and Happy Frog have about the same amounts of included ferts, but HF contains humic acid and microbes, while OF doesn't. The amount of nutrients in either of these is low on the scale compared to other potting soils, and far from the ideal NPK of 3-1-1. The conclusion is that all commercial potting soils will require added ferts...

My analysis is at the top of this thread
^TOP
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
They don't mention a pot size... unless maybe if you scroll down.

It's near the top of the product's web page:

Coast of Maine said:
Stonington Blend Grower’s Mix is a complex “super soil” designed for high performance container growing. It works well with tomatoes, and, where growing cannabis and medical marijuana is legal, growers have reported tremendous results. This soil incorporates mycorrhizal fungi, kelp, fish bone and alfalfa meal, as well as worm castings, peat, coir and lobster compost. When growing in 15-gallon containers, there is no need for additional nutrients.

Target pH: 6.3

Again, they avoid mentioning anything about NPK or guaranteed analysis on their bag and on their website

Except where they mention it on the bag. And on their website.:

Coast of Maine said:
The Coast of Maine Difference

Here at Coast of Maine we are proud of the quality and consistency of our compost-based soils. Compost (naturally decomposed organic matter), we believe, is the key ingredient. Ours are made using carefully designed and tested recipes which include the very best ingredients (sustainably sourced from pristine ocean waters and local farms) combined with rigorous quality controls. We never use biosolids, municipal or household waste. Close attention to detail with frequent turning, sampling and testing, plus a lengthy aging and curing process, produces dark, rich compost that builds soil and enhances plant growth.

Stonington Blend™ Organic & Natural Grower’s Mix is the ideal soil for high-performance, organically raised crops, whether field or container grown. It is carefully formulated to provide balance between structure, water retention, drainage and aeration for growing strong, vigorous plants. It provides the rich and diverse soil your plants need.

We use all natural ingredients

Stonington Blend is 40% sphagnum peat moss, coco fiber (coir), composted manure, perlite, fertilizer (see below) and mycorrhizae.

COAST OF MAINE® STONINGTON BLEND™
ORGANIC & NATURAL GROWER’S MIX
0.50 – 0.34 – 0.12
GUARANTEED ANALYSIS
Total Nitrogen (N) …………………………………………… 0.50%
0.50% Water Insoluble Nitrogen*
Available Phosphate (P2O5) ………………………….. 0.34%
Soluble Potash (K2O) ……………………………………… 0.12%

Derived from: Composted poultry manure, fish bone meal, lobster & crab shell, kelp meal, earthworm castings and alfalfa meal.

*0.5% Slowly available nitrogen from composted poultry manure,
fish bone meal, lobster & crab shell, kelp meal, earthworm castings
and alfalfa meal.

ALSO CONTAINS NON-PLANT FOOD INGREDIENTS:
Soil Amending Ingredient Guaranteed Analysis
Active Ingredients
Endomycorrhizae species
Glomus intraradices………………………………………… 0.07 spores/gram
Total Other Ingredients…………………………………… 99.9%

Stonington Blend is carefully formulated from natural ingredients to provide an ideal balance between water retention, soil texture, drainage and aeration in a consistent growing medium.

This unique container mix is named after the historic fishing village of Stonington, located on the south shore of Deer Isle in East Penobscot Bay. Settled in the 1760’s, Stonington is today Maine’s largest commercial fishing port and once home to an important granite quarrying industry.

Stonington Blend contains viable mycorrhizal propagules per cubic centimeter (cc) of the following organism:

Endo Mycorrhizae species:
Glomus intraradices @ 00.07 spores/cc


Endomycorrhizal fungi colonize approximately 80% of the world’s plant species, including most vegetables, fruit trees and shrubs, flowering plants, grasses, legumes and many more. For more information about mycorrhizae visit:
Code:
https://www.usemyke.com

There's more, but it's basic information (how to store soil, don't place mutually antagonistic plants in the same container, how to transplant, how to water, "purple ink drawings" accompanying the basic information, pictures of the bag, links to the product's SDS and OMRI certification, store locator, online shopping).
 

NAGreengo

Well-Known Member
Yes, we are talking about commercial potting soil. Some contain microbes, for example Fox Farm Happy Frog does, while Fox Farm Ocean Forest doesn't. I did an analysis of various potting soils here.


What would "hot" mean to you? It almost universally means high nitrogen, but I think also refers to high P or K.

I disagree that listed NPK are almost useless. What's useless is making assumption about what nutrients are contained in any given commercial potting soil, without really knowing. My analysis shows that some of the potting soils have a lot more nutrients than others.


"One of the most popular potting soils (with lots of plant food included) is FoxFarm Ocean Forest soil."

Actually, Ocean Forest and Happy Frog have about the same amounts of included ferts, but HF contains humic acid and microbes, while OF doesn't. The amount of nutrients in either of these is low on the scale compared to other potting soils, and far from the ideal NPK of 3-1-1. The conclusion is that all commercial potting soils will require added ferts...

Analysis of commercial potting soils
The listed NPK in living soil requires Microbes to maintain them, and to actually make them available to your plants. If environmental factors go afoul then the balance will be disrupted.

A hot soil can mean one of two things to me.

1. A non living soil contains far to much N, P, or K, causing lockouts or Nute burn.

2. A living soil has cooked before cultivation and nutrients have become volatile.
 

cbdhemp808

Well-Known Member
It's near the top of the product's web page:
Here's the page that makes the false claim, near the top:

Coast of Maine’s Stonington Blend is a pre-mixed “super soil” that contains EVERYTHING your cannabis plants need for a full grow cycle. YOU ONLY NEED TO ADD WATER!


Except where they mention it on the bag. And on their website.:
OK, I missed that... you have to scroll to the bottom of the product page. They don't show the back of bag in the product photos. I did look for a back-of-bag image on the web... didn't find one until tonight.

Thanks, I will edit my reply above.
 
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