I’ve grown chilis and cannabis without really knowing what I am doing, now I wanted to learn to grow any veggies, but finally learn about soil and prepare it well myself.
I naively tried to use coco substrate with tap water and killed off my tomato seedlings pretty fast. Then I’ve did some research into soil and learned about more organic approaches, and also that pure coco is a bit like dry hydroponics and needs a lot of understanding, and that I probably both over-fertilized and starved them at the same time.
I’m going to start from seeds in Mel’s mix with 1/3 coco 1/3 perlite/vernaculite 1/3 compost. Is this kind of substrate to be treated as organic or as mineral approach? The compost probably adds the typical soil properties including the buffering of pH and EC and taking care of fertilization.
But I do not want to re-pot all the time, it is messy and inconvenient. I don’t really like working with soil. Instead I want to use mineral fertilizers. Once the compost is depleted, can I consider it to be like a non-soil grow? I got a pH/EC sensor to check my water and the drain coming out, diluted a pH- down based on diluted citric acid to normalize my water to 6,5pH, which seems like a good starting point for any situation.
Does it make sense to follow some generic approach (like keeping pH/EC in certain ranges in certain growth stages)? I do not want to use commercial fertilization formula schemes. I want to work with standard off the shelf mineral fertilizers. Is it possible to get decent results with that?
And where can I find that kind of information for general vegetables, like tomatoes or cucumbers etc.?
The whole soil business is pretty overwhelming, but I want to learn enough (without getting a degree in agriculture) so that I can do this not blindly but improvise with available substrates and fertilizer. How to get this knowledge?
“Growing concepts” are simplified methodologies that offer a recipe for those who don’t understand the complexities.
Professionally I advise commercial growers on their farms, greenhouses, etc… so not a beginner. I understand all the little bits and pieces so I can cut through all the bullshit and combine all the fundamental concepts.
I can give you some basics to help you understand my recommendations.
Water holding capacity = particle surface area. In soil, clay has the highest water holding capacity. Coir is a ton of little fibers that hold water in your mix. It needs to be somewhat compacted to work well however.
Plant nutrition - at the molecular level plants can only take up certain forms of nutrients. To the plant fertilizer from compost or a hydroponic blend is the same thing. They are molecularly identical.
Organic matter - this refers to mostly broken down organic material. Microbial activity reduces to a slow steady rate. Compost is organic matter.
Cation Exchange Capacity - this refers to mineral clay or organic matters ability to loosely bind to positively charged nutrients. This keeps them available for plants to use.
Porosity/drainage - these are channels for air/water to move in the soil matrix. Larger particles like sand/perlite/vermiculite are a source of these. Aggregate formation by microbial activity also create these.
“understand all the bits and pieces so I can cut through all the bullshit” -> that’s exactly what I was hoping to do.
Do you have some reading recommendation? You know, like in every area there’s this one book or two you’d give a beginner to learn the most important things right from the start, and the rest is details you can fill in and refine later ? In another comment I got some book recommendations, don’t know what you think about them.
Contrary to a different commenter, who advised not to mix soil and non-soil, you seem not to have any issues with fertilizing with mineral NPK fertilizer on soil?
I also did that before without second thought, but I got warned that it kind of leaves the microbes in the soil/compost starving or something. I guess that would matter only if you try to do “living soil” or something, and otherwise the worst thing that happens is the microbial life in the soil dies off and I just have depleted substrate (with possibly molecules holding NPK in locked form that cannot be released without the microbes) that I can fertilize with mineral fertilizer without any issue, is this correct ?
And thanks for replying :)
Reading recommendations: The problem is it’s not one topic or even one field. You need to read the basics in Chemistry, Biochemistry, Hydrology, Physics, Microbiology, Genetics, Agronomy, Plant Physiology, Plant Pathology, etc… This is the the reason that there is so much bullshit floating out there.
Referring to bullshit, the poster you referenced is an excellent example.
Microbial activity in soil is dependent on the combination of organic matter, the balance of nutrients, gas exchange, temperature and water. There is no such thing as no microbial activity in the soil (dead soil). There is lower activity and higher activity. Why do we care? Higher microbial activity is linked to greater nutrient availability for uptake by plants.
The main food source for microbes in the soil is organic matter. When you add in mineral fertilizers it initially increases microbial activity on the soil. The balance of nutrients allows the microbes to eat the organic matter quicker. Eventually the organic matter becomes depleted and microbial activity decreases. Less food = less activity and less available nutrients for plants. Adding in compost or other organic matter spikes back up microbial activity.
Instead of understanding the entire process, most people have a simplistic view of compost = higher microbial acrivity and mineral fertilizers = decreased microbial activity. You see it in blogs, gardening guides etc all over the place. It fits nicely into their “organic” = good, “conventional” = bad. They all miss the little fact that the highest microbial activity is a combination of organic matter and mineral fertilizer. Reality doesn’t fit into their preconceived ideas.
Maybe you have an answer to what non-professionals can’t really help with, I tried to ask it here in the thread and got no satisfactory reply so far.
Let’s say I have some substrate, let’s assume I got drainage, oxygen etc. all dialed in a good range. And let’s assume that I would like to work more with “conventional” mineral fertilizers mostly.
Is there reliable information about how much and when and how often to fertilize some plant and with which nutrients? Because that seems to be the most difficult thing to get right and learn.
Is it really that vendor-dependent? I would guess the fertilizer “formulas” are another marketing scam to convince people to stay with a brand they are used to, and if you know what you are doing you could combine mineral fertilizers of arbitrary brands and figure out the right dosage for some specific plant at a specific point of its life.
If this is really not as simple (because there’s more to fertilization than NPK and pH, I get it), then fertilizer bottles are ultimately as much of a black box as the diverse microbes in working in the soil.
But I was hoping with mineral fertilizers you can really know what is going on and why, and that this must be something learnable without getting a degree in biochemistry and without just paint-by-numbers vendor specific instructions.
Like, I know there are the tables of ranges of nutrient uptake dependent on pH, which gives rise to the “slightly acidic substrate with pH 5-6” guideline.
Now I wish there was like a table showing for different plant per development stage how much of what it needs and maybe some info on how to calculate fertilization based on a random bottle I have, maybe mixing it with some other stuff, if the balance is too far off either by calculation or I see that the plant is missing something.
Or like, I know light green leaves in new growth are likely a nitrogen deficit. Are there some universal cues you can use to diagnose a plant? I guess this is where deeper plant physiology and pathology knowledge is probably needed…
Whatever the marketers claim there is only one part of the label that matters: The guaranteed analysis. It doesn’t matter what they label it for, it’s all the same stuff in different formulations. Once you understand the formulations you absolutely can mix and match to find the best fit. The convention of how to label fertilizer can be country or region specific so you’ll need to do some research for your locality.
https://en.wikipedia.org/wiki/Labeling_of_fertilizer
All crops have recommended fertilizer amounts published. They are usually by the acre/hectare and the with the exceptions of legumes, the ratios are very similar. Only the amount of fertilizer they need varies. Legumes with proper nodulation need less N. Of course finding a good one that shows everything you need is a little difficult. They generally just show the total amount needed for the crop. Not the stages. Here’s an example for New York.
http://nmsp.cals.cornell.edu/publications/files/VegetableGuidelines2019.pdf
FYI Light green leaves on new growth = immobile nutrient deficiency (Fe, Zn, Ca, S, B, or Mn). Light green or yellowing leaves on the oldest leaves is mobile nutrient deficiency like nitrogen.
https://www.canr.msu.edu/news/knowing_nutrient_mobility_is_helpful_in_diagnosing_plant_nutrient_deficienc
BTW: Since you are using pots with coir & compost, pH is not really an issue. They have a large buffering ability and will keep the pot in the ideal 6.2-6.8 pH range naturally.
Great, thanks a lot! Before possibly wasting time trying something unrealistic, I just wanted some affirmation by someone with experience that this is in fact feasible with a bit more research!
Also good to know that compost acts as a pH buffer, I’ve read that there are special buffering solutions to apply to coco coir, but if I go the compost-enriched route it’s one less variable to control and manage.