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Question: best way to learn about soil, fertilization and growing in coco or other non-soil substrates? (feddit.org)
submitted 1 year ago* (last edited 1 year ago) by zenforyen@feddit.org to c/gardening@lemmy.world
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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?

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[–] Redfox8@mander.xyz 0 points 1 year ago (1 children)

My experience of veggies is they are mostly very tollerant of moderate soil conditions (i.e. no extremes). No need to go heavy on perfecting the soil, so long as it's decently fertlised you'll get s decent crop :). Most are cultivated with ease of growth in mind. The one thing I'd say is to not plant in pure compost in pots or raised beds as it dries out too quickly (your coco coir experience sounds like that was a major factor). An enriched soil will do just fine.

For seed sowing, the main thing is that it isn't too rich otherwise they'll grow too leggy too quickly. You pot on or plant out once the 'baby' leaves are outgrown typically once the energy from the seed is spent. Other than that don't fuss. I've tried perlite and vermiculite and didn't find it made the slightest bit of difference. It just makes a nicer soil in terms of being fine and workable. Buy a seed compost if you really want something good. I use any junk I have available frankly! So long as it's not too lumpy! A soil that doesn't swing from dry to wet is probably most important at the germination stage. You can cover pots with cling film to help that, especially whilst on a heat mat.

If you suspect your outdoor soil may be strongly acid or alkaline, get some test strips snd check and pull it closer to pH7-7.5. Otherwise just plant out.

You'll find there's always a few things that either really don't like your garden/growing space, for no apparent reason!

Re guides : the RHS has tonnes of info. Also take a rummage in a thrift/charity shop, or go to your library - growing methods don't go out of date! But you can also follow the guides on the seed packets and you'll do ok! Albeit with a few failures ;) life isn't perfect and your plant growing won't be either, just aim to enjoy whatever crop you get :)

[–] zenforyen@feddit.org 0 points 1 year ago* (last edited 1 year ago) (2 children)

The most "outdoor" I have is the balcony, so it will be a pot- and box-based little garden (some that will be permanently outside and some more movable).

Thanks for the tips! Good point, I also maybe should not overthink or over-engineer it. I'm a software engineer so maybe I approach this way too analytical :D

[–] The_v@lemmy.world 0 points 1 year ago (1 children)

In plant science and agriculture there is a shit ton of variables. The majority of them are unknown and/or constantly changing You can only create general approximations to cover the plants basic needs and hope for the best.

Water storage. Coir does a good job at this as long as it has been treated with the proper surfactant (wetting agent). Untreated coir is hydrophobic and a complete clusterfuck.

Gas exchange with the roots: Coir alone tends to hold too much water and blocks adequate air motion. I always blend in 40% sand with it to improve drainage and gas exchange. It also adds in some weight and keeps the pots from falling over in the wind.

Cation Exchange Capacity - this is the storage battery in soil for positively charged nutrients. Mineral Clay, Compost, Peat etc are all very high in these. Around 5% compost by weight is usually enough.

I usually blend in some 6 month slow release (polymer coated) fertilizer in my pots at the beginning of the season. I almost never have to add in more during the growing season. This needs to have a NPK ratio of around 3-1-2 plus a micronutrient blend.

I reuse the soil in the pots every year. Add 2-3% more compost to replace the lost organic matter and blend in some more fertilizer.

[–] zenforyen@feddit.org 0 points 1 year ago* (last edited 1 year ago) (1 children)

Good to know about reusing soil, I always thought it's wasteful and inconvenient to throw it away and in an actual garden nobody would do that. So I am also definitely going to try reusing soil I use in the pots, just bought a sieve to simplify the process of removing roots etc. from used soil.

Only 5% compost ? I don't know how dense compost is, but typical suggested DIY mixes use more like 1/4-1/2 compost, by volume.

I was planning to do 1/3 coir for the loose structure, 1/3 of some perlite or similar, to hold water better, and 1/3 compost for initial nutrients, and then see how it behaves and adjust.

Would you recommend to use other proportions? I was going to experiment with the perlite percentage and see how it behaves with respect to watering etc. But with compost I really don't know how I would even estimate how much I need to add so that a plant has enough "food" from seedling up to the first weeks of growth.

Would adding more compost to the mix simply extend the "nutrient store" for longer? I've read that you cannot so easily over-fertilize with compost / organic fertilizers, so I guess it's then more about price/availability?

Is it cheaper or simpler to have less compost and more of that (I guess solid) slow release fertilizer, is that why 5% is enough?

That does sound very convenient. If I could mix some soil with slow release fertilizer and it would last the whole season, that sounds pretty awesome. I guess it's released due to repeated watering? Or is it decomposing and releasing at its own pace? Like, do I have to worry about releasing too much if I water too much?

[–] The_v@lemmy.world 0 points 1 year ago (1 children)

The online guides assume that you want enough nutrients from the compost alone to feed the plant through the entire growing cycle. The actual nutrient analysis of compost varies radically based upon the source of the composted material. So they all assume the lowest testing stuff and overdo it.

If you are adding in compost as an organic matter "battery" to recharge with conventional fertilizer, 5% is plenty.

Go ahead and use vermiculite or perlite but you have to send me pictures after you water so I can laugh. It floats and makes a mess everywhere. It also makes the mix lighter and a little breeze will knock over the plants. If you want to reuse the soil, blend in a bit of sand. It stays put, adds weight, and does a better job. Commercial potting soil mixes use the lighter perlite/vermiculite to save on shipping costs.

Slow release fertilizers are coated with polymers that degrade at a steady rate based upon temperature and moisture. Leaching out nutrients with the water will occur but having a bit of organic matter to catch the positively charge ones helps immensely.

[–] zenforyen@feddit.org 0 points 1 year ago (1 children)

I thought compost is supposed to be microbiologically active and fertilization is produced and released by microbial activity, while mineral fertilizers are more typical for hydroponic setups and do not rely on any biological activity, why not buffer nutes directly in the coco? I thought they built up salts over time? Now I'm confused.

What kind of approach are your recommendations based on? It sounds like neither the typical information for soil growing nor like hydroponics, but you do include some organic material in your mix and still fertilize with mineral fertilizers?

Concerning the additives, I thought the point of vernaculite was that it's porous and was intended to actually keep the water longer, and for pure drainage you would use something else. I already noticed that coco coir also dries pretty quickly and wondered if with these additions it would behave more like soil in how long and how much water it can hold. You do not seem to be fond of them.

What do you recommend to read that explains your perspective? It seems not to fit in any "growing concept" I can recognize, so I'm curious.

[–] The_v@lemmy.world 0 points 1 year ago (1 children)

"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.

[–] zenforyen@feddit.org 0 points 1 year ago (1 children)

"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 :)

[–] The_v@lemmy.world 0 points 1 year ago (1 children)

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.

[–] zenforyen@feddit.org 0 points 1 year ago (1 children)

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...

[–] The_v@lemmy.world 0 points 1 year ago

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.

[–] Redfox8@mander.xyz 0 points 1 year ago

No problem! Look up "all you can eat in three square feet" there's a good book of that title, could be some online stuff too. Also read up about companion planting.

Soil science both in terms of chemistry and micro organisms can be quite interesting, but probably only of much use for troubleshooting. Although the nature of balcony/pot growing probably makes it less relevant as you'll be wanting to refresh the soil/compost each year so the conditions will be too changable to use that if you have problems. I'd focus on pest defence, light/heat, watering and fertilising (fresh compost will provide nutrients for a few months generally) over more specific soil conditions!

[–] just_another_person@lemmy.world 0 points 1 year ago (1 children)

Soil Science For Gardeners is great (especially for free).

Teaming With Microbes is another great one.

[–] zenforyen@feddit.org 0 points 1 year ago (1 children)

Oh great, thanks! I'll check them out. All the blog tutorials only scratch the surface (while copying from each other), but it is hard to find a suitable book that is reasonably comprehensive, written by someone who really understands the topic, but also approachable for someone without a lot of experience.

[–] The_v@lemmy.world 0 points 1 year ago (1 children)

You'd probably have better luck reading some college textbooks on the subject. Plant physiology, Soil Science, Soil Microbiology, and Agronomy textbooks would give you a more rounded understanding on the subject.

[–] zenforyen@feddit.org 0 points 1 year ago

Thanks for suggesting the right search terms.

I almost expected that someone would say that.

I often end up reading university level stuff when researching a topic, but in areas that are far from my own academic background it's pretty painful to try and piece together the kind of semi-rigorous understanding I'm looking for.

Wish there was more material available on that level of "studied some other STEM field, but did not and will not study this field so lacks a lot of details taken for granted in that area, yet wants to learn more depth than pop-sci and dummy tutorials provide" for various disciplines.

[–] Guenther_Amanita@slrpnk.net 0 points 1 year ago* (last edited 1 year ago) (1 children)

Feel free to also join !gruenerdaumen@feddit.org if you want to see German content or !hydroponics@slrpnk.net for hydro stuff :)

I can answer you pretty much any question you asked in detail, but I have to keep it more brief, because answering everything extrensively would take hours. Just ask if you are interested in something and want to know more.

pure coco is a bit like dry hydroponics

There is no dry hydroponics. Hydro doesn't mean something has to sit in water, just that it doesn't eat decaying matter (soil).

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.

The other ingredients in there besides compost mostly add structure and prevent waterlogging.

Mentioning EC in soil doesn't make much sense, and dissolved salts don't get buffered much afaik, how should they?

Once the compost is depleted, can I consider it to be like a non-soil grow?

Nope, just organic, but now with depleted soil :D
You can add organic fertilizer, which is basically "ultra compact compost" if you see it like that.

I wouldn't add mineral fertiliser into organic soil, because it will heavily disrupt the soil life.

I got a pH/EC sensor to check my water and the drain coming out

Soil ≠ Hydro. Measuring something in soil doesn't work that easily than in hydro, and you can't change that stuff anyway, at least not that fast and easily.

I've had pH values of 8 in soil and still the plants looked fine. I believe the mycorrhizal networks can change nutrient uptake.
The pH in soil is often controlled by the microorganisms living there.

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.

Citric acid will break down by bacteria, and then the pH will be way higher than what you've started with, at least in my experience.

I recommend you to buy proper pH down, usually based on Phosphoric acid.

Also, definitely use pure water, e.g. rain, distilled or reverse osmosis.
Tap water has a lot of minerals in it, which add a lot of "crap" to your nutrient solution, which will cause the nutrient lockout you mentioned you had with your tomatoes.

I tried anything (boiling, diluting, whatever) and always came back to pure water, because I always had problems with tap water (Germany, like you).

pH swings and deficiencies, even at proper pH, are pretty much guaranteed, at least from what I've heard and experienced. If you have a crap load of calcium, acids in there, they will complete with the nutrients.

Does it make sense to follow some generic approach (like keeping pH/EC in certain ranges in certain growth stages)?

Half the recommended strength (or just pure RO water) for seedlings, normal strength for everything else that's leafy (houseplants, growth phase of veggies, etc.) and 1,5-2x strength for flowering or fruiting plants.

I personally run ~ 1,0 mS for most stuff, and 1,5 mS for flowering.
Measure the EC regularly, and if it lowers, add more fertilizer next time.

Depends on your humidity/ evaporation and light intensity.

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?

I use Masterblend for everything and like it a lot. Weed, houseplants (orchids, calathea, etc.), you name it. They all thrive.

It's cheap and works well. Maybe I'll change my mind someday, but at least for now, I can recommend it.

I made a life hack post on how I dose it if you're interested.

My advice for you in general is to invest in proper hydro stuff and not to find workarounds for everything. I tried that and failed miserably.

[–] zenforyen@feddit.org 0 points 1 year ago* (last edited 1 year ago) (1 children)

Thanks for the great reply! I just assumed that this community is probably bigger, but yeah maybe next time I should ask in the German one, talking about plants in english not knowing a lot of normal words from gardening is a bit annoying :D

I see that I have mixed up a lot of things, between things relevant for soil and hydro. So your recommendation seems to be not to try to mix because it is counter productive, and if I use some compost-based approach I should stick with organic fertilization? I guess I could try to do that on the balcony, where the plants will live by the normal sun and weather cycle. Then I'm gonna research a bit more about organic fertilization too. Soil feels like a "black box" and more of a vibe thing than an exact science and that makes it somewhat hard for me to get into.

Indoors I'm pretty interested in doing "hydro" in coco coir, because I can store a lot of it dry and compact in the basement for years and not worry about insects or mold.

With hydro stuff however I am worried that I become too dependent on some "fertilization system" supplier and if I only learn to paint-by-numbers I don't learn any transferable knowledge, even though hydro seems to be much more precise. Like, are there vendor-independent hydroponics recommendations per plant? Or you always just pick some fertilizer brand and follow the instructions, regardless of plant? And I can read info about hydroponics and apply it to growing in coco or something else which is non soil or are there some caveats? Because I'm not planning to have a hydro tank system, just interested in non-soil substrates.

And a very stupid question: is "compo complete" a soil or a mineral fertilizer? I thought it was mineral which is intended for soil, and now I'm confused as you said not to do such things. Thought organic fertilizer must be some worm humus or plant material or other stuff they add into soil, like indirect complex compounds of something decaying which is broken down by micro organisms, and that liquids are always mineral NPK mixes with immediate availability, or is that assumption completely wrong?

[–] Guenther_Amanita@slrpnk.net 0 points 1 year ago (1 children)

I see that I have mixed up a lot of things, between things relevant for soil and hydro. So your recommendation seems to be not to try to mix because it is counter productive, and if I use some compost-based approach I should stick with organic fertilization?

While organic vs. "hydro" is more of a spectrum and in some cases hard to define, I'd say it's better to clearly separate them to get the most benefits out of each concept.

Soil feels like a "black box" and more of a vibe thing

That sums it up very well.
When growing organically, you can let the microbes (and small critters) do the work for you. You don't know what they do, but they just do stuff, and you don't or can't worry about it.

It's more of a layed back thing.
Weeds now don't exist anymore, they're now just called "cover crops", and pests don't demolish your crops, they're just waiting to get eaten by other beneficial insects 😁

Indoors I'm pretty interested in doing "hydro" in coco coir, because I can store a lot of it dry and compact in the basement for years and not worry about insects or mold.

Maybe read my guide on passive hydro with LECA. It has similar benefits, but is completely inorganic and my substrate of choice.

become too dependent on some "fertilization system" supplier and if I only learn to paint-by-numbers I don't learn any transferable knowledge

Fertilizers are mostly the same. They all use the same ingredients in one form or another.

You can easily switch from T.A. to Plagron to Masterblend for example, that shouldn't be much of a problem.

You still need to get a bit of experience, but I find it way easier to diagnose problems and trends.

And I can read info about hydroponics and apply it to growing in coco or something else which is non soil or are there some caveats? Because I'm not planning to have a hydro tank system, just interested in non-soil substrates.

While the two disciplines seem to be separated from each other, you can still greatly benefit from mastering both.
For me, hydro mostly just means soil-less.

I thought it was mineral which is intended for soil, and now I'm confused as you said not to do such things. Thought organic fertilizer must be some worm humus or plant material or other stuff they add into soil, like indirect complex compounds of something decaying which is broken down by micro organisms, and that liquids are always mineral NPK mixes with immediate availability, or is that assumption completely wrong?

You are correct. The effects of synthetic fertiliser on soil is sometimes a bit exaggerated. Microbes are kind of tolerant to minerals, it's just that you steal their jobs and weaken the connection between them and the plant. Read more about mycorrhizal networks if you're interested in that topic :)

[–] zenforyen@feddit.org 0 points 1 year ago

Can you provide a link to your "passive hydro" guide? Sounds very interesting :)

In general I'm interested in learning some non-soil method that is still forgiving, does not need special tech (like pumps and stuff) and ideally not much more maintenance than a soil grow. Maybe I'm asking for something impossible.

Btw, I do have Tropf-Blumat and was going to set it up indoors anyway, to automate and optimize watering. not sure whether it helps for hydro, if you always have to supply nutrients in the water (I would not put nutes into the normal watering tank). I got that, full spectrum lights and ventilation. That's as "high-tech" as I wanted to get :D

I guess in any case I'm going to try Plagron or Masterblend then, you convinced me! Maybe I should not make my life more difficult than needed when just starting out.

In any case, thanks for the patience with a total newbie :)