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?
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 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.
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.
“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.