Ok thanks, I knew that the YOUNG seedlings don't need any nutrients, that why I wanted an organic soil additive, takes time to break down (unless it's dried blood). I was mostly concerned with it for when the plants are like 2 weeks old and need to be transplanted, but if you think nothing is better I will stick with that.
Pretty much all modern good quality peat based compost soils have sufficient nutrients in it to last on average anything between 3-4 weeks of nutrient use by the plant, why do we want to add to that? There are some organic soils that haven't been composted for long enough that don't contain sufficient nutrients for that length of time, but they're just poor performing soils and should be avoided.
The modern thinking on growing these plants is that less is more. The more natural the plant environment, the happier the plant will be and the larger the yield will be, that means among other things not force feeding large amounts of nutrients, because plants can burn and can be stressed by high levels of organic nutrients, it takes longer than chemical based fertilisers but it can still happen very easily. When this happens the plant then has to spend time repairing the damage done to it by the overfeeding and that means its energies cannot be put into producing flowers if in flowering or vegetative growth if in that stage - this in effect stunts or stops the growth of the plant for a week or more whilst it repairs itself.
To grow the healthiest looking plants the grower has to understand fully and comprehensively the plants environmental needs and requirements. This means providing a clean, sterile growing area lit by the correct number of lumens for each stage of growth and ventilated correctly for co2 replacement, temperature and RH control. Once these are correct, the health of the plant is very much in the hands of the skill of the grower.
The key to all this is watching the plant very closely and letting it tell you what it needs. I don't mean wait till a leaf drops off because its gone all shrivelled up! I mean watch for the tiniest signs like leaves losing their sheen, shine and lustre, tiny little yellow tips to the leaves, a slight curling under of the leaves a slight curling up of the sides of the leaves, small leaf serrations turning brown, these are all signs that something isn't right and it takes time and experience to watch for them. If you can spot these signs and interpret what they mean in your own instance and situation you'll be well on your way to understanding plant needs and requirements and be able to take the correct course of action to stop and prevent plant problems before they develop.
Guessing at what nutrients to feed at what level and what stage isn't really going to grow you healthy plants.
