There are 2 main schools of thought when using soil and many hybrids of the two:
1. Feed the plant nutrients
2. Feed the soil, not the plant
Many growers do more of an 'all purpose soil' approach using their soil as a base medium with some nutrient value but they mainly rely on added fertilizer nutrients in routine feedings. The type of nutrients are then tailored to the required needs of the plant as it goes through all the growth stages. Many organic growers prefer to tailor the soil mix for the various growth stages and change up their mix as they transplant their plants into new pots when needed. For most seedlings as well as small clones of more sensitive strains, a rich organic soil like Foxfarm Ocean Forest is often a bit too 'hot' or strong for them to to their best at that stage of growth and they'll show signs of nitrogen burn on the leaf tips.
Many growers use less hot soils for seedlings and to start clones of sensitive strains. After vegging for a few weeks they transplant into a slightly larger pot with a more 'hot' soil like FFOF. They let the plants veg a while more and then just before putting it into 12/12 the plant goes into yet a larger final pot for the bloom cycle. The soil mix for bloom is amended with organic P & K sources such as fruit bat guano, bone meal, blood meal, rock phosphates, etc. and there you have it... Three soils for one plant!
There's a somewhat infamous grower/breeder who calls himself Subcool and he uses a combination of soils in one pot. He does longer 6-8 week veg times to get large indoor plants. When he transplants his girls into their final 10 gal pots that will last the rest of the grow he puts a very strong 'bloom' super soil mix (with organic soil amendments like those mentioned above) in the bottom half of the pot. He mixes in a high quality potting soil (he likes Roots Organic) with the 'super soil' for a 50/50 soil/super soil mixture that will be the middle 1/3 layer of the soil in the pot. The top 1/3 layer of soil in the pot is straight Roots soil. He puts mainly Roots soil around the holes he puts his plants in. As they continue to veg in those pots the roots gradually grow down into the stronger soil and after he puts them into 12/12 the roots start to reach the full strength PK nutrients. Throughout the plant's bloom cycle they will only be fed water. They will get no added base nutes or PK additives but do get a periodic feedings with Botanicare Liquid Karma for humic and fulvic acid. If the strain goes long on the bloom calendar and starts to depleat the nutes in the soil, Subcool top dresses with some of his 'super soil' and waters it in. Subcool gets amazing results with his completely organic soil method and he is all about feeding the soil.
Peace!
