Paka nailed it down!!! This is a reason why I take a gazillion pictures of my grow so I can go back to learn difference.
Here is a plastic container roots, this was my Cougar Male plants root zone. See how they spiral, NO GOOD!!! Root bound problems!!!
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Here is my beast and look how small he medium is and you dont see the spiral affect.
To me I only use the plastic container as starters but since I been buying these cheap ass Dirt Pots (which is a mock of Smart pot) I wont use plastic containers no more. You can grow a much bigger plant in a fabric/air pot than a plastic container anyday. I be willing to challenge someone on it, They can use a 3 gallon plastic container and I will use 1 gallon Dirt Pot of mine and I will bet my 1 gallon plant will be larger than a 3 gallon plastic container plant.
Here is another example I got:
This fabric pot was made by BC99 with his sewing machine, it was less than a 1/2 gallon. This pot was almost the same size of my Coffee Cup.
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The plants on the left are in a larger container but its the plastic square, I think it was a gallon container. Look how much more plant I got out of the smaller fabric pot...
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To me the proof is in the pics. No need to by brand name shit when if you have a sewing machine, make your own pots!!! They work!!!
Hope that explains what Paka posted. He was right on, I do use N.U.T.S or Fulvex from time to time but majority my plants get the baseline X Nutrients and Silica Shield. Silica Shield is the BOMB!!! Oh by the way, the Fulvex, N.U.T.S and Silica Shield were all free samples I got from companies online. Register on all nutrient companies and request for free samples. I even got ZHO, Great White and Orca sent to me last week. All free!!!
EDIT: Dont waste your time with Fox Farms, cheap bastard make so much effin money on their shitty nutes they wont send no free samples!!!
Peace
FM