Are 3" net pots big enough from seedling to harvest ?

Can i do the 3" the whole way through harvest ?

depending on the plent size 3-4 feet yea no prob 5ft + might get a lil tipsy

thats what i use and other use too

that size wont' prevent growth ?

I would go as far to say it wont prevent growth as its the roots that search for food and by doing that they grow down..

Ive used 3" before using chillis and tomatos and compared to the 8cm im using now, theres no difference..

it does not prevent growth but as the plant gets taller it also gets wider and needs a more stable base 3" net pots will want to tip over or come out of the hole if the plant gets 5-6+ feet. A larger net pot gives plants a more stable base only imo so if your doing sog or smaller plants go for it but if you want monsters i would say get bigger ones