I started mine using 80mm pots, it was fine to start with but as the plants got to about a foot tall they kept toppling over and the net pot got fully submerged, only good thing is the roots growing thru it keep it together, now they r about 5 feet tall it's a nightmare, I have tied the stems so they can't fall over, my new ones have been put in 120mm net pots, just the weight of all the clay pebs makes me think it will be quite stable, but as a precaution I have litterally bolted the net pot to the lid of the bucket, I will post some pics if anyone wants to see em!!!