3 gallon pots should be just fine on a plant only vegging to 18 inches i veg mine taller then that in 3 gallon smart pots and get NO root problems......Brick Top says " never use 3 gallon pots" thats rediculaous advice not everyone wants to grow outside and use hudge pots and veg for 2 months theres all kinda of ways of growing with less then 5 gallon pots....Unless you are going to veg for like 2 months and plan on growing 6 foot tall plants you dont need 5 gallons pots....... and it dosent even make sence that your plants could be root bound in 3 gallon pots at only 18 inchs tall thats CRAZY and iver never heard of such a thing happing....i mean 18 inchs that ALL?? and there root bound?? na dosnt make sence really i mean i use to use 2 gallon pots and still get no root bound so i just cant see how your 3 gallon is root bound already
Along with four members of my family I am an owner of a pot-in-pot nursery that covers about 17 acres of land. We have thousands and thousands of trees and bushes in pots. My four family members all have degrees in botany. I have 38 years of herb growing experience, that's nearly four decades of her growing experience. Between what my family members with degrees in botany know and have taught me, with what we have learned over the years at the nursery and with my 'home gardening' experience I know about growing in pots and I know what plants need and how plants will react when grown in pots that are too small.
I am more then used to reading messages attempting to refute what I say, and they are always by people who do not come anywhere close to my level of expertise or amount of experience or degree of botanical knowledge.
So believe whoever you prefer to believe. If you prefer to make mistakes it will never cause me any problems.
Oh ... when you said; "Brick Top says " never use 3 gallon pots" thats rediculaous advice not everyone wants to grow outside and use hudge pots and veg for 2 months..." that was highly inaccurate. I said I will, but seldom, use pots as small as 5-gallon pots for indoor growing but normally will use 7-gallon pots indoors. The larger pots, 15-gallon and larger, are what I use when I grow on my deck.
Normally I will veg to around 15 to 18 inches and when I do that using 5-gallon pots when I harvest and check the root-ball it is getting very close to being too tightly packed. When I use 7-gallon pots, and veg the same, there will be roots in every area of the pots but they will not be tightly packed. There will not be any area without roots, no part of the pot goes unused.
When I grow outside, and use the full southeastern growing season, by harvest there is no extra room for roots in my 15-gallon pots. They are not root-bound, but they are not far from it. In 20-gallon there might be a slight amount of unused soil and in 25-gallon pots there will normally be roughly two to three inches at the bottom without any roots at all, but the roots will have grow all the way to the sides of the pots, just as with the 20-gallon pots and with the 15-gallon pots.
Healthy plants will have a 50/50 ratio between overall leaf area and root-mass area. There is as much growing under the soil as there is growing above the soil, if the plant is healthy. Of course the shape of the different growth is completely different, but the amount of area, the total mass will be as close to being a 50/50 ratio as possible.
If roots are not allowed the space they need the plant will never produce as well as it otherwise would. Never.
Where uneducated, in botanical matters, and inexperienced growers become confused is because the cannabis plant is a rough tough species that will take a licking and keep on ticking and because of that they can be abused and still produce well enough to impress some people. Because of that those people will incorrectly assume that they did well and that they grew their plants very well and that they maximized their production. But they are wrong.
The only way to achieve optimal results is to provide optimal conditions for plants to grow in and small pots do not provide optimal growing conditions.
Everyone is of course totally free to believe whatever they prefer to believe and if someone want or needs to believe that small pots are perfect or best for growing in, that is of course their right. But they would be totally wrong to believe that just because they choose to believe that, that they are correct and that their personally chosen belief creates fact and that their personally chosen belief somehow magically and mystically transforms scientifically proven botanical facts into fiction or inaccuracies.
Like it or not, accept it or not, that is reality.