I am currently about three weeks into flowering of my first grow. When I got started I planted my seeds in 3 gallon pots that are about 18' tall x 12" width. I assumed that they would be plenty large but now that the plants are about 6 feet tall, the pots are beginning to look undersized. My question is, how much soil in width and depth is ideal for the best growth? If I just built a raised bed in my grow room that was approximately 8' x 8', how deep should the soil be? Would I have to separate the sections of the raised bed for each plant?
to prevent rootbound plants in flowering either go in ground if your outdoors or just do a pot transplant before flowering. If you want to flower in 3 gallon pots, then veg them in 1 gallon then transplant to 3 gallons before flowering. i know some people that wait a week after transplant to officially switch to 12/12 and i know some that transplant and start 12/12 the same day thats up your call, me personally i wait about 4-5 days
FRINGE! While there are plenty of growers out there that will say a deeper pot is better than a wider pot, I personally have seen no difference between the two. Soil volume is what's important, IMO. And you're right. A three gallon pot is way too small for a 6 foot plant! My plants usually finish somewhere around 4' tall (top of soil to top of plant) and I grow them in 7.5 gallon smart pots. They start in a 16 oz. beer cup, then to a 1 gallon, then to the 7.5 gallon. As far as the raised bed thing goes, this link might help. Keep in mind that the growers that use raised beds like this grow in hand crafted organic soils. They use the same soil for several grows before replacing it. I don't think this method will work well if you use chemical fertilizers. http://boards.cannabis.com/organic-growing/81991-somas-organic-growing-bed.html And if you're interested, this is how you go about making your own hand crafted organic soil... http://forum.grasscity.com/organic-growing/1116550-easy-organic-soil-mix-beginners.html
It's relative -- what you really want is good depth and width. There is a point where trading off one against the other defeats the purpose. For example, 3 gallons is 693 cubic inches, so if deeper is better than a pot that is 1" wide x 1" across by 693" deep (almost 58 ft) would be best, right? Of course not. To the OP, not sure about your pot measurements though. 18" deep, let's say they expect you to leave 2 inches at the top so 16" of soil depth x 12" of width would mean the third dimension would need to be under 4 inches to total 3 gallons. Regardless, if you want a bigger, healthier plant then aim for more root volume, not just deeper root volume.
I guess what I really meant to ask is how much soil is beneficial to the growth of the plant. Theoretically, if you had 10 feet of soil, would your plant grow stronger and more robust than a plant in 2 feet of soil?