I've managed to get a full pound from a single plant growing in the closet.
The closet is 21" X 21" and the plant can grow to 4 feet tall.
This last plant was a Dud.
I didn't even bother weighing it. It loosely filled a single 1 gallon jar, but a one pound plant fills 2½ one gallon jars.
And the weed sucks too..

It barely gets me stoned.
I don't know what happened?
I've grown the same plant before from the same batch of seeds, but this one was crap.
I got started really late too, because I ended up killing 3 seedlings before I got one to grow, wasting more than a month of time.
It's best to grow in the winter with the lower humidity.
High RH can easily lead to mold
postless design.
Ohh,.. And buy Autoflower Femininized seeds, so you don't have to be concerned about light timing, or growing boys.
Regular seeds and plants can herm on you with the slightest light leak, then you've got male flowers on the plant, it pollinates itself, and you've got a plant full of seeds.
Autoflowers are WAY Easier to grow.