How much you yielding in 11 gallons? Also, how much time difference to harvest comparable to 3?
In one 11 gallon pot last year I planted three regular autoflower seeds expecting to have to cull some male seedlings. All three ended up being female. Two phenotypes could be expected according to the breeders. I got both phenos. Kilter strain from Afterthought Autos. They are not a fast strain.
One appeared to be almost a photoperiod pheno, produced a tall plant that appeared to be sativa dominant. I had it written down how much I yielded from that pheno but I probably tossed it. I filled around 4 quart jars, a couple pint jars from that plant. Probably 50 to 60 inches with numerous branches with two to three inch buds.
The other two plants probably yielded two ounces each, appearance was more of an indica look. The two plant had large central colas with smaller side colas. No taller than maybe 30 inches each. Central colas were as long as my forearm. Three plants in one pot, grown under natural sunlight from seedlings. Very little care. Probably 12 ounces total.
The plants were put outside in June when night time temperatures were still in the high 30's F. Two shorter phenos were harvested in late August. Tall pheno harvested in late September I believe. I gave them nutes but did nothing else. No topping or stress training.
I posted pictures here at the time but I couldn't access my account due to the upgrade of the site last year tanking Facebook sign ins.
I didn't grow this strain in a three gallon pot so I can't compare this strain.
As far as some Fastbud strains I grew in both pot sizes. Some grew so big in 3 gallon pots that the roots were growing out of the soil. Just a mass of roots, rootbound? Huge plants but only 1 1/2 ounce harvests. Had to water 2 to 3 times each day. Larger the pot, I could go days without watering. These were outside grows. Start in tent, move outside once established.
As far as the 11 gallon pot with the three plants. I had read here that you can't grow more than one plant in each pot but the three plants grew fine, considering two of the plants were a small pheno and harvested a month before the large pheno finished.
I harvested 1 lb from the single photo plant I grew, after losing a few ounces to bud rot from the top colas that were huge. That plant was planted straight into ground after transplanting from 2 gallon pot. I filled two half gallon jars from that plant, some quart jars, some pint jars. It seems much more potent than the autoflower plants I grew. I did a hash run from some of that mixed in with some spindly Fastbuds Gorilla Glue that resulted from a three gallon pot. The Fastbuds was a large plant that I accidentally planted in a three gallon pot. It took four months to mature in that small pot, big plants but buds were small. I threw the one ounce I got from the GG into my hash run and the hash is killer. Used another ounce in some cannaoil I made in my Infuzium 420. Very potent. But the buds were so spindly I didn't even finish harvesting that plant before frost killed it. Probably two ounces still left on the plant out in the snow when I last looked at it. I should have cut the plant down and put it in a bag in my basement freezer but I had two pounds of good weed I was busy trimming and drying at the time.
I only smoke about an ounce or two in an entire year. I don't even know what to do with two pounds. Not legal to sell without a state license. But you can gift 2 1/2 ounces to anyone 21 and older. You can only eat so many pot brownies.
Fastbuds in 3 gallon pots took about a month longer to reach harvest versus the same strain in 7 or 11 gallon pots. With Fastbuds I do some topping.
My photo plant planted straight in the ground I did topping, stress training to keep it under 6 feet tall. Did frequent trimming of fan leaves. Had colas so huge the plant split in half a month or so before harvest. Duct taped it back together and had to use straps to tie the plant for support. Gave me a huge harvest compared to the 20 autoflowers I ran last Summer. I going to grow mostly photo plants this year. In ground or 11 gallon pots. Will be pollinating them to get regular seeds. Might cross them with the Kilter autoflower just for kicks.