That’s actually pretty good:
(3 * 35) + 25 $ / 2 crops = 65$ / crop
65$ / 32 ft² = 2.03$ / ft²
It’s actually probably cheaper than that because your flood table probably only takes up 80-90% of your grow space.
Even if you used 4 bags of Canna coco you’d still be significantly cheaper than the rockwool I’m using.
I thought bagged coco would be pricier, so that’s definitely interesting info.
One theme I’ve noticed emerging so far is that: Perlite is cheap!
yes i was initially going to run 6 inch rockwool cubes but i was quoted some redic prices and i think lowest i could find was like 2 bucks per cube in bulk. with no re using makes it double the price. i think coco might have gone up because i was paying 30 but now some places 35 or 40. i also go 50/50 with perlite to double the volume.
also i use 1 gallon pots but i bet i can get away with half gallon pots or 0.8g for my style and save even more.
How do you irrigate this mix, in your 1 gallon pots?
hey was flood and draining when i use coco. was the easiest for me and cheapest
When running rockwool, I go to harvest in 4" cubes, 1 per square foot, so 25 per light.
They cost a little under a buck each, so its about maybe 22 bucks per light per run.
Our metric is based on cost per ounce. We used to spend $400 an ounce, so I calculated up everything, cost of media, dry amendments, EWC, bags, perlite and average cost of a seed. Then, I looked up our cost per KWH and multiplied it by the number of light on time hours in a cycle of 4 plants, based upon our light draw at the wall. It averaged out to $14 an ounce if we pulled at least 6 ounces from each plant. Obviously, the cost per ounce is proportionally less if any one of them produce more in the same time frame. We don’t reuse anything. Every run is a start from scratch and we’re still saving a small fortune.
That number does not cover the cost of any of the equipment. Lights, fans, blowers, tent, etc. We were in the black on that within the first 6 months of legalization because of the money we weren’t spending on black market weed.
Yes.
People ask me “how much does it cost to start growing?”
I answer “that’s the wrong question, how much do you spend a month on weed?”
I include depreciation of gear in my calculations and I haven’t done the math in a while but it’s something like 25 cents a gram.
Last time I checked it was 16$ a pound or so…
If I include my time it’s 18k a pound. GL 
Yeah that’s the real killer there.
I use coco. Costs me about $25 (with tax) for 40L (10 gal)
I use 8 of them per crop and flower in 150sqft
$200/150sqft = $1.33 per square foot
150sq-ft of canopy?
Yes 150sqft of canopy. The room is a little bigger but I leave the extra space for, tools, equipment and to roll my tables in and out to get around the plants.
im on like my 25th run with the same batch of promix 
For 10sqft. Or 10, 2-gallon buckets of perlite its about 35 bucks for new about 15 bucks if I reuse what I can reuse. ¹
you grow in pure perlite?
yes. for about 10 years now. i kept reducing my soil content and was getting better results. when i got to 50% soil i said screw it…let’s just cut out what is holding us up.
Gonna check out your thread for details. I never had any success with pure perlite (setup a tomato hempy for someone recently, didn’t go well). Don’t think I tried one personally, with cannabis. I think the irrigation is the tricky part.
no tricks. it’s idiot proof. if you use a 2 gallon bucket with a hole at 2inches from the very bottom, your plant will drink it all every 3 or 4 days. it will be dry. you will have to add more water. you can add peroxide 15 to 30 ml per gallon if you smell something is off. you also need coarse perlite, like #2 to #3 so that it drains wells. and it needs to be washed well. don’t use super coarse perlite, like tic tac size to half tic tac is best. i’ve done a little smaller, like # 2 and it was ok, but you need to wash it very well.
i’ve used a 5 gallon in hot temps like outside and i got smelly roots, but i was able to wash it out with about 5 gallons of water with the peroxide in it. it went back to normal.
I find it doesn’t “retain” moisture, laterally, enough. That, in combination with improper/poorly optimized irrigation (even, slow watering over the entire container’s/media surface) means water just flow straight down to the res., and roots don’t develop laterally and fill the container width nor the height. I didn’t like it at all, but I didn’t have a good way to water better. I know some do amazin in bato buckets though, growing tomatoes, so I’m far from an expert in pure perlite. I like the idea, cost wise though. But I hate perlite for certain reaons, even though I cut my coco with it, currently.
mine stays moist until right before next watering. maybe you aren’t using the right perlite. most plants have lateral roots.