At dinner, a youthful old friend wondered how much plant material could come out of an 8'x12' greenhouse. That triggered some mental activity.
Above, each plant is in a 2x2x2 cube of compressed potting mix. The cubes in the foreground were seeded a month ago and those in the background about 10 days ago. The cubes in the foreground comprise a block of 20 columns wide and 12 rows deep (each column a different plant or variety); the same for those in the background. The foreground plants are ready to plant out. In fact, two days after I took the photo, they are about half gone, having been distributed at the community garden and to a couple of regular receivers in Berkeley. The remainder will go into my garden or be potted into recycled paper cups for further growth outside or on a lower shelf of the greenhouse.
So ... that's 240 plants to plant-out or pot-up maturity every two weeks. Assuming (as has turned out to be the case) that I take a holiday from production in June and July, that makes for roughly the potential for 5,000 plants per year.
I don't produce 5,000 plants per year, but I may reach half or two-thirds of that number. In reality, there are germination failures as visible above (I hate to toss old seed!), some plants that need more than two weeks before plant-out or pot-up, and some that just end up being surplus to my needs and I don't find a home for.
And that's just one of six of the benches in the greenhouse, so with a little tighter management the theoretical potential is for 30,000 plants per year.
Room for growth in a room for growth.