World's largest plant container?
I turned my in-ground swimming pool into what might be the world's largest planter/container. Like a planter, my pool now has some drainage holes in the bottom of it. And it holds dirt. A lot of dirt. About 7 or 8 large truckloads of it or about 15,000 gallons of dirt.
It's surrounded by a tile lip and a flagstone patio, so it stands out from the rest of the yard.
As a bonus, it has a small spa/hot tub section next to it that was also built into the ground and covered with tile and stone. It's raised slightly, so it looks even more like a plant container. It only holds about 400 gallons.
And as an extra added bonus, the pool came with a large rock waterfall at one end that is now a landscape feature. It has several areas in it that are planters as well. It holds maybe 10 gallons.
I hope that these "planters" will eventually hold a half dozen large trees, plus assorted shrubs and other plants.
Is it the world's largest plant container? I don't know. I did a Google search and found a 1/4 ton hanging planter basket in front of a hotel in London. I think mine is larger, though.