Last summer I found myself with a dozen pumpkins and no plans for what to do with them. I ended up giving some away, and using the rest for porch decorations. After a couple of hard freezes, they were ready for the compost heap from which they sprouted about a year ago. I retrieved some seeds (a messy job after the pumpkins go soft) because I have real plans for them this year. I'm going to experiment with geometric pumpkins!
The first time you see square watermelons, your instinct may shout "Photoshop!" but they are really square. Not a genetic variant, these are made the old-fashioned way. They are grown in boxes, and take the cubic shape gradually as they grow. It's a labor-intensive process, but the end result fits nicely in a refrigerator, and wastes no space in the truck. And they won't roll around! They've been growing them in Japan for years, because space is at a premium. The watermelons are at premium prices, too.
To achieve such results, you have to have a proper box, made of tempered glass or durable plastic. Transparent boxes are best, or else you won't know exactly when to harvest, or even worse, waste your equipment on a rotten fruit! K-mac Plastics sells boxes especially designed to grow watermelons in, complete with proper drainage.
Keep reading for even stranger shapes
The idea can be carried over to other types of garden produce. Have you ever heard of a cubecumber? The shape is even more impressive when you slice them for unsuspecting guests.
You can order a kit that helps you to grow your own square tomatoes. Grow Big Strange and Nasty Plants has five projects for kids, with a giant pumpkin project and an insect-eating plant as well as a cube tomato kit.
You can also buy molds for your garden. Vegiforms offers two-piece plastic molds with faces on them. The garden elf shape and the "pickle puss" shape work with eggplants, zucchini, and other roundish vegetables. The diamond and heart shapes are longer, and produce the shape when you slice the cucumber or squash. There's even a mold in the shape of an ear of corn, so you can disguise one vegetable as another!
The greenhouse at Disney EPCOT in Florida grows vegetables in the shape of (what else) Mickey Mouse.
This photo, supposedly of "miraculous" roots that were pulled from the ground in the shape of two people, has been making the rounds for quite some time, most recently at the Daily Mail. Skeptics say they couldn't have grown that way, that they must've been carved. But the filament roots seem real. Once you know how it's done, it seems simple (but isn't). With the right mold (possibly dolls), the real miracle is getting the roots to grow so large!
I saw instructions at one time about getting a pumpkin to grow inside a square milk carton, but it seems you would have to support the outside to keep the plastic from bending. Hmm. I may experiment with getting a tomato to grow in the shape of the inside of a jar first. However I decide to do it, rest assured I will take pictures for you!
Update: I tried molding pumpkins. Here are the results.