It's no mystery that different plants need different amounts of light. Some are even happy to spend their whole lives in the shade. The dark areas of your garden and house are easy to find, but others aren't so clear. How can you know whether one plot gets more sun than shade, or vice versa? That's where the Sun Calculator comes in. Leave it in one spot for 24 hours and it will tell you how much light the area gets. Plant your message bean accordingly.

There are several drawbacks to this clever invention. The first is that it costs $30, a pretty exorbitant price for something that has less technological savvy than a solar calculator. Furthermore, we imagine that the calculator would be useless on rainy or cloudy days, but that if you planted it on a sunny day, it wouldn't take inclement weather on other days into account. Finally, hang out in your garden a few times. You'll probably figure out everything you need to know on your own. — S.E. Kramer

Sun Calculator, via Boing Boing Gadgets