On a modern small or large scale farm, greenhouses should be thought of like your best employees, they will grow along with your greenhouse farming business. Tomatoes, beans, vanilla, fruit trees, lettuces, and other high value crops can be grown in a greenhouse much more successfully than outside in the elements. All seedlings should be started in a greenhouse to ensure a better germination rate and an earlier start to your season. Greenhouses allow farmers to control their own weather. Weather has plagued farmers for millennia, but the unassuming greenhouse is changing that. Greenhouse farming is perfect for an unpredictable climate. In Kenya, greenhouses are being used in response to their recent severe climate shifts with surprisingly excellent results. At their essence, a greenhouse is just a glass box that allows solar radiation in, but does not allow heat out. Since most plants grow quickly and robustly at higher temperatures, a greenhouse can turn a marginal plot of land much more profitable. Planets in our solar system actually act as giant greenhouses, the most efficient being Venus where temperatures at the surface exceed 863 degrees farenheit. The greenhouse effect makes Venus the hottest planet in the solar system, even though it is not closest to the sun. Many farmers are now experimenting with aquaponics, which adds fish into a greenhouse system. The circular closed-loop system allows the fish waste to be reused as plant food, and the plants in turn feed the fish. This system produces better pound per foot productivity than any other farm system to date. Greenhouse farming is both small scale and enormous scale. The largest greenhouses cover multiple acres, while the smallest can fit within a window — in fact a window can be thought of as a tiny greenhouse, because it performs the same heat trapping function. The cheapest form of greenhouse per acre is the high tunnel greenhouse, which is open on each end, and made primarily with sheet plastic and curved plastic or aluminum piping.