The most famous (and expensive) ice wines are German Eisweins, but ice wine is also made in Canada and the United States. Natural ice wines require a hard frost to occur sometime after the grapes are ripe, which means that the grapes may hang on the vine for several months. If a frost does not come quickly enough, the grapes may rot and the crop will be lost. Some winemakers use cryoextraction to simulate the effect of a frost, but typically do not leave the grapes to hang for extended periods as is done with a natural ice wine. Perhaps the most famous of these is Bonny Doon's "Vin de Glaciere" (icebox wine). In Germany and Canada the grapes must freeze naturally to be called ice wine.