Asparagus season peaks in spring, between February and June. However, they are available year-round from international sources. They come in colors other than green; be on the lookout for purple and white varieties, too. The size will depend on when it was harvested; the wider spears have had more time to grow. The long stems should be bright green in color and firm, the tips should be closed, and the skin should have a smooth and rubbery sound when the bunch is squeezed together.