Universal Seasons is a set of resourcepacks, that allows you to choose between different seasons in Minecraft. The different seasons result in different colors applied to grass, plants and leaves. Since the seasons are biome specific, each biome features other color gradients.
Since it is using the custom colormaps feature introduced by OptiFine, this resourcepack requires an installed version of OptiFine. As the name already says: Universal Seasons is universal! This means that Universal Seasons is compatible with all resourcepacks, that use "tinted" textures for their organic textures. It can be used as an add-on and can be added on top of the preferred resourcepack, such as PureBDcraft, Faithful, Soartex Fanver, Dokucraft or any other common resourcepack. Of course this pack also works with the default Minecraft textures...
You are already convinced? Great! Then you can download Universal Seasons here and choose your preferred version.
You want to review Universal Seasons or you just want to know what you can do with the pack? Then check out this legal information.