Unlike the other suites, heat is not an ingredient in a compost pile. You can't add heat, heat is the result of building a good pile. Those black plastic compost bins one sees in the garden catalogues only serve to dry a pile by cooking moisture out. Although you must have a red card to win, it could be a too cold, a too hot or a just right card. Improves aeration and mixing.
Gold represents beneficial ingredients and activities.
There are ten gold cards. Pet waste can carry worms, bury under a tree or trash 'em. Oranges are either bad ingredients or pests drawn to the pile by poor composting practices. Because they don't fit in the compost hand they are usually discarded early in the game. They can also provide frustration when drawn later in the game as the players search for those last necessary cards.