Because, of course, it's the feast of Saint Patrick. Going green for St. Patrick's Day is a great example of packaging power. Slip those old computer programs into green sleeves. Sprinkle Lucky Charms on ice cream concoctions. Get a bulk order of spray paint and re-do those bookcases, computer hutches and TV consoles gathering dust in the warehouse.
Color coding is a great marketing tool.
Just to keep you up to speed, here's a handy chart of seasonal colors. There are still some colors left.