Tractor Supply Company stores sell highly compressed bales of straw, which are shrink-wrapped in plastic for easy transport. Before conditioning these bales, you will need to re-tie new strings around them which are not as tight, and thoroughly soak the bales with water so that they expand in size. Tractor Supply Company stores are also a great source for the cattle panels, fence posts and other supplies we recommend using to build your own 6-week Greenhouse.