Every player begins the game with five Natural Pasture Paddocks on their property, stocked with three Sheep Pens in each Natural Pasture Paddock. So that’s 15 Sheep Pens in total across the five Natural Pasture Paddocks to begin with.
You ALWAYS have FIVE PADDOCKS to your property. Never any more or any less than five paddocks. So when you buy your first Improved Pasture you have Improved that paddock from Natural to Improved. You then have four Natural Pasture Paddocks and one Improved Pasture Paddock.
You need to BUY Improved Pasture paddocks (green) before you can move your sheep from your Natural Pastures (orange) to Improved Pastures (green).
Once you have paid to Improve all five of your Natural Pastures (from orange to green) you can then begin buying Irrigated Pasture cards to upgrade your five Improved Pastures to five Irrigated Pastures.