In this phase, unoccupied populated tiles are active.
Each City, Town, Farm and Outpost tile may gain one powered building if the total niceness of its surroundings is greater than the tile's current power. If there are buildings without power on a tile, those will gain power before the tile gains more buildings.
After all City, Town, Farm and Outpost tiles are done growing, Barracks and Industry tiles can grow. For each such tile every City tile owned by the same player provides one point of niceness per powered building.
After all Barracks and Industry tiles are down growing, Airfield tiles can grow. For each such tile every Industry tile owned by the same player provides one point of niceness per powered building.
Each building type has a maximum number of buildings possible on a tile.
Then, every City, Town and Industry tile generates income for each of its powered buildings and every Crops tile is consumed for income.