1. Combine the potatoes, onion, coriander, granulated garlic and onion, poultry seasoning, and 6 cups water in a large soup pot, and bring to a boil.
2. Reduce the heat to medium, and add the broccoli. Cook covered for about 10 minutes, until the potatoes and broccoli are tender (stirring occasionally). Stir in the chard and cook for 5 minutes more. Remove from the heat and let stand for 5 minutes.
3. Blend the soup right in the pot using an immersion blender, until the soup is fairly smooth but still has some small chunks. (If you don’t have an immersion blender, ladle batches of the soup into a standard blender and process gently before returning to the pot.) Serve immediately.