Wild Birds Unlimited - East Lansing store has a seed delivery every Tuesday. In the summer months buy it in smaller quantities or store it in the refrigerator so it stays fresh.
To test your seeds’ freshness, pinch the seed with your fingernails and see if any oil comes out. The finches use their bills to twist the seed and sip the oil and then drop the shell. If your seed has dried out your feeder will be skipped.
American Goldfinches are also notorious for leaving a tube feeder half full. Don’t just top off a feeder with fresh seed. Empty the older seed (if it's still good) into a different container, fill the bottom of the feeder with new seed and top it off with the older seed. Goldfinches will probably eat down to that certain level again and then you’ll have to repeat the process.
As you know, there are also a lot of plants that attract finches. These birds love to flock to any flowers that form seed heads. If you garden with finches in mind, you get to enjoy them at the feeders and riding the flowers in search of seeds.