Wildflower seeds are likely to come back yearly after they have become established in their growing area. To give your wildflowers the best chance of returning, make sure you allow them to reseed. Keeping the flowerbed well nourished is one of the best ways to ensure that your flowers will return yearly.
To make sure you have a good display each year, consider reseeding your garden area. If the wildflower seeds that you have planted include varieties that are not native, you are more likely to have to reseed these species. Make sure you are consistent about how you keep your seeds nourished in all cases.