Hello Kristine, happy to help.

Lingonberry plants need acidic soil -- a pH of about 5 -- to produce berries. They will grow in more alkaline soil but they'll only be a nice attractive shrub. My guess is that your soil isn't acidic enough. You can try lowering the pH of the soil around your shrub by applying elemental sulfur but it takes a lot and it needs to be consistently applied to keep it at 5 because your soil will quickly revert to it's accustomed pH if left alone. If you decide to go that route, I would have the soil around the plant tested so that you can get the recommended amount of sulfur to add. Here is a link to the U of MN soil test site where you'll learn about their service and prices. I recommend indicating that you are growing a lingonberry shrub and need information about how to lower the pH to enable the plant to produce fruit.

Good-luck!

The right pH of around 5.0 and planting them in full sun will help them grow more vigorously.

Good-luck!