Raising Wintergreen from Seeds

I purchased a pack of your wintergreen 'Very Berry' seeds. I live in northeast Pennsylvania, zone 5. When would be a good time to start these seeds? I'm afraid if I plant them now they will come up in the middle of winter. Should I wait until fall? I was going to seed them in a flat and bury it.

Wintergreen seeds are naturally dormant and require a cold treatment to induce germination. In the catalogue we recommend a cold period of 60 days followed by a warm period during which germination will begin. This is what is called artificially breaking the dormancy and variations on this protocol are very common for wild plants or for plants that do not have a long history of cultivation by man. The cold treatment is applied after the seeds are sown by placing the seed box in a fridge for the 60 day period. The key is for the seeds and the surrounding sowing medium to be moist during this cold treatment; if you just put the seeds while still in the packet in the fridge, that does not work. When wintergreen is germinated by artificially breaking seed dormancy the plants can either be transplanted outdoors in late summer or in fall or they can be grown on inside a cool greenhouse or coldframe over winter.
In nature the wintergreen berries appear in summer and drop to the ground by the fall. Over winter the dormancy is broken by the natural cold and by the arrival of spring they are ready to germinate. You can emulate this natural process by sowing the seeds in a flat any time from mid summer to early fall and digging the flat in the ground outdoors so that the surface of the flat is roughly flush with the surrounding area. I would not bury the flat because the seeds are so tiny and could easily fail to germinate because they are covered too deeply in spring. Instead I would apply a mulch to protect the soil surface from drying out until the spring. In spring I would remove the mulch soon after the snow has disappeared and daytime temperatures start to reach 10 degrees Celsius (50 degrees Fahrenheit).