Place thawed lowbush wild blueberries into the blender cup. Add ¾ cup water, attach the blender lid tightly and blend on high for 10 seconds. Let the blended mix sit for about five minutes to allow the seeds to sink to the bottom of the blender cup.
Pour or scoop out some of the pulp that is floating on top of the mix. Add more clean water and allow the seeds to sink again. Keep repeating this process until you have completely replaced all the wild blueberry pulp and only the seeds remain.
Remove the seeds from the blender cup and spread on a paper towel to dry.
Spread the sphagnum moss along the bottom of the 3-inch box. Sprinkle the seeds along the top of this moss and then cover the seeds with a thin layer of sphagnum moss. Lightly moisten the moss and place the box in a dry area at room temperature (between 60 and 70 degrees). Cover the box with newspaper.
Remove the newspaper when the seeds have germinated, in about a month. Place the box in a sunny location indoors or in a greenhouse. You will need to keep them in this condition until they are 2 to 3 inches tall.
Add peat, sand and topsoil into the pots. Fill each pot with 1/3 of each. Add your seedlings to the pots, one seedling per pot. They should be planted at least 2 inches deep. Keep the seedlings watered and exposed to sunlight for two weeks.
Add liquid fertilizer to the seedlings, at half the strength noted in the directions.
Prepare your planting location with the cultivator or tiller, adding the 10-10-10 fertilizer and mixing into the thoroughly, using a pound of fertilizer per 100 square feet of soil.
Plant your seedlings in the prepared location after all frost dangers have passed.
Add a covering of sawdust or straw to the seedlings for the first winter. When spring arrives and the buds of the lowbush wild blueberry plants have swelled, you can remove the sawdust or straw and fertilize the plants again.