Place the seed in a jar or other container, cover with water and let it stand for 24 hours.
These seeds need a stratification period before the embryo will begin to grow. After they have been soaked, place Japanese black pine seeds in a plastic bag with moist sphagnum moss or perlite and place in the refrigerator for 60 days.
Following scarification and stratification, plant seeds 1/8 inch deep in loose potting soil. Place one seed per pot. Tamp the soil lightly around the seeds. Place the pots in a cold frame or other protected outdoor spot. Cover the pots with a layer of mulch and keep the soil moist but not waterlogged. Germination will generally take one or two months, but it can be longer.
Japanese black pines have a sparse root system and it is best to plant them in their permanent location as soon as possible. Select a spot with full sun and well-drained soil. Plant the seedlings in the soil when they are between 2 and 4 inches tall. Mulch around the plant to prevent weed competition. The soil can be allowed to dry at the surface between watering, but do not let the seedlings become overly dry.