Remove the pit from a ripe plum and wash off all fruit flesh
Let the pit dry for a day or two
Crack the hard shell carefully to remove the seed inside, if possible
Place the seed in a damp paper towel or moist peat moss
Seal it in a plastic bag or container
Refrigerate it for 8 to 12 weeks for cold stratification
Check occasionally to keep the medium slightly moist
Plant the seed in a pot with well-draining soil after stratification
Bury the seed about 1 to 2 inches deep
Water lightly after planting
Keep the pot in a warm, bright location
Maintain evenly moist soil, not soggy
Transplant the seedling outdoors after it develops several true leaves
Choose a sunny spot with well-draining soil
Space it far enough from other trees for mature growth