Plums, like many stone fruits, can readily be propagated by planting their seeds. Plum seeds require an extended cold period of stratification in order to break dormancy. This can be achieved in one of two methods, either by fall planting or cold storage in a refrigerator before spring planting. Not all plum cultivars will come true from seed, so while you will get a young plum tree from seed it may not produce exact replicas of the plum from which the seed was taken.
Harvest fully mature and ripe plums in the summer. Extract the hard seed or pit from the flesh cleaning and scraping off any flesh stuck to the seed.
Plant the seed right after harvest allowing it to be cold stratified in the ground over the first winter. Alternatively, store the seed in a sealed plastic bag in the bottom of the refrigerator for a period pf 90 days and plant into the ground soil in the spring.
Bury the seed into soil that has been tilled up to a depth of at least a foot. Place the seed 2 inches down from the surface of the soil and cover over with the loose soil tamping down lightly to ensure good seed and soil contact.
Water the seed in at planting time and do not let the soil dry out entirely over the winter, supplementing rainfall or snow melt when needed to maintain light to medium soil moisture.
Increase to regular deep watering once every 10 days to two weeks in the spring when green shoots appear. Plum trees mature into fruiting trees in three to five years time and reach peak production at 10 years of age.
Fertilize your plum seedling once per year in the spring after frost with 1/20 of a pound of 10-10-10 fertilizer for every year of the trees age. Water in well after application to settle the fertilizer into the soil.