To propagate Galanthus (snowdrops), the most common method is by dividing the clumps of bulbs after they have finished flowering, carefully separating individual bulbs and replanting them in well-drained soil; this is best done in the late spring when the foliage is still green, allowing you to easily identify the bulbs to separate.
Key points about propagating Galanthus:
Best time to divide: After flowering, when the foliage is still green.
Method: Dig up the clump, gently separate the bulbs, and replant them in new locations.
Planting depth: Plant the bulbs at the same depth they were originally growing at.
Alternative propagation (less common): Growing from seed, but this can be tricky as the resulting plants may not be true to the parent variety.