You can let them self-sow to grow more plants or collect the seeds and winter sow them. They also spread, sorta like runners, little plants growing near the large plants. I find they multiply easily and always have plenty to share. I like the flower heads after the petals have fallen but deadhead to help control the self sowing.

Snowdrop has been a very good spreader for me too. I intended to cut off all my cottony seedheads to slow their spread this year, but when I got back from vacation this week most of them had split open already. LOL.

I started with just one in a 4 inch pot and after three seasons there is a 2ft diameter patch. They are planted in my "woodland" garden under a very dense crabapple tree with hundreds of other small bulbs, trilliums, canadian ginger, mayapples, epimediums, toad lilies, shooting stars, maidenhair ferns, etc. - all of which later get covered up by large hostas. I call it layering with an attitude :) Anyway, whatever you do - it will work.