Roots with thickened sections. They are very easy to dig up and split a clump into lots of pieces and grow them on.

Daylillies also set seeds which may not come true to the parent and some varieties grow proliferations, small plants on the flowering stem which can be removed when the stem is brown and dead. The little plant can be put into a pot of compost with a section of the stem cut just above and below the little plantlet.