Prune your Sedum in the fall and again if needed in the very early spring to control the size and shape of the plant and to remove dead tissues.
Cut down the entire plant to just an inch or two above the crown after the first killing frost in the late fall or early winter. If growing in a frost-free or non-freeze climate, skip to Step 3.
Prepare the plant for winter in non-freezing climates by pruning in the late fall to remove spent flower heads and prevent seeding. Snip off all of the flower heads down to just above a healthy lead node or lateral. Trim the plant pack as needed in the early spring to keep it within bounds, if needed.
Pull all of the cuttings cleanly from the plant and soil surface so they don't decay in the plant over the winter, creating disease and insect problems.