Slice off any dead, badly discolored, broken off or otherwise unsightly leaves of your "Blue Chalk" senecio. Sever each leaf at its base or down as close as you can get to the base. Carefully collect all of the cuttings and compost or discard them.
Cut off the stalk of spent flower heads down at the base of the stalk between the fleshy leaves, being careful not to slice into the leaves. Discard or compost the flower stalk.
Reduce the size of the plant, if desired, by digging and dividing and replanting the separate the clumps rather than pruning away large numbers of the leaves as this mars the plant's natural form and creates conditions that lead to disease.