Black-eyed Susans (Rudbeckia) add a dramatic swash of color to summer garden beds, borders and planters. Most varieties have bright yellow blossoms, but red and purple varieties are also available. The upturned flowers have a central black seed cone that earns the plants their name. Seed production prevents the plants from producing a second set of blooms later in the season. Cutting back the black-eyed Susans can reward you with blooms throughout the growing season.
Trim back the flower stems in summer after the blossoms begin to wilt. Cut the stems off ¼ inch above the topmost leaf. Plants that are cut back may flower a second time in the fall.
Cut back the the entire black-eyed Susan plant after the first fall frost kills off any remaining flowers. Prune the stems down to just above the top healthy leaves. Cut off any dead or browned leaves.
Spread a 2- to 4-inch layer of mulch over the black-eyed Susan bed once the ground begins to freeze, typically after three to four fall frosts have occurred. Mulch protects the crown of the trimmed flowers and helps them survive winter.