To propagate Rudbeckia (black-eyed Susan), the most reliable method is by division, which is best done in early spring when new growth appears, by lifting the plant and carefully separating sections with roots to plant in a new location; you can also propagate Rudbeckia by sowing seeds in early spring or fall, though this may take longer to establish a mature plant;. 

Key points about propagating Rudbeckia:

Division: Considered the easiest and most effective method. 

Best time to divide: Early spring or fall when the plant is actively growing. 

Divide: Use a sharp spade to carefully cut sections of the plant with roots attached. 

Plant: Replant the divided sections in a new location and water well. 

Seed Propagation: Sow seeds directly in the ground in early spring or late fall. 

For earlier blooms, start seeds indoors in late winter or early spring.  May need to stratify seeds (expose them to cold temperatures) for a period before planting.  Lightly cover seeds with soil and keep moist until germination. 

Important considerations:

Check your variety: Some varieties of Rudbeckia may be more easily propagated by division than others. 

Plant spacing: When dividing, ensure adequate space between new plants to prevent overcrowding. 

Watering: Keep newly planted divisions well-watered until established.