To propagate Armeria, the most common and easiest method is by dividing established clumps in early spring, which involves digging up the plant, separating it into sections with roots attached, and replanting the divisions in new locations; you can also try propagating Armeria from seed, but this method can take longer and may not always produce the exact variety you want. 

Key points about propagating Armeria:

Best time to divide: Early spring before flowering is the ideal time to divide Armeria. 

Division process: Dig up the entire plant carefully. 

Shake off excess soil.  Use your hands or a sharp knife to separate the clump into smaller sections, ensuring each section has roots.  Replant the divisions in prepared soil, spacing them appropriately. 

Other propagation methods (less common):

Seed propagation: Collect seeds from spent flowers in late summer. 

Sow seeds directly in the garden in early spring.  Lightly cover seeds with soil and keep moist until germination.  Thin seedlings once established. 

Cuttings: Take stem cuttings in early summer. 

Dip the cut ends in rooting hormone.  Plant cuttings in a well-draining potting mix and keep humid until roots develop. 

Important considerations:

Soil type: Armeria prefers well-drained, sandy soil.

Sunlight: Plant Armeria in full sun for optimal flowering.

Watering: Water regularly, especially during establishment, but avoid overwatering.