Propagation
Division of the clump in spring or autumn. 

Botanic information
Leaf: The sessile bright green leaves are linear to narrow lanceolate with a tapering acuminate apex. The leaves are arranged in whorls of four along the stems pointing forward.

Flower: The minute double-headed greenish tubulate flower have 4-sepals that are united to form a short tube up to 15mm (⅜in) long with spreading lobes. The petals are absent and the flowers are arranged in an axillary or terminal cluster that appears from late spring to early summer. 

Fruit: The tiny membranous nut is enclosed in the calyx tube and the small seeds are viable but the plant is commonly reproduced vegetatively.