'Silver King' typically forms a spreading clump of generally erect, non-woody stems to 24 to 36 inches tall and wide. Foliage is aromatic when bruised. Species is also commonly called western mugwort or white sage. This plant is most commonly sold in the US as a cultivar but the Royal Horticultural Society lists the correct name as Artemisia ludoviciana subsp. mexicana var. albula and indicates that Silver King is a common name. By whatever name, it had lovely foliage that provides a great seasonal bridge and is fabulous cut fresh or dried. SILVER KING may spread somewhat aggressively in the garden by rhizomes, though it appears to be more restrained than the species; if you're concerned, try it in containers.
Best grown in poor to moderately fertile, dry to medium moisture, well-drained soils in full sun. Excellent soil drainage is essential for growing this plant and it does poorly in moist to wet soils as plants are susceptible to root rot. Plant stems tend to flop in the summer, if over-fertilized, over-watered, or receive too little sunlight. Prune plants in early spring to tidy, being careful to leave sufficient numbers of live buds on each stem to facilitate bushy growth. Never prune stems to the ground. Foliage may also be lightly sheared in summer to shape, but avoid pruning in fall.