Add late-summer color with Allium × 'Cobalt Millenium', a clump-forming ornamental onion with showy, rose-purple flower globes held on sturdy stems above glossy, grass-like foliage.
In your garden, expect a neat mound about 12-15 inches tall with blooms hovering a bit higher, and a mature spread around 10-15 inches. It fits easily into mixed borders, cottage plantings, and small groupings where its spherical umbels stand out without flopping.
Plant it where it gets full sun for the best flowering, though it also performs well in part shade. Provide well-drained soil and avoid consistently wet spots to help prevent bulb issues. Once established, it handles dry to medium moisture and is a dependable performer through summer heat.
After blooming, you can deadhead to keep the clump tidy and reduce unwanted seeding. Like other ornamental alliums, the foliage and stems can have an onion-like scent when bruised. Deer and rabbits tend to avoid it, making it a good choice for gardens with browsing pressure.