Plant Millennium Flowering Onion bulbs in well-drained soil with full sun to partial shade exposure. Space bulbs 8-10 inches apart. Water regularly during the growing season, ensuring soil remains moist but not waterlogged. Fertilize with a balanced, slow-release fertilizer in early spring. Remove spent flowers to encourage more blooms. Divide clumps every 3-4 years in early spring or fall to maintain plant vigor.