Why is my marigold not blooming?

Marigolds are heavy bloomers when conditions are right. Top cause of poor flowering: too much nitrogen — marigolds grown in rich compost produce lush leaves but few flowers. Use low-nitrogen soil and switch to a phosphorus-potassium feed. Deadhead (remove spent flowers) every 3–4 days — leaving dead blooms signals the plant to stop producing. Marigolds are also day-length sensitive: African types bloom better in shorter days (October–February in India).