Marigolds take 45 to 50 days to flower after the seeds are planted. Early April is the best month in which to plant marigolds, with flowering occurring in May.
Marigolds prefer growing in six or more hours of sun per day, and those receiving less sun will flower less. Marigolds require little care and maintenance, and they need an inch of water a week for survival. Deadheading is the only pruning a marigold will need. This is done by pinching off the dead blooms to stimulate new flowers to grow. If a marigold is deadheaded often, more new blooms will blossom.