How long does it take to grow a marigold from seed?
Marigolds take around 45 to 50 days to flower after you plant seeds, so seeds sown in early April should flower by May.hen it's time to plant marigold seeds, amend the soil in the area with organic matter, like peat moss or compost. Do this by spreading a 1- to 2-inch layer of organic matter over the surface of the soil, then work the organic matter into the soil with a rake or garden hoe.