Marigolds can be grown in all but the coldest climates. They're perfect for the Northeast following the danger of the last frost. They're also easy to grow and have a long flowering period.
There are two common types, the African marigold and the French marigold. African marigolds can grow up to 40 inches (101 centimeter) tall, while French marigolds reach a maximum height of only 16 inches (40 centimeters). Both have rather large flower heads. French marigolds can be up to 2 inches (5 centimeters) in diameter and the African marigolds can be up to 3.5 inches (9 centimeters). There are also color differences between the two. African marigolds only come in shades of yellow and orange. French marigolds, on the other hand, are often multicolored in shades of orange, yellow, mahogany and crimson [source: Garden Guides].
After they've been seeded, marigolds need 45 to 50 days to flower. If this is done in late March or early April they should be ready to plant around May 15. Seeds can be planted in seedbeds or flats. Place seeds on the surface of the soil and then cover with a quarter inch of perlite. The soil should be kept moist and warm. If everything goes as planned your seeds will germinate in just a few days.
When leaves appear on the plants, it's time to transplant them to individual containers. Put them in the shade for a couple days and the plant will become established. When this happens, it's time for full sun. When the last frost has passed, it will be safe to plant your marigolds. It's also possible to sow marigold seeds directly into your garden. The soil should be moist and well drained [source: WVU].
As flower heads become spent, they should be removed. This will allow for continuous flowering throughout the season. The only real downside to marigolds is their fragrance. Some people find it quite unpleasant.
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