Marigolds are a member of the Tagetes genus and have large, bulging flowerheads ranging in color from yellow to red. Marigolds grow well in most soils and are excellent flower choices for anyone without a lot of gardening experience. When planning to plant marigolds, it is beneficial to know if the flower is an annual or a perennial so you can be prepared to care for the flower during winter.
Annuals are those plants that complete their life cycle every year, with only a dormant seed remaining at the end of the growing season. Perennials, however, persist over many years, with only the top portion of the plant ever dying back and then regrowing at the start of the next season. There are also a few plants, called biennials, that live for exactly two seasons. Climate conditions can also come into play with certain plants, like how a tomato plant, which is a perennial, is grown as an annual in the North since the roots can't survive through a ground freeze.
Marigolds are annuals, returning to seed at the end of the growing season when temperatures begin to dip. Often, the seeds left behind will begin to grow again the next season, making the flower appear to be perennial, but there is no guarantee this will happen. When growing marigolds, it is best to plant the seeds indoors in March or April and then transfer them to the ground once the frost danger has passed.
There are numerous varieties of marigolds, but most can be broken down into three major groups. The African marigold varieties can grow up to 3 feet tall and have flowers that are 3 1/2 inches across. The French marigold is generally around or under 1 foot tall with flowers that are about 2 inches across. These two groups have been cross-bred to create a third group called the triploids. Triploids can grow a little taller than 1 foot high and have flowers about 2 inches across. Triploids tend to stay in bloom longer than the other varieties, keeping the flower well through the hottest part of the season.
Marigolds have a reputation for being able to repel pests and are often planted on the outside of flower beds for this purpose. While a handful of marigolds will destroy some nematodes, generally there is no real evidence of marigolds repelling most garden pests. Marigolds are also often confused with plants that share the name, like pot marigold and marsh marigold, neither of which is related to the actual marigold. Because of their name, it is natural to think that marigolds come from France and Africa, but actually all marigolds originated in Mexico, Central America and South America.