They're the ones with the large pompon-type flowers, but some plants can be as short as twelve inches. The French marigolds consist of the more dwarf varieties, growing to a height of six to twelve inches. Many choices are available, with both single and double flowers. Lemon Gem and Golden Gem are varieties of a species of marigold that produce a profusion of very tiny single flowers on bushy plants. The foliage is very fern-like and is more pleasantly scented than any other marigold.
Marigolds can take lots of heat and full sun.
They like well-drained soil and moist, but not wet, conditions. To keep them blooming all summer, remove spent blossoms. Seeds are easy to plant, bloom almost immediately, and can reseed themselves. These plants have very few pest or disease problems. Spider mites can occur during hot, dry weather, but squirting the foliage with water often can wash them away.