Bright and sunny French marigolds add a cheerful touch to a flowerbed or window box. Depending on their size, which ranges from 5 to 18 inches, they work well as a border plant or as a mass planting. As an added benefit, French marigolds are often planted among vegetables, because their pungent scent helps deter beetles, hornworms, whiteflies, aphids and thrips. Marigolds aren't fussy, preferring poor soil and full sun.
Fill a planting tray with good quality commercial potting soil. Scatter a few French marigold seeds over the top of the soil, and sprinkle a ¼-inch layer of potting soil over the top of the seeds.
Dampen the soil lightly with a mister, and set the tray in a sunny window. The seeds should germinate in four or five days, and will be ready to plant outside in another 10 days, as long as there is no danger of freezing.
Prepare a place for the French marigolds in a garden spot that gets full sunlight. Although marigolds will do fine in partial shade, they will thrive and produce more blooms in full sunlight.
Loosen the soil down to about 8 inches with a garden fork or shovel. Remove rocks and weeds, and then work about 2 inches of peat moss into the top of the soil to improve drainage.
Dig a small hole with a trowel and set the French marigold seedling gently in the hole. Water the area carefully with a watering can or a hose attachment set on spray setting.
Keep the French marigolds moist, but don't soak the soil. Pinch the blooms off as soon as they fade to encourage the plants to produce more blooms.