Marigolds are a cheerful flower—even the name sounds happy and sunny—so many gardeners, both beginners and pros, turn to them when planning a garden. Fortunately, the marigold is easy to grow: a few pots and some sterile soil are about all it takes to start indoors, or they can be directly sown in the garden when the weather gets warm.
Add water to potting soil in bag to moisten before use. Add only enough to make the soil damp but not wet—mix thoroughly and let sit until soil is moistened uniformly.
Fill 3-inch pots with sterile potting soil. (Alternately, fill seed flats—initially these allow more plants to germinate in a smaller space, but if they are shallow, they require transplanting seedlings to larger pots before transplanting them to the garden.)
Put two or three marigold seeds in the center of each pot and cover very lightly with sifted soil; firm soil over seeds by pressing gently with fingers. Place one seed per inch of flat, in both directions, if using seed flats; cover lightly with soil; firm soil over seeds.
Place pots or flats in a warm place (around 75 degrees Fahrenheit) until seeds germinate—usually in three to five days. Transplant seedlings from flats into larger 3-inch pots as soon as the first true leaves appear.
Set pots under grow lights positioned a few inches above seedlings as soon as they emerge to prevent spindly, elongated stems. Train a fan lightly on seedlings, if possible, to further the sturdy growth of stems. Raise the lights as the plants grow, keeping them just above the plant tops but not so close that they burn.
Transplant the young marigolds to a sunny, well-drained spot in the garden when all danger of frost is past for your climate zone. Marigolds like their roots slightly damp, but not wet.