How to Seed Marigolds

Prepare a planting spot where the marigolds will receive a minimum of six to eight hours of bright sunlight per day. Without strong sunlight, marigolds will become weak and spindly. Marigolds prefer average soil, but the soil must be well drained, as marigolds won't tolerate wet soil. To prepare the planting spot, remove rocks, then use a hoe or tiller to loosen the top of the top 8 inches of soil. Rake the soil until it's smooth and level.

Scatter marigold seeds over the surface of the soil, then cover the seeds with a light dusting of soil no more than 1/8 inch thick. Alternatively, create shallow furrows with the corner of your hoe, then plant the seeds in the furrow. Water the planting area using a garden hose and a fine spray nozzle to avoid washing the seeds away. Continue to water the soil regularly and keep the soil evenly moist until the seeds germinate.

Thin the marigold plants when the seedlings are 2 to 4 inches tall. To thin the plants, pull out the weakest seedlings, allowing 6 to 8 inches for smaller varieties and up to 18 inches for larger varieties. Thinning the plants provides adequate air circulation to prevent problems caused by excess moisture.

Water the marigolds during hot, dry weather only, as marigolds are drought-tolerant and do best if the soil is allowed to dry between waterings. Avoid fertilizer, as rich soil produces bushy foliage but fewer flowers.

Deadhead, or pinch off, marigold flowers as soon as they begin to wilt. Deadheading will encourage the plants to continue producing blooms as long as possible. Allowing the spent flowers to remain on the plants will allow the plant to go to seed instead of blooming.