Most marigolds are annuals, but a few are perennials. Marigolds self-seed so they may appear to be a perennial when in reality, they are just coming back from seed.
If you stop deadheading in August, you will allow some marigold flowers to finish up their life cycle by going to seed. These seeds develop, dry and drop to the ground. It's entirely possible for the seeds to last through the winter to germinate in spring.
Sow seeds directly into the garden once the soil is warm in the spring. You can start seeds indoors, but they germinate so easily outside that there's really no advantage.
Other flower seeds that will germinate faster include moonflowers, lupins, sweet peas and morning glories. Place the containers in a warm place like on the clothes dryer or top of refrigerator. Smaller seeds such as zinnia and marigolds can be soaked as well.. . . . .364011233883!]0000000000000009783314144913!]
