As an added bonus, I got to harvest a lot of marigold seeds for next season. I originally ordered aprox. 200 seeds, and ended up with way more than I had. Here's how I harvested them!
1. Wait for the flower heads to dry all the way into the stem. This will ensure that all the seeds have matured and have had a chance to dry a bit.. you can see how the stem is brown, and it was physically hard when this flower was removed
2. Cut the flower heads off and collect them in a container
3. Remove all of the pedals from the flower head. I also remove as much of the yellow chaff-like stuff from the head of the flower by rubbing it against my palm
4. Peel a bit of the hard shell of the side, and the seeds will be easily removed
5. Save them for next year! I'll be keeping mine in a plastic bag inside of the refrigerator
There you have it! Super, super easy and a great way to take your initial seed investment and keep it going for years on end. Happy harvesting!