Can you save the zinnias seeds?

Of course you can! When they are ripened, the seed pods will fall off of the plant and you will see them on the ground near the plant. (You can see them on the plant, too, growing in groups of two or three.)

Dry the seed pods on a rack, I use a baking rack for this, in a cool, dark, dry location for at least 48 hours up to one week. I usually test them by squeezing the pod. If it feels like it is not completely dry, I let it sit for another day.

Once they're dry, you can store with other seeds in an airtight container.