What you do with your plants now depends on HOW they return. The zinnias, vincas, and marigolds are all annuals. The plants completely die with first frost, but they have been busily making seeds that are now in the ground. The seed will sprout come spring and fresh plants will return. Therefore, you can pull those plants out and dispose of them. If you want to be perfectly safe, you can harvest seeds from the dead plants and save them to sow come spring. I'd save the zinnias and marigolds, but vinca make so many seeds that it's a virtual guarantee to return on its own.

The crinums are perennial bulbs. The leaves will get zapped by frost, as you have seen. Those, you can trim off for neatness sake, but leave the bulbs alone. I like to buy a bag of Black Kow and spread an inch or two of it around the crinum bulbs in the fall. This feeds the bulbs and they bloom better the next year. After the manure, spread several inches of pinestraw, chopped leaves, or other mulch to protect the bulbs from any untimely cold snaps.

Other plants that you did not name, you can easily look up on the web. If they are classified as "annuals", you can pull them out while saving seed. Perennials, you can cut back and mulch (with a few exceptions like salvias which prefer to stand uncut till spring, when they return from the roots), and if they are classified as "tender perennials", you can mulch them well and hope for them to return. You live in zone 8, so your chances are good for many things. If you happen to have bi-ennials, those come up and make leaves and stalk the first year, then return the second year to bloom, set seed, and die. Treat accordingly.

Vincas will reseed like mad. An old gardener told me to go out in spring and stir the dirt where the vincas grew the year before.

I seldom have reseeded zinnias. I save seed heads of the biggest and prettiest and when the seeds turn black, clean them and store until the weather warms the next year. I treat marigolds the same way. They tend to drop a whole seed head and come up in a clump of tiny seedlings, left to their own devices. I pull most annuals before a killing frost so I don't have to view their dead bodies.

Melampodium will reseed without help, if you have that. Some of the near species petunias will reseed. Salvia coccinea will reseed.

I can't presume to guess what else you didn't think of, but among the perennials, gaillardia seeds can be sprinkled around, as can echinacea.

Anything I'm in doubt, I leave the tops until spring.

Nell

Here is a link that might be useful: Scattering Seeds

I pulled annuals out of my pots and left only what still looked good. They looked so much better afterward. Sometimes you hang on to things too long.