One of the easiest if not easiest annual for cutflowers are the Zinnias, especially the Benary's. They take heat and not too much bothers them. They are a cut-and-come-again variety which means when you cut one stem many more will grow and you will have non-stop cutflowers. Pampus Plume Celosia is another one that loves the heat and produces feather-type flowers.

I'm also a beginner, looking for similar, pretty flowers to go in an empty space in a bed. Will these do well in partial sun, next to a very hot brick wall? I'm in NY, zone 7.

One overlooked flower is the sunflower. In modest sizes, of course, that aren't as coarse as the giants. They can last a week in a vase and can grow in conditions that will blast traditional cut flowers into gauntness.

May I know how I can prolong the life of cut flowers both in
a vase or arrangement in a wet oasis sponge.