At my last discussion of these plants, there was more than 20 species of these plants and that was a good few years ago, I know there are many more than that now available all in different colours, flower type and sizes,
To answer your question, there are some Annuals that have multi flowers to the stem BUT the flowers are very small also and you might be thinking large blousy type flowers, when I say Blousy I mean bright / bold and fluffy flowers. this type obviously is very Prone to weather conditions in as much as wet or damp climates render these a disaster unless they are indoor or under shelter.
I would be inclined to do a search on Dave's other forums like plant I D, and there you might see the exact type of Zinnia's you need to suit your planting area.
By the way, having the name of the seed ie : Zinnia ?????? you intend to plant would go a long way to ID IF that type is multi flowering,
Give the I D search a go as I'm sure that is a good starter place. Sorry I'm not any good for your question but we don't grow those here in Scotland at least most don't because the weather batters the softer tender stems and the flowers become waterlogged.
Good luck and fingers crossed for you.
Best Regards. WeeNel.
No...you will get many...at first you may only get one...unless you begin pinching out the center stem when they begin to grow. If starting from seed in the garden..give them time to sprout and grow a bit . In a few weeks you can begin to give them a pinch (pinch or cut out the main stem down to a good set of leaves, just above a node where the leaves appear). This will send a message to the plant to put out new growth...making two stems... You ncan continue to pinch a few more times or let them flower and deadhead the flowers once they begin to show that they are done... Think of it as evertime you cut a stem above a node it will make the plant sprout 2 new stems... by the end of the season you will have a nice bushy blooming Zinnia.. Some of the dwarfs tend to branch... You'll just have to see... Kathy
pix is of one of the taller varieties which I grow, the shorter ones can be much more prolithic with blooms. I've seen some that are totally smothered when in bloom...