Magellan series might be what you're looking for.

The Magellan series are about 12 inches tall with large flowers about 4 inches across. Dreamland series is about 18 inches with the same size flowers However these are new varieties and the seed is expensive about 15 seeds for $4.95. I like the dwarf Persian carpet around 10 inches tall with rich colors like are found in a Persian carpet with 1 1/2 inch flowers.

If you buy a dwarf variety and study the package for size. If you give them the right growing conditions with full sun--sun all day-- and good soil they shouldn't get leggy.

Hi Linda,

" Looking for recommendations of zinnias that will stay relatively short (between 10 and 15" possibly but not more than 24")? "

As a senior citizen I prefer taller zinnias, because I don't like to stoop or kneel to work with them, so many of my zinnias are 4 to 5 feet tall. But not nearly all of them. Landscaping-wise, the 24-inch plants in your size range might look better. The Burpeeana Giants and the Whirligigs have less-tall plants that might be to your liking, and to your son's liking. And their seeds are more reasonably priced. And crosses between them are easy to make, with interesting results that your son might like to do.

Persian Carpets have interesting color combinations, but their seeds are considerably smaller, and might be a bit difficult for your son to handle. And they are so light-weight that a puff of wind could blow them away.

ZM

Thank you. Our height recommendations are based on the fact that we have llamas and the fencing that will protect the zinnias isn't tall enough for taller ones. The llamas were reaching over last year and nipping them because they were so tall 3 to 4'. I will look into these ideas. Ty again.

I should ask which of these if any are OP or heirloom as he likes keeping the seeds?

Hello Linda,

" I should ask which of these if any are OP or heirloom as he likes keeping the seeds? "

Persian Carpet is an heirloom. I believe that Magellan and Dreamland are F1 hybrids, which makes their seed more expensive. Whirligig and Burpeeana Giants are Open Pollinated. Your son should not hesitate to save seeds from any of those zinnias, including the F1 hybrids. I routinely save seeds from F1 hybrids, and I even make hybrids between my own hybrids. You can get improvements and new zinnias that way. These were some of my "new zinnias".

It is very easy to make your own home hybridized new zinnias, and it can be a lot of fun seeing what new things you can get. There are so many different commercial zinnia varieties already available that the number of possible combinations of crosses you can make is "astronomical". And you can make hybrids between your own hybrids for new unexpected results. Zinnias can be a fun hobby for young and old. They are easy to grow and they grow fast.

ZM