Tall marigolds, tall zinnias, Rocket Snap dragons, cosmos,cleome ...I am sure there are others as well.
Linda C

Sunflowers, cosmos, Cleome, Tithonia, any number of amaranthus, tall feathery celosia, tall nicotiana.....

Lynne

There are some wonderful ageratums about 24"--28" tall but they are *very* hard to find. I grew one called Blue Horizon for years but haven't been able to find it for awhile. They gave blue color with almost no work til well into the fall.

I would recommend the Bishop's Children Dahlias from seed. They are fast to grow and about 36" tall and 14" or a bit larger in diameter. The flowers are gorgeous and there are a lot of them. They are always in the top 1/4 of the plant, so if you have stuff growing in front of them, it's not covering up any flowers. There is one more flower -- 'Primrose Gem' annual Chrysanthemum that blooms all summer and is 24-30" tall. It is a Pale Yellow with ferny foliage and double flowers. It is not photogenic in the least, but in person it is a good solid dependable annual.

Lime

Please consider verbena bonariensis (a.k.a. tall verbena, Brazilian verbena). This was a part of my Ohio Zone 6 garden for many years.

The plant grows about 3-4 feet tall with purple flower clusters. This is a see-through plant - the foliage is sparse. It is very drought tolerant.

The stems are strong and I found it a wonderful companion to help keep tall cosmos upright.

It is a prolific reseeder. The new seedlings don't stray far from the mother plant but as they germinate in the spring you will have a carpet of young plants. If you are willing to spend the time to thin, however, you will be rewarded the rest of the year.

I bought them one year. They were really expensive for annuals--about $5 each. And I didn't get a single seedling the next year. Everyone's garden is different, for sure. I do agree that they are lovely and I really enjoyed them that one year.

Thanks for all the suggestions! I would never have thought of dahlias...I didn t even know they can be grown from seed....

I think I ll try Bishop s children at the back and maybe a shorter dahlia in front..

I like the purple verbena as well...it looks a bit like a lavender?? I ve got a yellow cosmos that would go well with it...

Thanks all!
k