Elizabeth,

Some snapdragons are rather tall. Larkspur is, too, although it does not have an extended blooming season. There are a few strains of celosia (for example, Flamingo Feather) that look kind of "spiky". Salvia has vertical shaped flower shoots, although I don't know how well they would do in containers.

MM

What about something grassy like purple majesty millet? It looks so nice and is a nice sturdy plant.
gg

I was going to suggest a grass, too.

Some sunflowers. I seem to recall reading of a dwarf "teddy bear" for example.

Some dahlias. May require some trimming.

Great ideas! I've got seed coming for 'Cramer's Amazon' celosia, which is supposed to be tall and spiky. And I think I will look into grasses. I suppose I could use perennial grasses (although I understand I'm in the wrong forum for that!) and then transplant them out into the garden for the winter.

How about suggestions for particular spiky grasses? The purple millet is a good one--any others?

Thanks!

Someone mentioned Salvias, and I agree. They're the best spiky summer bloomer for my money. Salvia farinacea Victoria gets about 18 inches tall and is a blue blooming machine. It's hybrid sister, Salvia Mystic Spires, is about two feet. It has the same look of Victoria, only taller and wider, and bloomed from spring to frost last summer. Salvia Guaranitica, Black and Blue is bigger yet, blooms from mid summer to frost and has the added attraction of the black calyces. All three are perennial here, but are very easy to start from cuttings in late summer if they're not for you. They'll overwinter in a reasonably freeze free garage or under lights in a basement.

Linaria, verbena hastata, cornflowers, Agrostemma, scarlet flax, alonsoa, stipa tenuissima. angelonia, or try summer bulbs such as babiana, gladioli,(although they are not as long lived in bloom.