Batchelor button is a good choice because it can take a light frost, and in many parts of 5b the chances of a frost by mid-October are better than slight. I'd add a mix of double calendula -- the old Pacific Beauty mix would be fine. The flowers are much smaller than sunflowers, but they aren't tiny, they cover some of the color range you're looking for and they're very frost hardy. You don't have to start either of these early. I'd wait to start the batchelor's buttons until summer, so they won't exhaust themselves by October. The calendula seem to bloom and bloom. Plant a goodly number of each. You might think of something like a double feverfew to give you a white filler. They're also cold-hardy.

Orange Cosmos From Backyard Summer 2009 Another orange cosmos In full sun and good rich soil they get very tall and huge, I wish I had a picture of one of them "orange cosmos trees" :) From Backyard Summer 2009 Annual Phlox This year I have whites, and different shades of pink. I originally moved a few plants we found growing along a road (when in season, you will see masses of them near highways). The plants flowered and disappeared..And for a few years now, they reseed and bloom in large clumps From Backyard Summer 2009 From Backyard Spring 2009 Salvia Same thing, reseeds. I recieved one plant at a swap two years ago and since then, my yard is covered in them :) They are nice plants to have, I really like them - and they do live for more that a year it seems. From Backyard Summer 2009 Blanket flower Same story, found a plant growing by a road, moved it to my yard and now I have masses of them. They tolerate draught and lots of sun, and poor soils - but boy do they love good soil. In my rose garden, I have to weed them out so they do not eat the roses! The plant gets big AND the flowers are much larger in diameter From Backyard Summer 2009 I do not have a picture of Alyssum . It likes colder weather, or at least does not like the heat as much. It is very popular in Russia in the summer, so very different climate there! In the cooler months, it grows really well, so I would start seeds around that time. Same goes for Calendulas and the pink and white cosmos, they seem to like less heat Marigolds, I start whenever :) They reseed once they are done Here is a picture of Salvia (perennial) with marigolds From Backyard Spring 2009

I would second the vote for dahlias - they come in wonderful shapes, forms, and colors and they make stunning arrangements. In containers, you could cover them if you have frost and they'll be wonderful - the colors of dahlias are always the best and richest at that time of year. Most of my other annuals are finished by this time - I have asters and mums in the fall (but they aren't annuals) - asters are generally finished in September here in Illinois but some of the mums are still lovely in October til hard frost. You can pick those up at garden centers at this time of year and they could be really nice filler flowers. Don't ignore pretty foliage - you may already have some in your garden in trees or shrubs - in October you might be able to add things like japanese maples. I have a green one that turns beautiful gold in the fall along with the deep crimson red. Do you have theme colors picked for your wedding?

I'm waiting until we get past next week's cold spell for the tender annuals. The hardier ones I've planted already, things like snapdragons, pansies and dianthus can take the chilly weather. You'll be just fine planting at the end of May when it hopefully warms up. :) Think of it this way: The garden centers sell annuals well into June, so a lot of people are planting later and it works out for them.