For a large quantity of blooms to cut, you will probably be better off with annuals than with perennials, especially if you're growing them from seed. I grow mostly perennials and woody plants, but do have a few thoughts for you. Zinnias will grow and bloom quickly, but I find the water turns very smelly after just one day; so if you're going to arrange them the day before the wedding, that's a consideration. Cosmos also grow quickly, make good cut flowers, and should give you masses of blooms in colors ranging from white through pinks to deep red. Snapdragon is another quick grower, blooming in late spring to early summer. I hope someone will chime in with more suggestions for you. If not, perhaps try the Cottage Garden forum - there are lots of very friendly and experienced gardeners there from all over the country ... there's bound to be someone who grows annuals in your climate. Don't forget fillers (like baby's breath, gypsophila) and greens - you can choose from solid or variegated leaves, smooth or rough textures, large & bold leaves or long and narrow, even trailers like ivy, whichever best suits your arrangements and your fancy. A trusted friend to help with the arrangements sounds like a good idea. Have a wonderful time with the preparations and best wishes on your wedding day.

Rather than online for these common plants, I'd try to find a proper nursery where you can go and see what you're buying and talk to staff. Only resort to mail order when you start buying unusual things only available from specialists. Everything you mention is easy but now is not the time to be planting them. Bulbs should be planted in Autumn. Rhizomatous Iris, as opposed to bulb iris, go in in late summer. Deciduous shrubs, like the Forsythia, go in in Autumn or early Spring, if you get hard winters. In places with less cold winters you can plant all through winter. While you are waiting for planting time you can be deciding on the layout of your garden and preparing the soil. None of the things you mention will need routine fertilization. The gardening industry is very good at persuading people this is vital. In open ground planting of perennial plants it rarely is. One tip I would give is to stop thinking in terms of 'flowers'. While the blooms are lovely you need to be thinking in terms of plants. They will be a permanent fixture in your garden and need to be considered year round, not just in spring. The best value shrubs and perennials plants have something to offer even when not in bloom. (Except most spring bulbs. They will disappear after blooming and reappear the following year.)

I'm enjoy seeing what's blooming in others gardens before the "big event" of daylilies. My favorite of yours is the Snowball Bush. That's huge. Mine only got to about 10-12 feet. I trained mine into a multistemed tree, sort of like a Crape Myrtles. They say they are short lived here but I got about 15-20 years out of mine. How old is yours?.........I also like your Columine. It grows for me in places nothing else wants to.........Maryl

The Iris take the prize. I just wish they bloomed later. Right now I'm so busy stuffing another plant into a pot that I don't have time to fully appreciate them.....I smelled one at a nursery the other day that was so fragrant. I forget sometimes just how powerful that scent can be..........Maryl