Well, let's start a conversation about this. How big is your parents' yard? What kind of sun/shade situation does it have? Maybe posting some snapshots would help us to help you as well. My first reaction is that weddings have flowers as bouquets and on tables and that you might be well advised not to focus on what is blooming, but rather what will provide an interesting and structured background. Also, that means putting in things that will last and not worrying about exactly when they are in bloom. You should be fine with regard to frost. Think leafiness as much as blossoms. I know its heresy to some, but you can do well at the box stores buying things like hostas and groundcovers and even evergreens. I hope this helps, and really more info would make it easier to help you more!

Try to find some Helianthus maximilliani blooms. They are perennial sunflowers and they bloom at that time and beyond.

ASTERS! Don't forget asters, I'm sure there are plenty of asters that you can purchase.

Right. Asters! Also, caryopteris (Bluebeard) might still be looking good. Possibly sedum.

For right now, work hard on the lawn and pruning the flower beds. A weed-free, neatly edged lawn, and trimmed and mulched flower beds are your best bet at low cost. Then you would only need a few spots of color to make it look professionally beautiful. Truly, focus on the basics; then any color you add will be a focal point so you won't need so much.

Julia

I agree with Juliat cleaning up is the most important step. I have very little in bloom right now. But you'd be surprised at how much nicely edged lawn and mulched beds help.

I got married in a front yard (well a very big front yard.)
As I remember my mother-in-law cleaned up the place a bit, which if your place is overgrown may be enough of a challenge. Then for color she bought potted plants, including some that she hung from hooks in nearby trees.

Large window boxes into which you put 4-5 Mums in flower are an instant flash of color.

We are having my daughter's wedding reception in our back yard on the same weekend. We are about 2 hours north of you in south central Pennsylvania, Zone 6.

I plan to have the beds freshly-mulched and neatly edged. Am trying to stay up with pruning and cutting back my annuals to keep them blooming as long as possible.

A couple of weeks before the wedding I plan to go to a "dig-it-yourself" nursery to dig chrysanthemums which I will plug in the bare spots. For the front porch, I plan to buy the larger chrysanthemums that are offered for sale inexpensively at the grocery stores here.

Is your reception going into the evening hours? Sunset in our area on that date is around 6:40 PM. I am making hanging votives out of 1/2 pint Ball jars and wire and aiming for a total of 100 to hang in the trees.

I am also thinking of making luminaries to light a path from the parking area to the tent.

I do think the single most important thing you can do is have the beds neatly edged and the mulch newly applied. We have rented a power edger in the past and it is well-worth the $60 charge.

I think a reception like this is fun to plan for, although a lot of work!!