The purpose in posting is to be helpful, not offending in any way, with just a few common sense and practical ideas.
VENUE -
This event took place in a beautiful garden (Bok Tower Gardens) on a hillside in Lake Wales FL. It is an uphill walk to the main Tower area.
Of course, the attendees are permitted to wear whatever they would like, whether formal or casual, and anything between.
CONDITIONS -
However, the paths are not always level and are paved mainly with loose mulch and dirt.
In addition to this, people were of course being served wine, making it possibly even more difficult to walk eventually.
(I don't advocate drinking any type of alcohol, but perhaps you're there for socializing...)
SOME GOOD, SOME BAD -
Hats or visors are a good idea as are sunglasses during the day in Florida. Flat sandals are o.k. too, but covered flat shoes would be even better.
There are overly tame squirrels at this garden, so closed toe (for the mulch as well) and long pants are probably best, not skirts or short dresses.
BEST & WORST DRESSED -
The gal in the middle has dressed the most appropriately overall with flat sandals, hat, sunglasses and a modest long black dress with a high neck. (Black not a great color for heat though).
The gal to the right in the blue dress 'wins' for worst dressed for the occasion with gold high heeled open toe sandals and a very short dress. Don't fall - or bend over either ...and watch the wind!
BAGS & JEWELRY -
A stylish belt bag would probably be best for hands free walking, hiking and snacking. However, a cross-body or small backpack is not too bad. A shoulder bag is not good for this, nor is a clutch.
Less jewelry is also better in this situation. Again, squirrels that will actually climb up someone hoping to find peanuts. Heaven forbid one gets caught in your dangle earrings or in your hair. And no long necklaces or scarves.
THE REST OF THE OUTFITS -
Only the gal in the center with the long black dress is o.k. The rest have on outfits that are either too short, cut too low, drag on the ground (full of mulch & dirt). This is not to be prude-ish but just practical for an outdoor venue.
Some outfits are also too casual for a slightly 'upscale' event. You are not at the zoo. Something comfortable, understated, but also casually elegant is more in order.
WHAT COULD YOU WEAR INSTEAD?
Perhaps a nice pair of cropped trousers, sleeveless top, small cardigan draped over shoulders or tied at waist (in case it gets cooler in the late afternoon or evening), a waist bag or belt-bag, closed toe tennis shoes or loafers, visor or straw hat, sunglasses and a short thicker chain necklace.
Fabrics could include (since it's Florida) cotton, linen, tencel, lyocel, straw (for the hat), macrame crochet for the bag. Prints or solids. Prints and/or darker colors if you're drinking red wine, lighter colors for white wine.