Country club chic? Ocean formal?? This is when WWSW (what to wear to a summer wedding) turns into WTF!? Weddings can leave you feeling beleaguered enough (bachelor parties in Brazil, Jack and Jill Showers, 4-day-festivities), and so it's no fun to also feel distress when considering what to wear. That should be the easy part. So, when you receive an invitation requesting "garden casual," just ignore the goofy parlance and focus on these few considerations:
1) What is the setting (country club, yacht, beach, indoor venue)?
2) What time of day is the wedding?
Nine times out of ten, reaching for your khaki suit (like the one pictured above) will do the trick. For ease, pair with a white shirt, white pocket square, brown shoes and belt, and then switch the tie up according to the venue. If it's a country club or yacht, go for a bow tie with some color. If the wedding is in a garden (and tuxes aren't required) then try a tie with a floral print. And if you just aren't sure or want to play it safe, pick a dark solid like navy or black - you'll look "city chic" which works in most places.
If the wedding is later in the evening or if it says "formal" anywhere near the dress code (but not black tie) then a darker suit is preferable. Stick was a solid charcoal or black and build from there. Weddings are supposed to be celebrations so use your style to say that you're the guy who doesn't need to start the conga line but you sure as hell will join in if there are a few single bridesmaids who are game.