Hindsight is everything. Like ripping out all the hard wire garden patio lights and putting in some new fancy solar ones, only to realize that those darn things won't charge on the North side or heavy shade areas.
This year's blooper: I hung a bird feeder off the over hang of the garage right beside my calibrachoa hanging basket. It was only of those bell shaped seed suets.
Not only was is super easy access for the squirrels to get too, I also provided them the ultimate chair - The hanging basket. I think one squirrel ate the entire thing in one day. The Basket still looks a little low in the middle. Won't do that again.
Got any gardening bloopers to share?