July 4th here.
Some plant until the 10th after peas, but that isn't safe. ;)
Reading the question, I first thought when is the earliest to plant beans? But I guess it is the latest.
Anyhow, totally meaningless either way, without a location. Beans respond to daylight hours as well as frost, so it all depends where you are. In a dry summer, I've seen people plant beans the first week of July, and no rain until August, so they first sprouted mid August. That didnt go well of course.
Is anything in farming really safe? We just go with averages, and guess the weather, guess the climate, etc.