'Grapes' in the Bible

He plowed its land and cleared it of stones. Then he planted it with the choicest vines, built a watchtower in the middle of it, and dug a wine vat in it; He expected it to produce good grapes, but it produced only wild ones."

What more could I do in my vineyard, that I haven't already done? When I expected it to produce good grapes, why did it yield wild ones?

For before the harvest, when the season of budding is over, and sour grapes ripen into mature grapes, he cuts off the shoots with pruning knives, clearing away the spreading branches as he lops them off.