Fully grown green tomatoes emit a gas known as Ethylene gas. Inside a mature green tomato, two growth hormones change causing the production of the gas. This gas ages the cells of fruit resulting in softening and loss of the green color turning into a red shade.
It is pretty basic to harvest the tomato fruit.Start from the bottom of the tomato plant where the plants begin to ripenLightly squeeze the fruits to test the firmnessIf you notice the first bloom of red appearing on the skin, harvest the fruitGrasp the fruit firmly but gently and pull from the plant. ...
Although it is tempting to leave the fruit on the plant in order to enjoy the ripe vine tomato, there are risks attached to that. Most gardeners have experienced that moment when they waited a day longer and regretted doing so.