10 Answers

The sun.

Heat and Sun and Light   as when they are growing they are green and not ripe until they are red

   And also lycopene and carotene, as long as the temperature is between 50 and 85 degrees.

They turn red when you look at them,they plush!

Still waiting for mine to turn red,my slicers that is,plenty of red cherry tomatos and my canalopes are looking gooood.

Nude Mexican farmers.

country bumpkin

LMAO!

I have tomatoes coloured green, orange black and yellow as well as red. The sweetest are the variety 'green grape' I recommend them highly.

put them in brown paper bags in dark warm place

How does that human develop white hair ?,  the answer to that question is acquiring time to your life, the same pertains to the red tomato, and tomato starts out with a green color which means it's a young  tomato and as it grows older it starts changing colors in some instances it becomes red however there are a variety of colors that tomatoes have the ability in turning.

How does that human develop white hair ?,  the answer to that question is acquiring time to your life, the same pertains to the red tomato, and tomato starts out with a green color which means it's a young  tomato and as it grows older it starts changing colors in some instances it becomes red however there are a variety of colors that tomatoes have the ability in turning.