When are red eared sliders old enough to procreate?

Red eared sliders mate at the age of 1-3 years ( females ).

Red eared sliders mate at the age of 1 6 years ( males ).

Both Male and Female have to be 6-8 inches.

For the most part this is false. Red ear slider females need to be atleast 6 inches and atleast 3 years old but usually 4 to 5 years old.

Males need to be 5 inches and atleast 2 years old but usually closer to 3 or 4 years old.

So basically unless your turtles are atleast 3 years old then there will be no mating, the male might try but the female will usually not "accept" until she is ready.