My plants are about a foot tall now one is 13 inches the other 14.5 . Should I top them to increase my yeild? How much dose the yeild increase by topping?
Topping, as it were, cuts the Apical Dominance aspect in half. That means that the energy ascertained by the fan leaves after topping causes energy from the photosynthesis focus energy on both tops as equal, until they aren't.
Topping will not by itself increase yield. What it will do is spread the canopy to spread yield sideways.