My Kent Begonias grow SOOO thick and wide, I have ti move then further away from the sides of my front foor (hnaging baskets) I use miracle grow pellets and Miracle Grow "Bllom Burst."
The ones that I put into the ground grow taller than my knee..I am 5"6. So wide that now I only use 4 plants iin my flower bed instead of 8. The Miracle Grow over years make my plants grow "Monster Big."