zonal markings fading on pelargonium
Does anyone know what causes the zonal markings on certain pelargoniums? Mine is about five years old and the brilliant burgundy horseshoe markings started fading/not showing up after the second year. Since then, I have periodically searched for an answer to what promotes the markings with no luck. I had become resigned that it may have been some nursery hoodoo beyond my amateur means and does not take away from my love of the plant. Last month, a few of the leaves began showing the zonal marks again and I am hoping I can find an answer to encouraging the characteristic.