Why hostas go green
I have observed my own small collection of hostas and seen how many lose their variation and turn very green as the season progresses.
The green is obviously chlorophyll which the hostas use in photosynthesis to grow. Hostas of the Plantagenia group do well in sunnier locations because they function with lighter leaves with less chlorophyll. Darker leaved plants do better in shadier locations.
I think when hostas turn green seasonally it is because of a couple of factors. The shade increases as the leaves of trees or other shade becomes denser and the leaves compensate by producing more chlorophyll resulting in greener leaves. The plant is larger needing more chlorophyll and is sending up scapes and producing seeds which takes more energy.
I think the equation goes- light times chlorophyll equals the energy needed for the plant. Give a plant a lot of sun and it cuts back on green to compensate. Give it less sun and it increases the green to compensate. Want more variegation; give it more sun. Want more green, give it more shade. Give it too much sun and it blanches out. Give it too much shade and it turns all green.
???, or is this old news?