For a short period the grass will try to force its way through the darkness, so all its energy will make it seem lush and green, then the lack of light will make it weak, eventually dying a slow painful death.
i move any i come accross, i find if they have to be returned to the same place after a cut, because of lack of space in a garden by the end of the season there is a dead patch!!!
i can move all bar the giant 14fter one client has so have told them i wont mow under it!!!
oh the dreaded trampoline if i had £1 for every time a customer had asked me what was wrong with the grass underneath then i would no longer have to work
i move all i come across its not a problem as there are 2 of us
almost all have very little grass underneath
I would guess that as the trampoline shades the ground under it then this area is wetter and so the grass grows more vigorously. Most trampoline mats do let a certain amount of water through the material but they cut down the amount of light that can pass though.
Our blog has some interesting suggestions for ground cover under a trampoline if grass is not the answer