as above, exception being protection from cold at night
, the wind will cause the stems to grow nice n thick n strong
the dome should be clear, so no, the dome wont have caused that.
has the sunshine been long and constant, if not, then your bound to get some stretch. light hours will also cause this to happen. longer night/darkness hours and boom, you have stretch. take the domes off during the day and have them on at night to keep the tempature up. just untill there large enough