garden glass

noun2

1. •
   (old-fashioned) A cloche (normally bell-shaped glass, used for covering plants).

   • for want of frames or any sort of garden glasses, we often preferve cauliflower plants through the winter in a bed of common earth, covered occasionally with garden mats — 1791
2. •
   A globe of dark-coloured glass, mounted on a pedestal, to reflect surrounding objects; much used as an ornament in gardens in Germany.