Magnification of sun through glass windows can burn foliage. Foliage can also burn fast if you don’t acclimate an indoor plant to outdoor life before exposing it to direct sun rays. You won’t see it right away, but the next day you may find large brown or black spots that look like bruises on your foliage. This is the first sign of foliage burn. The next day, those spots may dry up and turn crispy — very similar to what happens to us when we are burned by the sun. Be sure to pull any foliage that is touching glass away from the window. And if you are to take your plant outdoors during the summer, give them a shady start and at least a week of acclimation before putting them under direct sunrays.