When days become shorter in the fall and winter and the weather turns grayer and grayer, it makes sense to move your indoor plants as close as possible to your home’s windows so that they can get the best light possible. However, they shouldn’t be so close they actually touch the glass. Even with insulated glass, enough cold seeps through on a truly cold winter night to damage or even kill any leaves or other plant parts that actually touch the window.
You don’t have to move them far back, though. Air is a fairly poor transmitter of cold, so just a 1-inch (2,5 cm) space between the glass and the plants will keep them from harm.