Hardiness zone (n.): A geographic area in which specific plants are able to grow. If a plant’s tag says it is “hardy to zone 10,” then it cannot survive below 40 degrees Fahrenheit. View a zone map to see what zone you live in, and research your plants to find out if they can survive the minimum temperatures in your area. If they cannot, you may overwinter the container plants from your balcony garden to keep them alive. Zones range from Zone 1 (which reaches –50 degrees Fahrenheit) to Zone 10 (a minimum of 30 to 40 degrees Fahrenheit).