The U.S Hardiness Zones have changed over the years. According to the most recent, updated USDA Hardiness Zones Map published in 2012, one can conclude that the average low temperatures experienced throughout the US have risen since the last time the map was published. This could indicate global warming and the concern it carries.
Why should gardeners pay attention to the zone maps? The map indicates the average low temperatures experienced in a specific geographical area. All plants have a low temperature threshold in which, if crossed, could cause damage to and often death of the plant. Also, some plants require a certain number of chill hours (temperatures below freezing) during a given year. If these plants don't get enough cold weather performance or fruit production can be effected.
If you notice that some of your plants your plants aren't growing or producing as in years past, one reason could be that it has gotten too warm for that specific type of plant.
So, make sure that when you are purchasing a plant, whet6her it be from an online or land-based nursery, that it will grow in your USDA Plant Hardiness Zone.
Here's a link to the USDA Hardiness Zone Map here in Gardenality:
