Each type of plant has a preferred set of growing conditions and tends to grow where those conditions are suitable. If a seed lands in a spot with the wrong conditions, the plant may start to grow, but will be at a disadvantage to other established species, which usually results in the seedling dying.
Gardeners want to grow a wide selection of plants, and they only have one location to grow them all in. Granted, even in a small garden, some areas are wetter and others drier, and some get more sun than others, but for the most part, each of us has one set of growing conditions, and our selected plants must adapt to them.
Let’s take a closer look at growing zones and how plants adapt to various environmental growing conditions.
Garden Hardiness Zones
Hardiness zones, also known as “gardening zones” and “growing zones,” are a set of numeric designations that identify a narrow set of climatic conditions. Most of these systems are based on the average annual lowest night temperature. So, for example, Zone 5 has a lowest night temperature of minus 20 degrees Fahrenheit.
The original system was developed by the U.S. Department of Agriculture (USDA), which uses averages of the lowest night temperatures. Each zone represents a 10-degree increment (see map, above).
North America has 13 zones, with the lowest number indicating the coldest region. These zones are further divided into 5-degree increments using the letters
