Zone 5 refers to the USDA Plant Hardiness Zone in which I garden here in Hadley — located in Western Massachusetts. With minimum winter temperatures on the rise, however, this zone designation is now changing! Read on.

Years ago botanists and horticulturists started gathering weather records throughout North America to compile a database to show the average coldest temperatures for each region. These records were condensed into a range of temperatures and transformed into various zones of plant hardiness. There are a total of 11 zones. Maps were then made to show the lines between these temperature zones.

The USDA released an updated map in January 2012 to reflect increasing minimum winter temperatures since the previous map was released in 1990. The new map shows a shift of a minimum of 1/2 zone higher and in many areas a full zone higher in others. This is good news to gardeners meaning many of us can consider planting Zone 6 plants now. However, the downside of warmer temperatures is that insects and pests may also be on the increase.

According to the old map, Hadley’s average annual minimum temperatures had been -20°F to -10°F. So, a plant that is described as “hardy to zone 5″ meant that the plant could withstand a minimum temperature of -20°F. The new map reflects annual minimum temperatures of -10°F to -5°F for Hadley (a true Zone 6).

When you purchase a plant, the plant tag generally will show the coldest plant hardiness zone in which the plant will survive through the winter. Although this is not a guarantee, it is a good starting point.

Gardening in New England is always a challenge. Everyone’s garden is unique and you will need to determine which plants will work in your specific conditions. To give your plants the best possible chance for survival, you must consider your soil type, the amount of rainfall your garden receives, daytime and nighttime temperatures, wind, humidity, heat, location of the planting site, and many other factors. (Gardening is not for the faint of heart!)

Contact Debbie at Gardenscapes to learn more about Zone 5 gardening.