The United States Department of Agriculture (USDA) Plant Hardiness Zone Map is an important tool for gardeners and farmers across the country. It guides them in determining which plants are most likely to thrive in a specific location. These zones are based on the average annual minimum winter temperature, divided into 10-degree Fahrenheit zones.
This past year, the USDA updated its Plant Hardiness Zone Map, reflecting significant changes in climate patterns observed over the past years. The new map indicates an average increase of about 2.5°F compared to the 2012 version, and about one quarter-zone warmer than the 1990 map. This shift in hardiness zones is an indicator of the gradual warming trend affecting the United States (and the world) and has implications for what plants can be successfully grown in various regions.
Each hardiness zone is defined by its unique climate conditions, especially the cold tolerance of plants. For instance, a plant labeled as “hardy to zone 5” can survive in regions where the minimum temperature doesn’t typically fall below -20°F to -10°F. With the zones shifting, plants that were once unable to survive the colder temperatures of a particular area may now thrive there. Conversely, some plants adapted to colder, more rigorous climates may struggle as their local environments become warmer.
The revision of the USDA’s map is a significant change that gardeners and growers must pay attention to. The warmer zones mean that the growing season is extending in many parts of the country. This could potentially allow for a wider variety of crops and ornamental plants to be grown in areas where they couldn’t before. For instance, certain varieties of fruit trees or perennial flowers, previously limited to the Southern states, might now be viable options further North.
However, this shift also comes with challenges. Changing climate conditions can lead to increased pest issues, new diseases, and even the necessity for different soil management techniques. Gardeners and farmers may need to think carefully about their planting strategies, including the types of plants they grow and the timing of their planting and harvesting.
The USDA’s updated Plant Hardiness Zone Map reflects our changing climate and its impact on our environment. It reminds us that as the world around us changes, so too must our practices. Adapting to these challenges can also open up new possibilities for biodiversity and cultivation across the United States. We’d love to chat with you, feel free to swing by The Gathering Garden in Mount Gilead at the corner of W Allenton St and School St, if you want to discuss gardening with us, you can find out more about or workdays on our facebook page.
In these weekly columns, I will share the science of gardening and so many more interesting tidbits. Check back here every week for tailored Montgomery County garden advice, sharing our garden updates, and more.
Let’s grow together!
This article was originally published in the Montgomery Herald and is reused here with permission by Mary Poplin.