The USDA has divided the United States into 13 Plant Hardiness Zones, from coldest to warmest. Many factors influence which zone your garden belongs in; elevation and proximity to large bodies of water all play a part.
Planting zones are especially essential when caring for perennial flowers, vegetables, or shrubs that live for more than one season. Certain gardeners known as “zone pushers” experiment with planting outside their zone range in order to see whether a given species can survive.
Why Are Plant Hardiness Zones Important?
Annual minimum winter temperatures determine planting zones and outline the geographic distribution of wild, cultivated, and invasive plants. The USDA uses them for crop insurance standards as well as to set personal garden plans. By knowing your planting zone you can plan and grow a garden more successfully by selecting appropriate vegetables, herbs, fruits, flowers and other plants; estimate when to plant it and anticipate frost or freezes; as well as estimate when frost or killing freezes may strike.
Plants rely on many factors for optimal growth, from soil quality and water usage to sunlight levels and temperatures in their growing region. Weather is just as essential, with temperatures at the average lowest winter temperature determining which hardiness zones a particular plant belongs to – helping gardeners select plants which will thrive locally.
The 2012 USDA Plant Hardiness Zone Map update showed an upward shift of minimum annual temperatures across the U.S. due to climate change; this trend is predicted to accelerate as long as carbon emissions contribute heat-trapping pollution.
As these changes are significant, gardeners must remain informed. Staying abreast of current information when selecting perennials and shrubs for flower beds, trees for hedges or privacy screens and food crops for vegetable gardens is vitally important. A good way to stay current on relevant information is subscribing to local farmers’ newsletters or visiting the website of their extension service.
Even if your planting zone serves as the best guide, it does not guarantee that a plant will flourish in your environment. Microclimates – or small ‘pockets’ that may have different temperatures from their surrounding environments due to water bodies, elevation changes or landmasses like mountains – could also have an influence.
Additionally, one species of plant may be more hardy or sensitive than its general cultivar; scientists often make genetic breakthroughs that make certain varieties more or less hardy than its original species; when this happens, its label will reflect this change.
Where to Find the Current USDA Plant Hardiness Zone Map
The USDA Plant Hardiness Zone Map divides the United States into 13 zones based on average lowest winter temperatures, providing gardeners with useful information that enables them to cultivate various plant varieties in their gardens successfully. Although updated periodically to reflect new climate research findings, gardeners must still take into account factors which may hinder plant growth when making decisions regarding planting areas and varieties.
An unusually cold winter can harm some plants even when temperatures do not dip below their zone threshold, due to gradual chill tolerance loss over the course of winter and failure to meet minimum hardiness temperatures before frost hits.
Of course, soil type, water availability and humidity levels all play a part in how well a plant grows; these variables can all be adjusted to increase the chances of successful gardening.
The USDA began publishing Plant Hardiness Zone Maps in 1960, and their most recent iteration was released for public download online for free in 2012. Furthermore, state, regional, and national versions are also available to print from this website.
Gardeners, nurseries and plant breeders rely heavily on the Plant Hardiness Zone Map as an indispensable resource. Additionally, researchers use it in models to predict how crops will respond to climate changes; its information can also prove invaluable for commercial growers who must make critical decisions regarding growing conditions and risk insurance coverage.
Gardeners can use this map to select plants that will thrive in their region and where to plant them. Most plants sold from nurseries will include an estimate for USDA Plant Hardiness Zone on their label – giving a good idea whether the plant can survive your climate conditions; but be aware that microclimates such as steep elevation changes, bodies of water or urbanization can sometimes create zones within several miles from one another.
How to Research Your Local Plant Hardiness Zone
When planting perennial flowers, trees or shrubs in your garden, it’s essential that you know which zone you live in. The USDA plant hardiness zones provide an easy-to-use tool that will help you determine what plants will thrive in your region based on average winter temperatures and 13 zones (each 10 degrees warmer than the one before it). Many maps display “a” and “b” designations to clarify temperature ranges further.
Search your zip code on the USDA website to quickly discover your growing zone. While hardiness maps provide a general indication, the USDA map offers more accurate results due to taking into account other weather factors like length of frost-free days and summer rainfall.
The USDA hardiness zone map can be inaccurate if you live near the borders between two zones. For instance, Seattle with its mild marine climate is usually classified in zone 8 while Arizona desert cities like Barstow and Tucson fall in zone 10. This is due to how this system relies solely on average lowest winter temperatures without taking other variables into consideration like elevation and proximity to water sources.
However, the zone system can still be useful for many types of plants – especially annual flowers and vegetables that complete their life cycles in one year without needing protection from frost or harsh conditions. You should use it as a guideline but feel free to experiment with plants that fall below or above your zone rating, especially those labeled cultivars (more refined genetic variants of species).
Keep in mind that USDA plant hardiness zones are only intended to serve as a general indication of which plants will flourish in your region. While they’re useful tools, it’s possible that hybrid species could still flourish outside their listed zone due to being created through genetic engineering; such crosses result in plants which can survive temperatures lower than their usual range and thus make for exciting garden additions!
How to Use Plant Hardiness Zones
The USDA plant hardiness zone map is an easy and efficient way to determine which plants can withstand your area’s winter temperatures. The map divides the United States into 13 distinct zones, each representing an average annual minimum temperature range. You can use its interactive features to search your ZIP code or address and zoom into see which zone applies; or download static maps at various resolutions.
Bear in mind that plant hardiness zones are determined based on average winter temperatures and may differ considerably depending on factors like elevation and proximity to bodies of water. Furthermore, USDA hardiness zones do not take humidity levels into account which could play an influential role in winter damage to plants and trees.
Knowing your zone number can help ensure you select suitable species for your area, no matter where or when you shop for plants and seeds. Most nurseries only carry plants suitable for your region so should have plenty of flowers, shrubs and trees that thrive in your climate. When purchasing plants look for the tag tucked under or near the label; its number should indicate what zone number corresponds with it.
Plants with a hardiness zone of ‘b’ tend to be slightly more resilient than their ‘a’ counterparts, meaning they can tolerate temperatures slightly warmer in winter than their ‘a’ counterparts. However, some varieties may have different hardiness zones from their parent species due to genetic mutations which are initially assigned a lower zone number than usual.
As climate change heats up, gardeners need to adapt their planting strategies accordingly. The USDA is shifting plant hardiness zones northward and gardeners must be prepared for some of their favorite plants to not thrive as much in future seasons.
USDA Agricultural Research Service (ARS) Hardiness Zone Map
Specific details regarding the map can be obtained on the USDA site at:
[…] https://homesteadgardener.wordpress.com/2016/02/05/what-are-hardiness-zones/ […]
[…] it’s time to choose what plants you want to grow. Pick plants that are appropriate for your hardiness zone and will stay within the designated vagetable garden area, unless you are planning to apply a spce […]