Why is Hardiness Zone important?
Why is it important for gardeners to know their hardiness zones? Knowing your zone is the key to choosing plants that can survive and thrive in your particular area. Choosing plants that are not hardy in your zone can lead to frustration, disappointment and unnecessary expense.
What determines plant hardiness?
Thus a plant's ability to tolerate cold, heat, drought, flooding, or wind are typically considered measurements of hardiness. Hardiness of plants is defined by their native extent's geographic location: longitude, latitude and elevation. These attributes are often simplified to a hardiness zone.
Where is Zone 4 in the United States?
Zone 4: -30 to -20°F Zone 4 plants can withstand minimum chilled temps from -30 to -20°F. You can find this zone in Montana, Wyoming, North Dakota, South Dakota, Minnesota, Wisconsin, and Eastern states such as Northern New York, New Hampshire, and Maine.
How do you read planting zones?
The lower the number is, the lower the temperatures in that zone. Each zone represents ten degrees of temperature difference. Each zone is also divided into “a” and “b” segments. These represent five degrees of temperature difference.
What is the lowest temperature a plant can survive?
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation. Severe or hard freeze - 25° Fahrenheit and colder causes heavy damage to most plants.
What is the coldest hardiness zone?
Zone 1Zone 1 is the coldest and Zone 11 has the warmest winter temperatures. A plant listed as hardy in Zone 4 indicates it should survive winter temperatures as low as 30 degrees below zero F., which is the average minimum winter temperature according to the USDA map. A Zone 9 plant is hardy only to 20 degrees F.
Where is Zone 5 in the United States?
Where Is USDA Zone 5? Zone 5 starts in the Northeastern United States (including parts of New England, like Maine and New Hampshire, and mid-Atlantic states like New York, Pennsylvania, and West Virginia). It extends across the northern part of the Central US (including Minnesota, Iowa, Nebraska, and Wisconsin).
Where is zone 6 in the United States?
It stretches south and west through Ohio, Kentucky, Kansas, and even parts of New Mexico and Arizona before turning northwest up through Utah and Nevada, ending in Washington state. If you live in zone 6, you may be scoffing at the idea of lows like this because you're used to warmer or colder temperatures.
Where is Zone 7 in the US?
USDA Zone 7 The zone includes Long Island, coastal New Jersey, eastern Maryland, most of Virginia and North Carolina, western South Carolina, southern Tennessee, the northern halves of Georgia, Alabama and Mississippi and much of Arkansas.
Where is Zone 3 in the United States?
Copied! There are 13 hardiness zones in the United States....Zone 3 States.AlaskaColoradoIdahoMaineMinnesotaMontanaNew HampshireNew YorkNorth DakotaSouth DakotaVermontWisconsinWyoming
Where is zone 8 in the US?
In North America, Zone 8 is one of the warmest zones, containing much of the southern quarter of the United States, including much of North Carolina, South Carolina, Georgia, Alabama, Mississippi, Florida, Louisiana, Arkansas, Texas, Arizona, California, and coastal Oregon and Washington.
What zone is Florida?
The Department of Agriculture has designated four zones in Florida--8, 9, 10, and 11. The USDA hardiness zones are based on the average lowest temperatures, helping you choose plants that can survive the winter. Use the zones as a guide for selecting the plants best suited for your area.
What does it mean by hardiness?
Definition of 'hardiness' a. physical endurance; strength. b. hardihood; boldness. Synonyms of.
What is meant by hardiness?
/ˈhɑːr.di.nəs/ the ability to bear extreme conditions or difficult situations: He credits his hardiness to his childhood in the small farming community where he grew up.
Why are some plants frost resistant?
The seeds, and some other tissues, of many plants have very low water contents in their dormant state. They may be anhydrobiotic or the little water that is present cannot freeze. They can thus survive to very low temperatures since there is no freezable water.
What does Hardy H4 mean?
Hardy in coastal / mild areas except in hard winters and at risk from sudden (early) frosts. May be hardy elsewhere with wall shelter or good microclimate. Can survive with artificial winter protection. H4.
What Do Hardiness Zones Mean?
Department of Agriculture. It divides North America into eleven zones by minimum average annual temperatures. The lower the number is , the lower the temperatures in that zone.
What are the limitations of the USDA Zones?
If you live in this area, you may want to use the Sunset climate zones. This system uses more than just the minimum temperatures to determine which plants grow best where. They also use the length of the growing season, summer temperatures, wind, humidity, and rainfall.
What is hardiness in plants?
Hardiness refers to how well a plant will survive cold temperatures. Where the USDA zones fall short, however, is that they don’t account for other factors. These include freeze dates, freeze-thaw cycles, the effects of snow cover, precipitation, and elevation.
What is a USDA zone?
If you are new to gardening, you may be confused by some of the terminology associated with plants. For instance, a USDA zone explanation may be necessary. This is a useful system for determining what plants will survive and grow in certain areas of North America.
How many degrees of temperature difference are there in each zone?
The lower the number is, the lower the temperatures in that zone. Each zone represents ten degrees of temperature difference. Each zone is also divided into “a” and “b” segments. These represent five degrees of temperature difference.
Is there a zoning system for my garden?
No zoning system is perfect and even within your own garden you may have important microclimates that impact how plants grow. Use the USDA or Sunset zones as a guide and always check them to give you the best chance of success in your garden. Printer Friendly Version. This article was last updated on 11/05/19.
Do annuals need zones?
The zones are not important for annuals since these are plants you would only expect to survive the summer months, or one season. For perennials, trees, and shrubs though, be sure to check the USDA zones before you put them in your garden. The limitations of the USDA zones are most felt in the western U.S. If you live in this area, you may want ...
What zone is Puerto Rico in?
In 2012 the USDA updated their plant hardiness map based on 1976–2005 weather data, using a longer period of data to smooth out year-to-year weather fluctuations. Two new zones (12 and 13) were added to better define and improve information sharing on tropical and semitropical plants, they also appear on the maps of Hawaii and Puerto Rico. There is a very small spot east of San Juan, Puerto Rico that includes the airport in coastal Carolina, where the mean minimum is 67 degrees F (19 C), which is classified as hardiness Zone 13b, the highest category, with temperatures rarely below 65 °F (18 °C). The map has a higher resolution than previous ones, and is able to show local variations due to things such as elevation or large bodies of water. Many zone boundaries were changed as a result of the more recent data, as well as new mapping methods and additional information gathered. Many areas were a half zone warmer than the previous 1990 map. The 2012 map was created digitally for the internet, and includes a ZIP Code zone finder and an interactive map.
What is the temperature scale used to define USDA hardiness zones?
Temperature scale used to define USDA hardiness zones. These are annual extreme minima (an area is assigned to a zone by taking the lowest temperature recorded there in a given year). As shown, the USDA uses a GIS dataset averaged over 1976 to 2005 for its United States maps.
What is hardiness zone?
A hardiness zone is a geographic area defined to encompass a certain range of climatic conditions relevant to plant growth and survival. The original and most widely used system, developed by the United States Department of Agriculture (USDA) as a rough guide for landscaping and gardening, defines 13 zones by annual extreme minimum temperature.
What is the minimum temperature a plant can withstand?
For example, a plant may be described as "hardy to zone 10": this means that the plant can withstand a minimum temperature of 30 °F (−1.1 °C) to 40 °F (4.4 °C).
How hot is the Australian zone?
The zones are defined by steps of 5 degrees Celsius, from −15–−10 °C for zone 1 to 15–20 °C for zone 7. They are numerically about 6 lower than the USDA system.
When did Arbor Day update hardiness zones?
In 2006, the Arbor Day Foundation released an update of U.S. hardiness zones, using mostly the same data as the AHS. It revised hardiness zones, reflecting generally warmer recent temperatures in many parts of the country, and appeared similar to the AHS 2003 draft.
Does Canada have a hardiness zone?
For practical purposes, Canada has adopted the American hardiness zone classification system. The 1990 version of the USDA Plant Hardiness Zone Map included Canada and Mexico, but they were removed with the 2012 update to focus on the United States and Puerto Rico. The Canadian government publishes both Canadian and USDA-style zone maps.
Why do I need to know my zone for zucchini?
For annual flowers such as petunias and vegetables such as zucchini, you don't need to pay attention to hardiness zones because these plants usually complete their life cycle (seed sprouting to seed producing) in a single year. You might see these plants given a zone rating of 0 to indicate they aren't hardy anywhere. But when you're dealing with perennials, vines, shrubs, and trees that typically live for many years, you'll want to find out the coldest temperatures a species is expected to survive and compare that to the zone you're in.
What is the temperature of Zone 3?
Zone 3: -40 to -30°F. Most plants native to the U.S. are found within Zones 3 to 10; the toughest of plants can withstand all of these zones. Zone 3 plants can withstand cold temperatures of -40 to -30°F. The upper Midwest states hold most of Zone 3, such as northern parts of Montana, North Dakota, Minnesota, Wisconsin, and Maine.
What is the freezing temperature in Zone 1?
Still, Zone 1 plants can withstand some of the most frigid conditions, because winter temperatures in this Zone can fall below -50°F.
How does the USDA map affect plants?
Although factors other than temperature affect a plant's ability to survive in a particular climate, the USDA map is a good starting point when you're trying to decide what to grow, especially if you live in the eastern half of the country. That's because this area is comparatively flat, so mapping is mostly a matter of drawing lines approximately parallel to the Gulf Coast every 120 miles or so as you move north. The lines tilt northeast as they approach the Eastern Seaboard. They also demarcate the special climates formed by the Great Lakes and by the Appalachian mountain ranges. But in other areas of the country, elevation and precipitation can have more of an effect on plant survival than just temperature.
What temperature can a plant survive in Zone 4?
Zone 4 plants can withstand minimum chilled temps from -30 to -20°F. You can find this zone in Montana, Wyoming, North Dakota, South Dakota, Minnesota, Wisconsin, and Eastern states such as Northern New York, New Hampshire, and Maine.
What is the temperature range for a plant in Zone 7?
Winters only occasionally hit the negatives in this zone. Plants in Zone 7 can handle temperatures of 0 to 10°F. You can find this zone in upper parts of the West (Washington, Oregon) and down through upper Texas, Oklahoma, and all the way through Virginia and North Carolina.
What is Zone 2 in Minnesota?
Again, Zone 2 mostly refers to areas in Alaska, including cities such as Prudhoe Bay and Unalakleet. However, the northernmost tip of Minnesota also falls in Zone 2b, so if you live in or near Pinecreek, you'll want to look for plants that are hardy in Zone 2. Temperatures in Zone 2 can average -40 to -50°F in the winter.
What are Plant Hardiness Zones?
The USDA Plant Hardiness Zone Map was devised by the United States Department of Agriculture (USDA). It was published to help gardeners understand the different weather conditions in their specific area.
What Do The Plant Hardiness Zones Mean?
Simply put, the plant hardiness zone map is a guide that tells you which plants are most likely to survive the winter climate in your region.
How to Use Your Planting Zone
If you remember the section above on annuals and perennials, you’ll know that some plants (annuals) aren’t meant to last the winter.
What is the USDA plant hardiness zone map?
What the USDA Plant Hardiness Zone Map Says. The USDA plant hardiness zone map is as much a thermometer as it is a map. To make it, the USDA split the nation into 13 primary zones, each one colder than the last by 10 degrees Fahrenheit. Each of these zones is then broken into two subsections to account for an area's more specific microclimates.
How many zones are there in the USDA?
The USDA plant hardiness zone map is as much a thermometer as it is a map. To make it, the USDA split the nation into 13 primary zones, each one colder than the last by 10 degrees Fahrenheit. Each of these zones is then broken into two subsections to account for an area's more specific microclimates.
Why do some plants struggle in the winter?
Some plants that would ordinarily thrive in your hardiness zone may struggle if you live in a microclimate where the soil gets too dry. A dry fall can stress these plants just as they prepare for winter. Humidity is also a factor for some plants, as is the duration of any cold weather.
What is the temperature of a plant in Zone 3?
In zone 3, for example, winter temperatures may dip down to -40 degrees Fahrenheit. A plant rated for zone 4, where the winter temperature usually stays above -30 degrees, simply may not survive the winter if it is planted in zone 3.
Do you need to check hardiness zone ratings?
However, following the advice of the USDA plant hardiness zone map alone doesn't guarantee thriving plants. You'll still need to do a bit more research, especially if you plan to push the envelope and grow a plant in a slightly warmer or colder zone than usual .
Which zone is the coldest?
Each of these zones is then broken into two subsections to account for an area's more specific microclimates. Zone 1 is the coldest zone and covers portions of Alaska where only the toughest plants can survive. Found in Puerto Rico, zone 13 is the furthest south and is the warmest zone. Tropical plants can thrive there.
Do fruit trees need cold weather?
Many fruit trees require a specified number of hours in cold temperatures. If they don't get them, they won't set fruit in the spring. The USDA plant hardiness zones tell you where these plants will get the cold weather they need and where they won't. Image Credit: ablokhin/iStock/GettyImages.
Overview
European hardiness zones
The table below provides USDA hardiness zone data for selected European cities:
USDA zones do not work particularly well in the UK as they are designed for continental climates and subtropical climates. The high latitude, weaker solar intensity, and cooler UK summers must be considered when comparing to US …
United States hardiness zones (USDA scale)
The USDA system was originally developed to aid gardeners and landscapers in the United States.
State-by-state maps, along with an electronic system that allows finding the zone for a particular zip code, can be found at the USDA Agricultural Research Service (USDA-ARS) website.
Australian hardiness zones
The Australian National Botanic Gardens have devised another system keeping with Australian conditions. The zones are defined by steps of 5 degrees Celsius, from −15–−10 °C for zone 1 to 15–20 °C for zone 7. They are numerically about 6 lower than the USDA system. For example, Australian zone 3 is roughly equivalent to USDA zone 9. The higher Australian zone numbers had no US equivalents prior to the 2012 addition by USDA of zones 12 and 13.
Canadian hardiness zones
Climate variables that reflect the capacity and detriments to plant growth are used to develop an index that is mapped to Canada's Plant Hardiness Zones. This index comes from a formula originally developed by Ouellet and Sherk in the mid-1960s.
The formula used is: Y = -67.62 + 1.734X1 + 0.1868X2 + 69.77X3 + 1.256X4+ 0.006119X5 + 22.37X6 - 0.01832X7
Macaronesia
Macaronesia consists of four archipelagos: The Azores, the Canary Islands, Cape Verde and Madeira. At lower altitudes and coastal areas, the Portuguese Azores and Madeira belong to zones 11a/11b and 11b/12a respectively. The Azores range from 9a to 11b and Madeira ranges from 9b to 12a, 9a and 9b found inland on the highest altitudes such as the Mount Pico in the Azores or Pico Ruivo in Madeira. The Spanish Canary Islands hardiness zones range from 8a to 12b dependi…
South Africa
South Africa has five horticultural or climatic zones. The zones are defined by minimum temperature.
Effects of climate change
The USDA map published in 2012 shows that most of the US has become a half zone (2.8 °C or 5 °F) hotter in winter compared to the 1990 release. Research in 2016 suggests that USDA plant hardiness zones will shift even further northward under climate change.