USDA Plant Hardiness Zones: How To Find Your Gardening Zone

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The USDA Hardiness Zone Map is used by nurseries, landscapers and gardeners to determine if a plant will grow well in a specific location. This determination is based on the average annual minimum winter temperature of an area based on temperatures for the past 30 years. The map is divided into 10 degree zones. This map is just a guideline and does not consider variations in temperature during the winter season or summertime temperatures. A couple of unseasonably warm days followed by a cold front may cause the hardiest of plants to suffer.

How To Find Your Gardening Zone

The official 2012 USDA Plant Hardiness Zone Map can be found at the USDA Agricultural Research Service website (Click Here). It’s easy to find your zone:

  • Click the link above, then on the state in which you live. A new window will open with a map for the state you selected.
  • Find your location. The color on the map corresponds to a zone in the Average Annual Extreme Minimum Temperature chart.

Hardiness zones are only one way to determine whether or not a plant will grow successfully in a region. There are other factors that must be considered when selecting plants for the garden. When selecting a plant, take the following into consideration:

  • Shade plants can be damaged by too much winter sunshine.
  • If soil moisture is too low in the fall, plants may suffer moisture stress while going dormant.
  • Plants may be able to tolerate the cold winter temperatures but may be too tender for the summer heat.
  • Some plants may only be able to tolerate the cold for a short period of time.
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A Breakdown Of The Different Hardiness Zones

Zone 1 covers the interior area of Alaska where the annual minimum temperature is below -50 degrees and the growing season is very short. Dwarf Birch and Lapland Rhododendron will survive the harsh winters and flower in summer. Choose perennials that re-seed every year. Sow flower seeds in early spring as soon as the soil can be worked.

Zone 2 covers areas inAlaska that have an annual minimum temperature range between -50 and -40 degrees. Paper Birch and the American Cranberry-bush are hardy in this zone. Sow flower seeds in early spring as soon as the soil can be worked.

Zone 3 covers the northern US from Montana to Michigan and New York to Maine. The annual minimum temperature range is between -40 and -30 degrees. Hardy plants in this zone include Panicle Hydrangea and Common Juniper. Sow flower seeds from April 15 to June 15 and from August 15 to October 1. (For more information on gardening in the Northeast, see Tips For Gardening In The Northeast).

Zone 4 covers fromWyoming toWisconsin and fromVermont toMaine. The annual minimum temperature range is between -30 and -20 degrees. Common Privet and Japanese Yew are hardy in this zone. Sow flower seeds from April 15 to June 15 and from September 1 to October 15.

Zone 5 covers a band along the eastern Idaho down to Colorado and across the central US to Indiana. It also covers from northern Pennsylvania to Maine. The annual minimum temperature range is between -20 and -10 degrees. Flowering Dogwood and the Small-leaf Cotoneaster are hardy in this zone. Sow flower seeds from April 15 to June 15 and from September 1 to October 15.

Zone 6 starts in Eastern Washington and flows south down through Nevada and Utah. It also spans from New Mexico to West Virginia. The annual minimum temperature range is between -10 and 0 degrees. Hardy plants in this zone include American Holly and California Privet. Sow flower seeds from March 15 to May 15 and from September 15 to November 1. (For more information on gardening in the Northwest, see A Guide To Gardening In The Northwest).

Zone 7 is slightly south of zone 6 and follows the same path. The annual minimum temperature range is between 0 and 10 degrees. Bigleaf Maple and Kurume Azalea are hardy in this zone. Sow flower seeds from February 15 to April 15 and from September 15 to November 15.

Zone 8 covers the southern part of the US from Northern Texas to Mississippi up to North Carolina. The annual minimum temperature range is between 10 and 20 degrees. Japanese Pittosporum and Viburnum are hardy in this zone. Sow flower seeds from January 15 to March 1 and from October 1 to December 1. (For more information on gardening in the Southeast, see A Guide To Gardening In The Southeast).

Zone 9 follows the Gulf coast fromSouth Texas to northern and centralFlorida. The annual minimum temperature range is between 20 and 30 degrees. Fuchsias and California Pepper trees are hardy in this zone. Sow flower seeds from January 1 to March 1 and from October 1 to December 1.

Zone 10 is found in the southern tip ofFlorida and inHawaii. The annual minimum temperature range is between 30 and 40 degrees. Bougainvillea and Golden Shower trees are hardy in this zone. Sow flower seeds from January 1 to March 1 and from October 1 to December 1.

Zones 11 through 13 are found inHawaii.

The annual minimum temperature range is above 40 degrees. These zones are considered tropical and any plant that can tolerate warm temperatures year-round will thrive in these conditions. Sow flower seeds from January 1 to March 1 and from October 1 to December 1.

To ensure that plants are well protected in the winter, no matter what zone, look for Hardiness Zone information on plant tags and seed packets to help determine which plants will survive the winter in your area, and provide plants with the right amount of sun, healthy soil and good drainage.

Last Updated: February 8, 2012
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About Coletta Teske Coletta Teske has 25 years' experience in tech journalism, as well as home and gardening topics. She has freelanced for Fortune 500 companies such as Boeing and Microsoft, published more than two dozen computer books for Prima Publishing and Macmillan, and worked as a freelance correspondent for West Hawaii Today. Coletta has been an avid gardener since she was 2 years old. While living in Hawaii, she achieved a lifelong dream of becoming a certified master gardener.

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