Gardening Zones

In 1960, the original USDA zone map was done to show plant hardiness for planting regions.

In 1990, the gardening zones were revised and the maps are recognized as the best indicator of minimum temperatures available.

For example, to use the gardening zones map, find your area, then match its color-coded pattern to the key showing average annual minimum temperature. The key indicates what hardiness zone you live in.

Keep in mind that the map is a general guide; your particular climate conditions may vary. In 2006, the gardening zones were updated by the National Arbor Day Foundation to reflect the warmer climate experienced in many parts of the country since the last revision.

Gardening zones types

There are eleven gardening zones numbered zone 1 through 11. Each zone is 10°F colder or warmer in an average winter than the adjacent area. You will usually find hardiness zone maps in gardening books, magazines, and websites.

Gardening zones help gardeners to compare their climates with the climate where a plant grows well. Climate zone maps were created as tools to show where plants can adapt. For instance, if you want a plant to survive and grow, the plant must tolerate weather conditions in your area, such as average temperature and rainfall.

* In Zone 1, which includes Fairbanks, Alaska and Northwest Territories, Canada, the average annual minimum temperature is below 50.

* In Zone 2, including Prudhoe, Alaska and Manitoba, Canada, the minimum temperature range is -50 to -45 degrees.

* In Zone 3, which covers International Falls, Minnesota and St. Michael, Alaska, the temperature dips down to -35 degrees on average.

* In Zone 4, including Minneapolis/ St. Paul, Minnesota and Lewistown, Montana, the temperature falls to an average -25 degrees.

* In Zone 5, which consists of Des Moines, Iowa and Illinois, the temperature ranges from -20 to -15.

* In Zone 7, which is comprised of areas such as Oklahoma City, Oklahoma and South Boston, Virginia, 0-5 degrees is the average annual minimum temperature range.

* In Zone 8, including areas from Tifton, Georgia to Dallas, Texas, minimum temperatures ranging from 10-15 degrees annually are anticipated.

* In Zone 9, which comprises regions from Houston, Texas to St. Augustine, Florida, can expect a minimum temperature to 25 degrees.

* In Zone 10, including the cities of Naples, Florida to Victorville, California, the average low temperatures are 30 to 35 degrees.

* In Zone 11, which is made up of areas located from Honolulu, Hawaii to Mazatlan, Mexico experience an average annual low temperature above 40 degrees?

What plants to grow

The garden zones you see on plant labels and in seed catalogs are a guideline to choosing plants that will thrive in your particular region. However, cold winter temperatures are not the only threat to a plant's hardiness.

Summer heat, humidity, soil type, and seasonal rainfall patterns can affect the ability of plants to flourish. When it is time to select your garden crops, check the zone number first to help decide what plants to grow. Note that a plant that grows successfully in zones 4 or 5 will not succeed in zone 8- 11.

For an example of a plant to grow in zones 4-11 are cucumbers. In zone 4 and above, choose short-season varieties and use season extension techniques such as cold frames and cloches to keep cold temperatures at bay.

* Growing bush varieties of cucumbers are a good choice for small gardens. They will produce a lot of fruit on a compact plant rather than on the classic sprawling vine.

* Grow cucumbers on a trellis to lessen the chance of plant diseases and increase yields 20 percent.

* Supplying the cucumber plants with organic mulch including crushed eggshells or bone meal provides them with plenty of calcium that keeps the fruits crunchy.

When to plant

Cool season crops such as broccoli and lettuce can be planted as soon as the spring soil can be worked. For veggies that prefer warm weather like eggplant and peppers, wait until the nights no longer dip below 50 degrees. The plants should be hardened off to prepare them for harsher outdoor weather.

If the soil is on the cool side in your gardening zone, soak the seeds of crops like peas in damp paper towels for 1-3 days prior to planting to speed germination. Plant the seedlings after they begin to sprout. Choose a time to plant in the late afternoon or early evening while there is still good sunlight in your gardening zones.

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