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Growing Seasons
On this page, find information to help you understand your local and regional conditions, including:
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- The United States and Canada’s division into three gardening climate areas.
- Finding the growing season for your garden in your yard.
- How regional differences affect plants that grow in your region.
- Why generalized recommendations seldom produce good gardening results in all areas.
- Special climate regions with year-around or reverse-seasons for gardening.
- Descriptions of regional differences in many geographic locations of North America.
- How to get qualified, expert advice about what grows in your area.
North America’s Three Garden Climate Types
Weather patterns, long-term climate conditions, latitude, and terrain divide our country into three distinctly different types of growing seasons:
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- Cold-winter regions with hard freezes
- Mild-winter regions with occasional frosts and low temperatures
- Reverse-season regions that rarely experiences temperatures cold enough to kill vegetable crops.
Find your locale’s growing season region on this map and learn more about how it affects when you’ll plant and how you’ll care for the plants in your home vegetable garden.
Understanding Your Growing Season
Understanding climate conditions in your region that govern how long vegetables will grow helps you choose techniques to lengthen the growing season and protect your vegetables from heat and cold.
The major factors affecting every vegetable garden are:
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- Minimum low temperature, average temperature, and maximum temperature
- Hours of sunlight during days in the growing season
- Measurable precipitation and humidity during growth
- Duration of optimal warmth
- Microclimates affecting the garden site
Generally, this period during which a gardener can raise vegetables largely depends on the date of the last frost in spring and the first frost in autumn (or winter). These start and end dates define the length of the garden season for most gardens, and is especially true for those in cold-winter climates (typically, USDA Plant Hardiness Zones 1-8).
There are two exceptions, mild-winter climate areas (USDA Plant Hardiness Zones 9-11) and so-called reverse-season regions.
Read more about about the growing season region for your location and garden.
Cold-Winter Climate Regions
Most of North America in the U.S. and Canada are included in the cold-winter growing region. Low wintertime temperatures in these areas kill most annual and frost-tender perennial vegetable plants. Extremely cold areas in the cold-winter region kill even hardy perennials and root-vegetable species unless you give them special care.
Areas with winter cold temperatures below 20°F (–7°C) have easily recognized gardening seasons. They typically begin in spring when soil temperatures rise in spring above 40°F (4°C) and air temperatures exceed 60°F (16°C). They continue through spring and summer, and end in autumn with the coming of the first hard frost. Using some “season extension” techniques adds days to the growing season by starting seeds indoors or using frost protection measures to prolong your vegetables’ lives. These practices are especially important for those who garden in USDA Plant Hardiness Zones 2–5.
Those that grow vegetables in Zones 6 and 7 live in areas that are more ideal for growing vegetables in home gardens. Here, the conventional notion of a cold winter followed by spring planting outdoors and fall harvests is practical for most vegetable plant species that produce fruit, berries and leafy greens. Some tender perennials and all hardy perennial and root vegetables overwinter with simple protection, such as mulching.
Special Climate Regions
Mild-Winter Climate Regions
Gardens located near temperate ocean coasts in the east and west, as we well as those in the southerly states experience what gardeners call “mild-winter climates.” These are marked by occasional frosts—or even occasional short hard-freeze conditions—but they typically remain above 20°F (–7°C). While temperatures in most of these areas are higher in winter than other regions at the same latitude due to their proximity to relatively warm ocean waters, some achieve the same effect due to nearby large lakes.
Along the eastern U.S. seaboard, the warming effect of the Gulf Stream in offshore waters moderates temperatures and climates as far north as Canada’s Maritime provinces. Along the western U.S. and Canada, the Japanese Current and downwelling ocean conditions brings cool northern waters south. It moderates the continental cold air mass, warming Canada’s coastal regions of British Columbia and the U.S. Pacific Northwest.
Both of these dominant ocean currents and the large thermal mass of their surrounding seas regulate temperatures inland for many miles until they are blocked respectively by the Adirondack-Catskill and Sierra-Cascade mountain ranges.
Because of prevailing winds, these moderating effects generally are guided by winds moving from west to east.
Some areas in mild-winter regions may experience very high temperature days. In general, temperatures above 87°F (31°C) may prevent vegetables from setting fruit or cause flower or fruit drop. Temperatures higher than 95°F (35°C) may start to damage the plant tissue of tender vegetables. Gardeners in these hot-climate areas should provide shade protection for their vegetables to avoid sun-scald of fruit and foliage damage.
If your garden is located in one of these areas, USDA Plant Hardiness zones 8, 9 and 10, you may be able to grow vegetables outdoors nearly year-round. Use simple protective techniques to prevent frost damage should unseasonable frosts or freezes occur.
Reverse-Season Climate Regions
Special areas in USDA Plant Hardiness Zones 10 and 11 comprise the last type of garden season region, called “reverse-season regions” or “reverse planting climates.” Summer temperatures here are either dry or humid, but have heat that reaches extremes too high for most cool-season vegetables to set and ripen fruit, but have mild winter temperatures that rarely dip below 30°F (–1°C).
The hottest summer temperatures in this region—found in the Desert Southwest, Texas, Hawaii, and Florida for the U.S. and in the Mediterranean areas of Europe and the northernmost portions of the Southern Hemisphere—may scald fruit or kill some vegetable plants outright, and only shade covers and heavy irrigation permits growth during the times normally used to grow vegetables in other areas of the country.
Like some mild-winter regions in summer, gardeners for many areas of reverse-season regions with daily high temperatures above 87°F (31°C) may wish to use shade protection to extend their growing season in late spring. Temperatures higher than 95°F (35°C) may start to damage the plant tissue of tender vegetables. Shade protection of vegetables helps prevent sun-scald of fruit and foliage damage and adds weeks to the harvest period.
Fortunately winter temperatures in this region are sufficiently warm to plant gardens once the summer heat has broken, temperatures fall, and gardeners can enjoy vegetables all winter long and into mid-spring. It is this “reverse” planting and harvesting period from normal garden season practices that gives the region its name.
Garden retailers in such regions are well versed in the details of when and what to plant as well as techniques for growing vegetables; consult knowledgeable experts at garden stores, nurseries and local university extensions for information if you live in a reverse-season region.