> Next: Early Starts for Vegetables
Garden Seasons and Climate
On this page, find how your garden site, local conditions, geographic location, and its surroundings affect how vegetables grow, including:
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- Location and other factors that affect how vegetables grow.
- Site conditions, plant hardiness zone, microclimate, and length of season.
- How to observe light, wind, and other conditions that affect your garden and vegetable plants.
- How to plan a successful garden for your location and site.
Climate and Exposure Factors for Vegetable Gardens
A garden’s location, elevation, prevailing winds, sunlight, and site other factors are important for growing vegetables and determining whether the garden’s plants will succeed or fail.
The most productive and successful vegetable gardens exist in harmony with their surroundings, climate, and site.
The U.S. Department of Agriculture (USDA) divides the world into 11 plant hardiness zones. The average lowest temperatures these regions experience during winter determines their USDA hardiness zones [see Planting and Harvest Planner]. Take a few minutes to find your hardiness zone by consulting the USDA maps.
Knowing your plant hardiness zone helps you predict which plants will survive in your yard. The zones also relate indirectly to the length of the growing season and typical last frost dates for your location. Together, they’re a helpful guide for choosing vegetables you’ll be able to grow.
Microclimates: An Important Variable
Microclimates—localized climatic variations—can also affect your vegetable gardening success and your plants’ performance.
Microclimates are very small-scale temperature and growing-condition differences found at a specific site. They make it differ from its surrounding area or region. These differences result from impacts due to surrounding foliage, structures, the lay of the land, and hours of sunlight.
Low areas trap cool air and influence the growth of your plants. Slopes facing the sun make their locations warmer and drier than other nearby areas, while sites facing away from the sun are cooler and moister.
Take note of conditions near walls, fences, trees, and structures in the area of your garden. Also note the amount of sunlight your garden receives during each season, from little sun in winter months to lots of sun during summer. Determine your site’s exposure to prevailing winds that would cool and dry out your plants and garden soil.
Locations that are sheltered and free from strong winds grow the best gardens, as do those facing south for a full-sun exposure in the northern hemisphere or those facing north in the southern hemisphere.
While many vegetables grow successfully to full harvests in locations with as little as 4–6 hours of sunlight daily, only a few vegetable species will thrive with less direct sunlight. Drying winds further reduce their numbers.
When the area you plan to garden is shaded by surrounding trees or buildings, pruning foliage and limbs helps add to the amount of sunlight your vegetables will receive. Painting nearby walls and fences white helps reflects sunlight and heat back into shady areas of the garden, making a significant difference how a vegetable garden’s plants will grow and produce.
Regional Variations
Many regions have characteristics that make them unique gardening locations. Gardens of the deep south and the desert southwestern United States, for instance, may experience high temperatures that limit the plants that will grow there.
In these hot-summer regions, plant in summer for heat-loving vegetables like peppers and melons, but also remember to plant cool-season crops that take advantage of the area’s mild winters.
Another special regional difference is found where winters are mild. Locations such as southern California, Florida, Arizona, parts of Texas, New Mexico and Hawaii also may be suited to autumn or winter plantings because frosts are rare and daytime conditions are warm and sunny.
Choose your site with care and foresight. The right location is likely the most important factor in successful gardening. Once you have determined the proper site, you can plan your garden’s layout.
Earth’s Orbit and the Seasons
We enjoy our four seasons because of a fortunate combination of the earth’s annual orbit around the sun and its tilt—inclination—in the axis of its daily rotation.
The earth’s rotational axis is tilted about 23.4° from the plane of its solar orbit. This progressively exposes different areas of seas and land masses to the sun’s light and heat as the earth moves around the sun.
Two solstices and two equinoxes each year divide the year into the four seasons we all enjoy: familiar spring, summer, autumn, and winter seasons.
The so-called winter solstice is the shortest day of the year in the Northern Hemisphere (but the longest day of the year in the Southern Hemisphere.) This solstice marks respectively a beginning of the winter season or the summer seasons for each hemisphere.
At this winter solstice, the Northern Hemisphere experiences the fewest hours of the sun’s light and heat, and the time elapsed from sunrise to sunset is the shortest of the year. At high latitudes, above 60°N the sun remains below the horizon 24 hours per day.
During the days near the winter solstice, a large part of the sun’s light and heat also reflects off the planet at a shallow angle rather than hitting its land mass straight down on its surface as it would in early summer. This further reduces the amount of heat absorbed by the planet on the winter solstice.
The reverse of all these effects is true in the Southern Hemisphere during the Northern Hemisphere’s winter solstice. For them, it’s the start of summer, overhead sun, long days, and great weather for growing plants.
As the earth’s orbit progresses around the sun from this winter solstice, days grow longer in the Northern Hemisphere and shorter in the Southern Hemisphere, until they reach their respective spring (or autumnal) equinoxes, or maximum (or minimum) sun exposure.
After the equinoxes, the exposure reverses until they return to the winter solstice in the Northern Hemisphere (summer solstice in the Southern Hemisphere.)
Gardeners plan their year around these seasons, produced by our planet’s orbit around the sun and earth’s axial tilt.