Find Your USDA Plant Hardiness Zone
The USDA Plant Hardiness Zone Map shows how cold a region can get during winter. You can search by ZIP code or state to determine your USDA Zone.
Your USDA Zone can help you identify plants that are hardy enough to survive winter conditions in your area, including the first fall frost.
The current USDA Plant Hardiness Zone Map was created in 2012 and is based on averages of the coldest winter temperatures.
Microclimates and Average First Frost Dates
Your yard, or even a specific area within it, may experience frost earlier or later than other places nearby. This is caused by microclimates, which are influenced by factors such as elevation and surrounding landscape.
If you live at the bottom of a hill, slope, or valley, cold air can flow downward and make the area colder than its surroundings. As a result, frost may occur earlier.
Sheltered areas may avoid frost for several weeks longer than exposed areas. When a light frost is predicted, consider the specific conditions in your garden before assuming that all plants will be affected equally.
Plants That Won’t Survive a First Frost Date
Annuals
Most annuals and tender perennials die when exposed to frost. If only a light frost is expected, some plants, such as geraniums and bedding plants, can sometimes be protected by covering them overnight with an old sheet or towel.
Remove the covering when temperatures rise the following day.
Fall mums can also tolerate a light frost but generally cannot withstand a hard freeze.
Container Plantings
Check the hardiness information for plants grown in containers. Plants suited to USDA Zones 9 to 14, including coleus, elephant ears, and begonias, can be moved into a garage or shed before a light frost.
When temperatures become warmer again, move the plants back outdoors.
Houseplants such as philodendrons and tropical ferns can also be damaged when nighttime temperatures fall to approximately 45°F to 50°F. Bring these plants indoors well before the first frost.
Herbs and Summer Vegetables
Many herbs and summer vegetables are sensitive to frost. When a cold snap is approaching, harvest remaining tomatoes, including green tomatoes.
Other tasks include:
- Cutting flowers such as dahlias, zinnias, and marigolds for bouquets
- Making pesto with remaining basil
- Pickling cucumbers
- Harvesting peppers
After harvesting, remove summer garden plants and add them to the compost pile. Removing them before a freeze can make garden cleanup easier.
Cool-season crops such as lettuce and potatoes can remain in the garden somewhat longer, but produce should be harvested before heavy frost reaches 28°F or lower.
Frequently Asked Questions
How reliable are average first frost date predictions?
First frost dates are based on historical averages, but weather is unpredictable. Frost can occur earlier than the predicted date, so it is best to treat the first frost date as an estimate and prepare the garden somewhat in advance.
What's the difference between a light, moderate, and severe freeze?
- Light freeze: 29°F to 32°F; can kill tender plants.
- Moderate freeze: 25°F to 28°F; causes more extensive plant damage.
- Severe freeze: 24°F and below; can kill most plants in the garden.
What if an early frost is suddenly forecast?
If a light frost is predicted, protect vulnerable plants by covering them with a row cover. A bed sheet can also provide temporary protection and help insulate plants from the cold.
