What Growing Zone Is Thornton?

Our records indicate the United States Department of Agriculture has given Thornton a growing zone designation of 9b. Sometimes also called the planting or hardiness zone, this zone number gives you an idea of what plants can and cannot grow in Thornton's climate based on the average extreme annual temperature.Our data is based on the latest 2023 USDA maps, which used Thornton's weather data from 1991 - 2020 in their analysis.

map of growing zone 9b (Northern California)map of growing zone 9bLatest CA growing zone map

If you are looking for plants suitable for growing in the Thornton area, head on over to our page on plants that grow well in Thornton, CA.

Worm Composting Kit

Worm Composting Kit

Complete kit for starting your own worm composting system.
Seed Starting Trays

Seed Starting Trays

Perfect for starting seeds indoors before transplanting to your garden.
Rustic Iron Garden Trellis

Rustic Iron Garden Trellis

Sturdy trellis for supporting climbing plants and vines.
Shiitake Mushroom Kit

Shiitake Mushroom Kit

Grow your own delicious shiitake mushrooms at home.
Metal Arbor Trellis

Metal Arbor Trellis

Decorative arbor trellis for climbing plants and garden entrance.
map of growing zone 9b (Northern California)map of growing zone 9bLatest CA growing zone map

The growing zone is a measure of the lowest temperature that a plant can survive based on average lowest year temperatures, helping you to decide what plants would grow best in your particular climate. Since Thornton is in growing zone 9b this means that plants there can survive temperatures as low as 25 to 30 degrees Fahrenheit. Plants for Thornton's climate should be chosen with this in mind, or plants should be moved inside to keep their core temperature in the right range if necessary.

USDA growing zone map of the United States

Some zones may have been changed by the USDA as of 2023. To see if the Thornton area has been affected, refer to this map of half zone changes from the 2012 version of the USDA zones to the 2023 version.

map of usda hardiness zone changes from 2012 to 2023Half zone changes from 2012 to 2023

The updated map shows that over half of the Southeast has warmed by about half a zone. For gardeners, that means you can now grow plants that tolerate a bit more heat and less frost than before. The tan areas reflect this shift. Meanwhile, the white areas had slight temperature changes, but not enough to move them into a new zone. In the Western U.S., a few spots shifted cooler. That’s not due to a colder climate, but because the new map uses a larger dataset, giving a more accurate picture of local conditions. It's important to keep track of these changes when planning your garden!

Hardiness Zone FAQ

Have questions about hardiness zones and what they mean for your garden? Check out our FAQ below for quick answers to common questions about USDA hardiness zones and how they affect plant selection in Thornton, CA.

The USDA hardiness zone is 9b for Thornton. This is sometimes also referred to as the growing or planting zone. These terms are used interchangeably.

Thornton's Growing Zone Details

USDA Growing Zone: 9b

Zip Codes: 95632, 95686

Longitude: -121.4249

Latitude: 38.2309

Lowest Avg Temperatures (F): 25 to 30

Seed Starting Trays

Seed Starting Trays

Perfect for starting seeds indoors before transplanting to your garden.
Brass Watering Can

Brass Watering Can

Elegant brass watering can with classic design and durability.
Reusable Grow Bags

Reusable Grow Bags

Breathable fabric grow bags that promote healthy root growth for your vegetables and fruits.
Steel Hori Hori Weeding Knife

Steel Hori Hori Weeding Knife

Versatile Japanese-style gardening knife for weeding and planting.
Hydroponic Garden Grow Kit

Hydroponic Garden Grow Kit

Grow fresh herbs and vegetables year-round with this indoor hydroponic garden system.

Map of the Thornton Area

All Towns In CA

Steel Hori Hori Weeding Knife

Steel Hori Hori Weeding Knife

Versatile Japanese-style gardening knife for weeding and planting.
Large Greenhouse Kit

Large Greenhouse Kit

Spacious greenhouse for extending your growing season.
Self Watering Plant Pots

Self Watering Plant Pots

Innovative pots that maintain optimal moisture levels.
Hydroponic Garden Grow Kit

Hydroponic Garden Grow Kit

Grow fresh herbs and vegetables year-round with this indoor hydroponic garden system.
Cluck Around Sign

Cluck Around Sign

Whimsical sign for your chicken coop area.

Plants For Other States

Looking for the best plants in a different area of the United States? Click on a button below to find plants that are ideal for that state's temperatures.

Alaska Alabama Arkansas Arizona California Colorado Connecticut Delaware Florida Georgia Hawaii Iowa Idaho Illinois Indiana Kansas Kentucky Louisiana Massachusetts Maryland Maine Michigan Minnesota Missouri Mississippi Montana North Carolina North Dakota Nebraska New Hampshire New Jersey New Mexico Nevada New York Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Virginia Vermont Washington Wisconsin West Virginia Wyoming
Wooden Chicken Coop

Wooden Chicken Coop

Spacious and secure home for your backyard chickens.
Rustic Iron Garden Trellis

Rustic Iron Garden Trellis

Sturdy trellis for supporting climbing plants and vines.
Shiitake Mushroom Kit

Shiitake Mushroom Kit

Grow your own delicious shiitake mushrooms at home.
Self Watering Plant Pots

Self Watering Plant Pots

Innovative pots that maintain optimal moisture levels.
Deluxe Plastic Watering Can

Deluxe Plastic Watering Can

High-capacity watering can with comfortable grip and precise spout.

To see our latest gardening and homesteading projects, you can find us on Facebook, Instagram, and TikTok.