The United States Department of Agriculture (USDA) uses winter low temperatures to determine the appropriateness of certain plants for specific regions in the country. This hardiness map has been a standard for gardeners for many years. However, how well a particular plant does in USDA zone 5 is due to a number of factors of which minimal winter low temperatures are just one. Using a climate map from Sunset Magazine can give you more solid information on planting in your region within USDA's zone 5.
Sunset's Climate Zone
Sunset's climate zone map takes a more specific approach to defining growing zones than the USDA does. This means that there are more specific growing region in the Untied States and less general regions. While the USDA map shows where plants will survive through the winter, the Sunset map shows where plants will survive year round. Such things as wind, ocean influence, summer heat, rainfall, humidity, microclimates, continental air influence and elevation all play a critical role with regards to a plant's ability to grow.
Adapt USDA Zone 5 to Sunset
USDA growing zone 5 translates to Sunset's zones 1A -2B and A2.
This zone includes the coldest mountain areas in the United States. The growing season is remarkably short, only 50 to 100 days, with relatively warm summer temperatures. This zone includes the coldest region of the Rockies, apart from Alaska. During the growing season, the days are mild and the nights are chilly, which helps to prolong the flowering time of perennials. Reliable snow serves as an insulator for plants. Short-season, warm season vegetables will also grow well here. Winter lows range from 1 to 11 F with extreme lows to -50 F.
A growing season of 100 to 150 days in possible in this zone, which begins in Colorado's northeastern plains and takes in areas of Western Montana, Nevada and the mountains in the Southwest. This area is the coldest zone in which apples and sweet cherries will grow. Winter temperatures are generally between 10 and 20 F but can dip to -20 to -30 occasionally.
Winters are frosty and summers are long and warm in this region, which makes it ideal for growing fruit. Colorado's Western Slope and mild parts of the Front Range fall into this zone. Reno and Lovelock, Nevada, as well as large areas of New Mexico and Arizona, are also included in this zone. Winter lows hover somewhere between 12 to 22 F and the growing season runs for 115 to 160 days.
Popular Plants for Zones 1A - 2B
Choose from a wide variety of perennials, annuals, herbs, shrubs and trees that don't mind the short growing season or the cooler temperatures.
- Anise hyssop is a beautiful lavender fragrant flower that is easy to grow from seed.
- Basil is a culinary delight, and the annual herb belongs to the mint family.
- California poppy is an upright, compact annual that is native to the Southwest.
- Forget-me-not will grow in full sun or full shade and has lovely soft blue compact flowers.
- Purple coneflower draws butterflies. This drought tolerant perennial also known as Echinacea.
- Spearmint is beautiful and fragrant planted in a container or a hanging basket.
- Tussock bellflower is a dainty low-growing wildflower that is a lovely addition to rock gardens.
- Twinflower is a shrubby creeping evergreen with small pink flowers.
- Woolly thyme is often used as a low maintenance groundcover or in between stepping stones.
Parts of Anchorage and Cook Inlet in Alaska make up zone A2. Winter lows are on average 6 F but can drop down as low as -20 F. The summer days are cloudy and hover in the mid to high 60s, with the occasional 70 degree day. The growing season is between 105 and 138 days. Gardeners do best to start seeds indoors in this region. There are many microclimates in Anchorage; in some places, it can be almost 10 degrees warmer, making plant growing much easier.
Popular plants for zone A2 are bright and beautiful.
- Cosmos is a bright daisy-like flower that will bloom until frost and may re-seed for the following season.
- Wolly Yarrow has fern-like leaves with matted yellow flowers that make this plant perfect for rock gardens.
- Azalea 'White Lights' is clear white. Highly fragrant flowers adorn this shrub that will reach 5 feet in height.
- Viola's flower colors vary, although the most common is violet. This plant has heart-shaped leaves are often heart-shaped.
- Wormwood is a highly fragrant foliage plant that tolerates some foot traffic and shimmers in the sun.
Use Native Species
Keep in mind that when you garden with native species, you stand a much better chance that plants will survive. They are accustomed to the weather and all of the factors that affect a particular zone. Native species are a safe bet for any gardener who is interested in a thriving garden in USDA zone 5 and corresponding Sunset zones.