Successful gardening in Arizona requires a deep understanding of the state’s extreme environmental conditions, particularly intense heat and significant water scarcity. The arid climate demands specialized knowledge to select plants that can not only survive but flourish. Traditional gardening practices must be adapted or abandoned in favor of techniques that conserve moisture and tolerate the alkaline soil typical across the region. Cultivating a thriving landscape is possible by choosing species specifically adapted to manage high temperatures and minimal rainfall.
The Foundational Split: Arizona’s Growing Zones
Arizona’s vast landscape is split into two distinct climatic regions that dictate plant selection. While the USDA Hardiness Zone map shows a range from 5b in the mountains to 10b in the hottest deserts, the Sunset Climate Zone system is often more useful as it considers summer heat and rainfall patterns. Low-elevation areas, such as Phoenix and Tucson, fall into the low or subtropical desert (primarily Sunset Zone 13), characterized by extremely high summer temperatures and mild winters. High-elevation areas, including Flagstaff and Prescott, are classified as high country or high desert (often Sunset Zones 1, 2, or 10). These zones experience true four-season weather, with a short growing season and significant winter frost and snow, meaning a plant thriving in the low desert will almost certainly fail in the high country, and vice versa.
Thriving Plants for the Low Desert Landscape
Gardening in the low desert, which includes cities like Phoenix and Mesa, requires a focus on xeriscaping—a style of landscaping that minimizes water usage. Plants must be selected for their ability to tolerate sustained, intense summer heat and alkaline soils. The soil in this region is often low in organic matter, making it challenging for many non-native species.
Shade Trees
Creating shade is a primary goal, and specific trees are adapted to this environment. The Palo Verde is a popular choice for its fast growth and dappled shade, known for its green bark that photosynthesizes when leaves are shed during drought. Mesquite trees, particularly native varieties, are deep-rooted and handle the heat and drought exceptionally well, providing dense shade. A smaller option is the Desert Willow (Chilopsis linearis), which offers excellent heat tolerance and fragrant, trumpet-shaped flowers.
Shrubs and Accent Plants
Flowering shrubs provide color while maintaining low water usage. Texas Sage (Leucophyllum frutescens) is noted for its silvery foliage and purple flowers that bloom after summer rains or high humidity. Yellow Bells (Tecoma stans) or Orange Jubilee (Tecoma x ‘Orange Jubilee’) are vibrant options that produce striking bell-shaped flowers from spring through fall. For a dense screen, the Hopbush (Dodonaea viscosa) is favored for its evergreen nature and ability to tolerate full sun.
Groundcover and Succulents
Groundcovers and succulents are fundamental to the low desert landscape, offering texture. Agave species, with their bold, architectural rosettes, are iconic and highly drought-tolerant, coming in many sizes and colors. Red Yucca (Hesperaloe parviflora) is a favorite for its long, arching leaves and coral-red flower spikes that attract hummingbirds. For low-growing color, the Angelita Daisy (Hymenoxys acaulis) is a perennial that provides sunny yellow blooms year-round.
Gardening in the High Country
The high country environment, found at elevations above 4,000 feet, presents different challenges, primarily focusing on cold hardiness and a significantly shorter growing season. Plants must be able to withstand winter temperatures that drop well below freezing, requiring species adapted for colder climates. Although the soil is often alkaline, the temperature extremes are the main limiting factor.
Trees for Cold Climates
Deciduous trees that require a winter chilling period thrive here, unlike in the low desert. Aspen trees (Populus tremuloides) are a favorite for their bright yellow fall color and ability to handle the cold. Conifers like various Spruce species are well-suited to the mountain environment and provide year-round greenery. The cold season is a benefit, allowing for the growth of many temperate-climate trees.
Shrubs and Perennials
Cold-hardy shrubs and perennials are necessary for structure and color in the high country. Lilacs are a common choice for their fragrant spring blooms. Flowering shrubs include Forsythias and the durable Wintergem Boxwood (Buxus microphylla japonica), which holds its bright green foliage throughout the cold months. Perennials like Penstemon are adapted to the mountain climate, offering consistent color during the short growing season.
Growing Edibles in Arizona
Food production in Arizona is highly dependent on seasonal timing, which varies dramatically between the two main climate zones. Unlike temperate regions with a single warm season, the low desert benefits from two main planting seasons: a productive cool-season winter and a challenging warm-season summer. Warm-season crops must be planted early in the spring to mature before intense summer heat causes the pollen to become non-viable.
In the low desert, cool-season vegetables like lettuce, spinach, carrots, and brassicas such as broccoli and cabbage, thrive during the mild winter months (typically planted September through January). The summer season is reserved for highly heat-tolerant crops, including okra, sweet potatoes, long beans, and melons. A significant advantage of the low desert is the ability to grow frost-sensitive fruit trees like citrus and dates.
The high country operates on a shorter, more traditional summer growing season, generally extending from May until the first frost in the fall. Gardeners focus on short-season vegetables that mature quickly, such as lettuce, carrots, and early-maturing tomato varieties. The cold winters are beneficial for growing deciduous fruits like apples, peaches, and cherries, which require chilling hours to produce fruit. Succession planting of cool-season crops in the spring and fall helps maximize the harvest in the limited window.