Arizona Planting Guide: What to Grow and When

Arizona gardeners face a reality that most American gardening guides completely ignore: the state does not have one growing season — it has two in the low desert, and they operate on an inverted calendar compared to every northern state in the country. The same Phoenix gardener who is harvesting tomatoes in June is resting their garden beds in August. The Flagstaff gardener, meanwhile, is working with a single compressed growing season between late May and September, barely different from a gardener in Minnesota.

This Arizona planting guide covers all three major growing regions of the state — the low desert, the intermediate desert, and the high desert and mountains — with specific frost dates by city, a month-by-month planting calendar, and the plants that reliably perform in Arizona’s unique climate. Whether you’re gardening in Phoenix’s year-round warmth or working around Flagstaff’s short summer window, the framework here gives you the timing and plant selection to make your garden genuinely productive.

The single most important concept for new Arizona gardeners is that the low desert is not a hot version of a normal garden — it is a desert ecosystem where summer temperatures routinely exceed 110°F in Phoenix and the soil surface can reach 140°F in direct sun. Understanding which seasons are productive and which require rest or heat management is the foundation of everything else in Arizona gardening.

Arizona’s Climate Zones: Know Your Region First

Arizona spans USDA hardiness zones 5a through 12a — one of the widest ranges of any state in the US. Before any planting decision, your zone determines which crops are realistic and which months represent your productive seasons.

Three pre-planned garden beds, free

Stop staring at empty beds: printable plans with exact layouts, plant lists and planting calendars — yours free from the Garden Library.

Send me the plans

I agree to receive emails from Blooming Expert and accept the Privacy Policy. Unsubscribe anytime.

Three distinct gardening regions define Arizona’s growing conditions:

• Low Desert (below 2,000 feet elevation) — Phoenix, Scottsdale, Mesa, Tucson, Yuma, Casa Grande — Zones 9b–11. Near-frost-free winters, brutal summers exceeding 110°F, and two distinct productive seasons: spring (February–May) and fall (September–November).
• Intermediate Desert (2,000–4,500 feet elevation) — Wickenburg, Prescott Valley, Sedona, Verde Valley, Benson — Zones 7b–9a. Cold snaps in winter, hot summers with moderated extremes, and a single spring growing season extended by a mild fall window.
• High Desert and Mountains (above 4,500 feet elevation) — Prescott, Flagstaff, Show Low, Payson — Zones 5b–7b. True cold winters, cool summers, late spring frosts into May and June, and a compressed single growing season of 90–140 days that demands fast-maturing varieties and precise timing.

The elevation difference between regions is dramatic: Phoenix sits at 1,100 feet while Flagstaff is at 6,900 feet, a difference that translates to roughly 20°F cooler summer temperatures and last frost dates separated by more than four months. Understanding how climate zones affect plant selection and seasonal timing is the foundation of any productive Arizona garden plan.

Arizona Frost Dates by City

Last spring frost and first fall frost dates define your outdoor planting windows for frost-sensitive crops. University of Arizona Cooperative Extension data provides historical frost probability for locations across the state; the table below uses average 50% probability dates for planning purposes.

Source: University of Arizona Cooperative Extension historical frost probability data. Dates indicate 50% probability. For frost-sensitive transplants, use as a minimum and monitor your 10-day forecast.

A critical planning note for Flagstaff gardeners: with only 90–105 frost-free days, variety selection is not optional — it is essential. Short-season varieties (tomatoes with 55–65 days to maturity, peppers with 60–70 days) are the only realistic option. Standard-season varieties planted after Memorial Day often do not mature before the first fall frost arrives in mid-September.

Spring Planting in Arizona

Spring is the primary warm-season planting window for all Arizona regions, but its timing spans nearly five months across the state — from Phoenix’s February start to Flagstaff’s June opening.

February–March: Low Desert Spring Begins

In the low desert zones 9b–11 (Phoenix, Yuma, Tucson), February is when the main warm-season vegetable garden goes in. Soil temperatures have recovered from their January minimum, days are lengthening, and the window before dangerous summer heat runs until late May.

• Direct sow tomatoes, peppers, eggplant, squash, cucumbers, and beans in Phoenix and Yuma from mid-February onwards. In Tucson, wait until early March when the risk of an unexpected freeze drops to near zero.
• Plant the final round of cool-season crops before heat forces them out: broccoli transplants started in December can finish their heading season in February–March before bolting in April’s warmth.
• Sow warm-season flowers directly — marigolds, zinnias, sunflowers, and celosias all establish quickly in low desert soils warming through February. Marigolds are especially valuable as companion plants alongside vegetables, deterring nematodes and aphids in Arizona’s alkaline soils.
• Start sweet potato slips: the low desert’s long warm season makes it ideal sweet potato territory. Start slips in February for late-March outdoor planting.

April–May: Intermediate Desert Season Opens

As the low desert transitions into pre-summer mode in April and May, the intermediate and high desert regions are hitting their prime planting window.

• Intermediate desert gardeners (Sedona, Prescott Valley, Verde Valley) can transplant warm-season crops outdoors from mid-April after the last frost has reliably passed.
• Prescott gardeners should wait until after May 1 for frost-sensitive transplants; experienced local growers often push to May 15 for peppers and basil, which are more cold-sensitive than tomatoes.
• Direct sow beans, squash, cucumbers, and corn in intermediate desert areas once soil temperature reaches 60°F. Check with an inexpensive soil thermometer — air temperature alone is misleading in Arizona’s high-altitude climates where soil can lag weeks behind air temperatures in spring.
• Plant bareroot fruit trees (apple, pear, cherry) while still dormant. University of Arizona Extension recommends bareroot stock for most Arizona fruit trees, particularly in the intermediate and high desert regions.

June: High Desert Season Opens

Flagstaff gardeners have the most compressed spring timing in the state. After the average last frost of June 1–15, the window is open — but every day matters in a 90–105 day growing season.

• Transplant all warm-season crops immediately after last frost danger has passed. Do not wait for the soil to warm further — temperatures will not get dramatically warmer before fall returns.
• Use row cover for the first two weeks after transplanting to buffer against unexpected late cold snaps, which remain possible into mid-June at Flagstaff elevations.
• Start a second round of short-season cool-season crops (radishes, lettuce, spinach) alongside warm-season crops — Flagstaff’s cool summers are the rare Arizona location where cool-season and warm-season crops can grow simultaneously.

Summer in Arizona: Heat Management and the Low Desert Pause

Arizona summers are the defining gardening challenge of the low desert. Phoenix averages 105°F in July with consistent highs above 110°F. At these temperatures, most vegetable crops stop producing and many are actively damaged: tomatoes drop blossoms above 95°F, leafy greens bolt and turn bitter, and soil surface temperatures in direct sun can reach 140°F — hot enough to damage shallow roots and kill soil microbes.

University of Arizona Cooperative Extension’s approach to low desert summers is direct: expect production to decline dramatically from June through August, and plan around this reality rather than fighting it.

What Grows Through Arizona Summers

A small group of crops genuinely handles low desert heat when supported by mulch and deep drip irrigation:

• Sweet potatoes — the ideal low desert summer crop. Plant slips in March and harvest October–November after 120–140 days. They require almost no attention through the heat once established and improve in flavor after curing.
• Okra — produces prolifically above 90°F and tolerates drought once established. Harvest every 2–3 days to keep plants productive and pods from toughening.
• Tepary beans — a traditional Sonoran Desert crop that handles extreme heat and drought better than any other bean type. University of Arizona Extension recommends them specifically for summer low desert growing.
• Black-eyed peas and cowpeas — heat-tolerant legumes that fix nitrogen and produce through the early summer before the hottest weeks arrive.
• Heat-tolerant herbs: rosemary, Mexican oregano, and epazote thrive in Arizona summers. Basil needs afternoon shade from June onwards in the low desert.

The Monsoon Effect: July–September

Arizona’s summer monsoon season (roughly July–mid-September) changes the gardening equation significantly. Tucson typically receives 6–8 inches of summer monsoon rain; Phoenix receives 3–4 inches. While not enough to eliminate irrigation, the monsoon reduces supplemental water needs and temporarily moderates humidity in a climate that is otherwise extremely dry.

Monsoon rains also create brief fungal disease risk — unusual in Arizona’s normally arid climate. Watch for powdery mildew and damping off in August after monsoon events, especially on squash, tomatoes, and newly seeded areas. The combination of standing water and 90°F nights creates short windows of disease pressure that rarely affect Arizona gardens outside this window.

Fall Planting in Arizona: The Second Season

Fall is the most productive and most distinctive season in Arizona’s low desert. As temperatures drop below 100°F in September and the long summer pause ends, the garden wakes up with unusual energy. Cool-season crops planted in September and October consistently outperform their spring counterparts in the low desert — they have longer to develop, face no race against early heat, and the flavor of vegetables like broccoli and kale genuinely improves when matured through cooling autumn weather.

For many experienced Arizona low desert gardeners, fall is when they do their most serious vegetable growing. The season runs longer, harvests are more reliable, and the pleasant temperatures of November and December make working in the garden genuinely enjoyable rather than a rush against rising heat. Check our overview of seasonal planting strategies for how to think about timing across all US growing zones and plan your transitions accordingly.

August–September: Fall Planting Begins in the Low Desert

The signal for fall planting in Phoenix and Tucson is when daytime highs consistently drop below 100°F — typically mid-August in Tucson and late August in Phoenix.

• Direct sow cool-season vegetables: kale, Swiss chard, spinach, lettuce, arugula, radishes, turnips, and mustard greens. These can go in as soil temperatures drop through late August.
• Set out broccoli, cauliflower, and cabbage transplants started from seed in July. University of Arizona Extension recommends transplanting brassicas rather than direct sowing for more reliable results in the low desert fall season.
• Sow carrots and beets directly where they will grow — root vegetables cannot be transplanted. Arizona’s fall soil temperatures cool quickly enough that September sowing produces good germination rates.
• Plant a second round of warm-season crops in early September while heat still lingers: fast-maturing bush beans (50–55 days) and summer squash can produce before first frost in Tucson (late November) and harvest well into December in Phoenix.

October–November: Peak Fall Planting and Harvest

• Plant garlic from mid-October onwards. University of Arizona Extension recommends softneck varieties (Artichoke types, Silverskin) for the low desert — these are better adapted to Arizona’s mild winters than hardneck varieties, which require extended cold vernalization the low desert rarely provides.
• Plant spring-blooming bulbs: tulips in the low desert require pre-chilling (6–8 weeks in the refrigerator) before planting in November–December because the desert winter does not provide sufficient natural cold. Daffodils, grape hyacinths, and alliums perform without pre-chilling and can go in from late October.
• Sow cool-season annuals for winter and spring color: pansies, snapdragons, alyssum, stock, and sweet peas all thrive in the low desert from October planting, blooming through April.
• Continue succession sowing fast cool-season crops every 2–3 weeks: lettuce, spinach, and arugula for continuous harvests through spring.

Winter Gardening in the Low Desert

For Phoenix and Yuma gardeners (zones 10–11), winter is an active growing season rather than a dormant period. Cool-season crops sown in September and October are typically producing their most prolific harvests in December and January, and new succession plantings of fast crops like lettuce and radishes can continue through February.

• Harvest and succession sow cool-season crops continuously through winter in zones 10–11. This is peak production for leafy greens, broccoli, cauliflower, and root vegetables.
• In Tucson (zones 9a–9b), a light frost remains possible on the coldest December and January nights. Keep frost cloth accessible for occasional protection of tender crops like lettuce, chard, and newly transplanted seedlings.
• Start onion transplants from seed in December for January–February outdoor planting. University of Arizona Extension recommends short-day onion varieties for Arizona: Granex types and Texas 1015Y perform well in low desert conditions. Long-day varieties sold in northern states will not form bulbs in Arizona.
• High desert and mountain gardeners (Flagstaff, Prescott, Show Low) are in full dormancy. Use this time to plan next year’s garden, order seeds from suppliers specializing in short-season varieties, and start cool-season transplants indoors under lights in February for a head start on the compressed season ahead.

Arizona Month-by-Month Planting Calendar

This calendar uses three reference zones: Low Desert (Phoenix/Yuma, zones 9b–11), Intermediate Desert (Tucson/Sedona, zones 8b–9a), and High Desert/Mountains (Flagstaff/Prescott, zones 5b–7b).

Top Plants for Arizona Gardens

Success in Arizona gardening is heavily dependent on variety selection. Heat-tolerant and drought-adapted varieties consistently outperform standard offerings in low desert conditions. The table below covers the most reliable performers across Arizona’s regions.

Common Arizona Gardening Challenges

Desert Heat and Intense Sun

Heat management is the central challenge of low and intermediate desert gardening. The combination of high air temperature, intense solar radiation, and low humidity creates conditions that exceed what most garden plants evolved to handle.

Three strategies are most effective. First, apply 3–4 inches of organic mulch (straw, shredded bark, or finished compost) to all vegetable beds in spring before heat arrives. Mulch keeps root-zone soil temperatures 10–15°F cooler at depth, which can make the difference between a productive tomato plant and one that stops fruiting. Second, provide afternoon shade for heat-sensitive crops from May onwards using 30–50% shade cloth on the west and south sides of beds. Third, time harvests and garden work for early morning — soil temperatures are at their daily minimum before sunrise, and heat-stressed plants visibly recover from the previous day’s damage overnight.

Alkaline Soil and Caliche Hardpan

Most Arizona soil is alkaline, with pH commonly ranging from 7.5 to 8.5. In many areas, a caliche hardpan layer sits 12–36 inches below the soil surface — a calcium carbonate layer that is impermeable to roots and drainage, forcing water to move horizontally until it can escape at the caliche layer’s edge. This creates waterlogged conditions immediately above the caliche while the surrounding surface dries out.

University of Arizona Cooperative Extension recommends two approaches. For immediate results, build raised beds 12–18 inches deep with imported soil — a mix of native soil, compost, and coarse sand creates a growing medium independent of caliche constraints. For in-ground beds, break through caliche with a digging bar before planting trees and shrubs, and amend annually with sulfur to gradually reduce alkalinity. Iron deficiency (yellowing leaves with green veins) is common in alkaline Arizona soils; use chelated iron fertilizers rather than standard iron sulfate, which becomes chemically unavailable above pH 7.5.

Water Management and Drip Irrigation

Water is Arizona’s most precious gardening resource. Low desert gardens require significantly more supplemental irrigation than gardens in humid climates: Phoenix receives only 8 inches of annual rainfall, most of which arrives in the monsoon. Vegetable gardens in Phoenix during peak summer can require 1–2 inches of supplemental water per week at 110°F.

Drip irrigation is standard in Arizona home vegetable gardens and represents a significant efficiency gain over overhead watering. Drip irrigation loses no water to evaporation, delivers moisture directly to root zones, and keeps foliage dry — reducing the fungal disease risk that spikes during monsoon season. University of Arizona Extension publishes evapotranspiration (ET) tables for Arizona cities that allow gardeners to calculate precise irrigation needs by crop type and season; these are an excellent supplement to the standard soil moisture monitoring approach for gardeners who want to dial in their watering schedules precisely.

Frequently Asked Questions About Arizona Gardening

When should I start a vegetable garden in Arizona?

In the low desert (Phoenix, Tucson, Yuma), the main spring warm-season season starts in February–March. The fall vegetable season — often more productive than spring — begins in August–September. In the intermediate desert (Sedona, Prescott Valley), spring planting starts in April after the last frost. In the high desert and mountains (Flagstaff, Prescott), the season opens after the last frost in late May or early June, with a compressed window that closes by late September.

What vegetables are easiest to grow in Arizona?

For low desert spring: tomatoes (with heat-tolerant varieties like Heatmaster or Celebrity), peppers, and green beans are reliable producers. For summer: sweet potatoes and okra genuinely thrive in Arizona heat and require minimal management once established. For fall: kale, broccoli, Swiss chard, and lettuce are some of the most productive and easiest crops to grow in the Arizona low desert fall season. For high desert gardens: broccoli, kale, Swiss chard, and short-season tomatoes (under 65 days to maturity) are the most reliable options in Flagstaff-area conditions.

Can I garden year-round in Arizona?

In the low desert zones 10–11 (Phoenix, Yuma), year-round gardening is practical. The calendar runs: cool-season crops from September through May, summer crops (okra, sweet potatoes, tepary beans) from May through September, with a brief reduction in activity during the most extreme July heat. In the intermediate desert, two distinct seasons cover approximately 7–8 months of active production. In Flagstaff and other high-elevation areas, the outdoor season is limited to approximately 90–110 days between the last and first frosts.

What should I never plant in an Arizona low desert summer?

Avoid transplanting cool-season crops (lettuce, spinach, peas, broccoli) in the low desert between May and August — they will bolt or die within days in sustained heat above 95°F. Most annual flowers commonly grown in northern gardens (impatiens, petunias, begonias) are unsuitable for low desert summers and decline rapidly above 100°F. Standard bush and pole beans struggle above 95°F; tepary beans are the heat-tolerant alternative that handles true Arizona summer conditions.

Sources

• University of Arizona Cooperative Extension — Home Gardening Resources
• University of Arizona Extension — Vegetable Garden Calendar for the Low Desert