Why Arizona Gets a Second Growing Season in Fall
Much of Arizona benefits from two growing seasons each year — spring and fall — rather than just one. As summer heat eases, cooler conditions open up a second window for growing many of the same cool-season vegetables that gardeners elsewhere plant in early spring. Because Arizona’s cool season isn’t especially long, it generally helps to choose varieties with a shorter number of days to harvest so crops can mature before conditions turn too cold or too hot again.
When to Start Your Fall Garden in Arizona
Exact timing varies with elevation and local climate — low desert valleys and higher elevations like Flagstaff don’t follow the same calendar — but a general three-phase timeline is a useful starting point for low desert areas like Phoenix and Tucson. Much of Arizona’s low desert falls in USDA zone 9, so our guide to Zone 9 plants is a useful companion for perennials and shrubs beyond the fall vegetable garden.
July and August: Prep and Early Starts
This is generally the time to prepare your soil and get a jump on crops that need a longer runway. Tilling soil roughly 8-12 inches deep, clearing debris and weeds, and mixing in 2-3 inches of compost or other organic matter are reasonable prep steps during late July or early August. It’s also around this time that many gardeners start seeds indoors for crops like tomatoes, peppers, and broccoli, so they’re ready to transplant once temperatures ease.
September: Direct-Sowing and Transplanting
As the weather starts to cool down, September tends to be when earlier indoor starts (tomatoes, peppers, broccoli) get transplanted outdoors, generally timed for when daytime highs are no longer consistently extreme. Other crops, including carrots, spinach, and chives, can typically be direct-sown from seed outdoors around this time as well.
October and November: Peak Planting Window
October and November are generally considered the peak window for cool-season vegetable production in Arizona’s low desert, along with crops like garlic and winter peas. If you’re comparing timing with a different climate, our fall garden guide for Pennsylvania shows how much later a typical frost-driven fall season runs elsewhere in the country.
What to Plant in an Arizona Fall Garden
Vegetables
Good cool-season candidates for an Arizona fall garden include beans, beets, bok choy, broccoli, carrots, cauliflower, celery, chives, kale, leaf lettuce, peas, peppers, spinach, and tomatoes. Leafy greens like kale, spinach, and Swiss chard tend to do well in milder autumn temperatures, and kale in particular is reported to keep growing even when temperatures dip slightly below freezing. Root vegetables such as carrots, beets, and radishes are also good options for this season — cooler soil is commonly said to help them develop a sweeter flavor. Peas planted in fall typically produce a harvest in late winter or early spring.
Fall Flowers
If you want color alongside your vegetables, geraniums, snapdragons, petunias, and lobelia are popular choices for Arizona’s cooler fall months, generally thriving in temperatures that would stress them during peak summer heat.
Preparing Soil and Site for Fall Planting
Choose a spot that gets roughly six to eight hours of sunlight, ideally with some afternoon shade if your yard allows for it. Raised beds can offer more control over soil quality, while containers are a flexible option if you’re short on space or want to move plants as conditions change. Before planting, watering the soil a few times helps distribute any amendments evenly and creates a more welcoming environment for new plants, especially if the bed sat unused over summer.
Desert-Specific Tips for Fall Success
A few habits seem to matter more in desert fall gardens than elsewhere. Providing temporary shade cloth until outdoor temperatures drop consistently below roughly 90°F can help protect young plants during the transition out of summer heat. Many experienced desert gardeners also plant in the evening, giving seedlings a chance to settle in before facing a full day of sun. Choosing heat-tolerant, slow-to-bolt varieties is also widely recommended for a smoother transition into the cool season. If you’re new to a cooler-climate fall garden in general, our fall garden guide for Michigan is a useful point of contrast for how differently timing and frost protection work in a non-desert climate.
FAQ
What should I plant in the fall in Arizona? Cool-season vegetables like broccoli, carrots, spinach, kale, and peas, along with fall-friendly flowers like snapdragons and petunias, are reasonable choices for an Arizona fall garden.
When to start fall garden in Arizona? Soil prep and early indoor seed-starting generally begin in July and August, with direct-sowing and transplanting in September, and peak planting continuing through October and November.
What vegetables can I plant in October in Arizona? October generally falls within Arizona’s peak cool-season planting window, which includes crops like carrots, broccoli, cauliflower, leafy greens, garlic, and winter peas.
What month to start a fall garden? In Arizona’s low desert, fall garden prep typically starts in July or August, though exact timing depends on elevation and local climate.