Local planting guide · Southwest
zip 85140
San Tan Valley is in USDA hardiness zone 9b, with average winter lows of 25°F to 30°F. The local growing season runs roughly 01/05 through 01/03 (~365 days). This zip falls within the Southwest growing region.
- USDA zone
- 9b 25°F to 30°F
- Last spring frost
- 01/05
- First fall frost
- 01/03
- Growing season
- 365 days
- Compatible crops
- 37
- Growing region
- Southwest
Right now in San Tan Valley
Week 18 priorities
On the docket: transplant out after last frost · direct sow after last frost. See the full calendar →
Gardening in San Tan Valley
San Tan Valley's defining feature is a frost-free growing season that spans nearly the entire year. Frost risk exists only during a narrow window in early January (Jan 3-5), making it one of the mildest climates in the continental United States. This extended season enables year-round gardening, but the dominant constraint is neither cold nor frost, but rather heat and water. Summer temperatures regularly exceed 110°F, creating stress on plants that aren't heat-adapted. Winter (January through March) provides ideal conditions for cool-season crops like lettuce, spinach, and brassicas, which thrive in the mild 50-75°F temperatures. Spring and fall serve as transition seasons where both cool- and warm-season crops flourish. Crops suited to San Tan Valley reflect this climate: perennials like fig, pomegranate, jujube, and goji berry excel in the intense heat and low humidity, while tomatoes and peppers are best grown as spring or winter crops rather than summer crops, where extreme heat triggers flower drop and reduces yields.
Regional context · Southwest
What the Southwest brings to San Tan Valley
Hot, arid, irrigated. Two growing seasons in the low desert: cool October to April, hot May to September. Date palms and citrus thrive at low elevation; apples and stone fruit at higher elevations. The chile-pepper belt of the country.
Common challenges
Issues that most often defeat home gardeners in zone 9b, drawn from the broader USDA zone profile.
- ▸ Heat stress in summer
- ▸ Insufficient chill for most apples
- ▸ Salt spray near coasts
What defeats new gardeners in San Tan Valley
Heat stress is the most significant challenge for vegetable gardeners in San Tan Valley. Tomatoes and peppers often fail to set fruit once temperatures exceed 95°F consistently, and fruit on mature plants can sunscald if not shaded. The second major issue is water access and cost. San Tan Valley's desert location means irrigation is essential year-round, and local water restrictions or rising costs can limit garden ambitions. A third challenge, particularly in early January, is the risk of occasional frost dips below the 25°F minimum for zone 9b. Though frost events in the Jan 3-5 window are infrequent, they can damage newly planted tender perennials or unexpected cold snaps can harm early-season transplants.
Crops that grow in San Tan Valley
37 crops from our catalog match zone 9b, grouped by type.
Tree fruit
11 crops
zone 9b Fig
Ficus carica
zones 7a–10b
zone 9b Asian Persimmon
Diospyros kaki
zones 7a–10a
zone 9b Pomegranate
Punica granatum
zones 7b–10a
zone 9b Jujube
Ziziphus jujuba
zones 6a–9b
zone 9b Lemon
Citrus limon
zones 9a–11b
zone 9b Orange
Citrus sinensis
zones 9a–11b
zone 9b Lime
Citrus aurantiifolia
zones 9b–11b
zone 9b Grapefruit
Citrus paradisi
zones 9a–11b
Berries
2 crops
Vegetables
18 crops
zone 9b Tomato
Solanum lycopersicum
zones 3a–10b
zone 9b Sweet Pepper
Capsicum annuum
zones 4a–10b
zone 9b Hot Pepper
Capsicum species
zones 4a–10b
zone 9b Eggplant
Solanum melongena
zones 5a–10b
zone 9b Cabbage
Brassica oleracea var. capitata
zones 3a–9b
zone 9b Kale
Brassica oleracea var. acephala
zones 3a–9b
zone 9b Collards
Brassica oleracea var. acephala
zones 4a–9b
zone 9b Cucumber
Cucumis sativus
zones 3b–10a
Herbs
6 crops
Plan the year
Planting calendar for San Tan Valley
Year-view of seed starting, transplanting, planting, pruning, fertilizing, harvest, and pest-watch windows tuned to San Tan Valley's local frost dates.
Week ? · loading
This week in San Tan Valley, AZ (zone 9b)
Quiet week in San Tan Valley, AZ (zone 9b). this week is a good time to step back and plan ahead.
Nothing critical on the calendar this week.
187 bars · 37 crops
Calendar logic combines NOAA frost normals with crop-specific timing data. Local microclimate and weather always overrules the calendar; use this as a starting point.
Top pests for zone 9b
Ranked by how many crops in your zone they affect. Click through for IPM controls and signs to watch for.
Multiple species (Aphididae)
Small soft-bodied sap-sucking insects that reproduce explosively in spring. Excrete honeydew that supports sooty mold and attracts ants. Transmit viral diseases.
Multiple species (Aleyrodidae)
Tiny white moth-like flying insects that feed on plant sap and excrete honeydew. Transmit numerous viral diseases including tomato yellow leaf curl virus.
Meloidogyne species
Microscopic soil-dwelling worm that forms galls on roots, reducing vigor and yield.
Tetranychus urticae
Tiny mite that feeds on leaf undersides, causing stippling and webbing during hot dry weather.
Multiple species (Chrysomelidae)
Tiny black or bronze jumping beetles that put hundreds of small holes in seedling leaves. Most damaging on direct-seeded brassicas and young eggplant.
Odocoileus species
Whitetail and mule deer browse can devastate orchards and gardens, particularly in winter when food is scarce. Antler rub on young trunks kills saplings outright.
Pseudococcidae spp.
Soft white waxy insects that cluster at leaf joints, fruit stems, and root crowns. Honeydew secretion supports sooty mold; root mealybugs cause decline that mimics drought.
Coccoidea spp.
Sap-sucking insects that attach to bark, leaves, and fruit, secreting honeydew that fuels sooty mold. Heavy infestations weaken trees and cause leaf yellowing.
Top diseases for zone 9b
Ranked by how many crops in your zone they affect. Click through for symptoms, controls, and resistant varieties.
Pseudoperonospora cubensis (cucurbits) and others
Water mold (oomycete, not a true fungus) that thrives in cool damp conditions. Spreads rapidly through cucurbit and brassica plantings on wind-borne spores.
Cucumber mosaic virus, Tobacco mosaic virus, and others
Family of plant viruses producing mottled yellow-and-green leaf patterns. Vectored primarily by aphids; some are seed-transmitted or spread by handling tools and tobacco products.
Pythium and Rhizoctonia species
Soil-borne complex of water molds and fungi that kill seedlings before or shortly after emergence. The single most common cause of seed-starting failures.
Fusarium oxysporum
Soil-borne fungal disease that plugs vascular tissue and kills affected plants. Persists in soil for many years; impossible to eliminate once established.
Sclerotium rolfsii
Soil-borne fungal disease most damaging in warm humid Southern conditions. White mycelial fans and small mustard-seed-sized sclerotia at the soil line are diagnostic.
Calcium deficiency physiological disorder
Not a true disease but a calcium-uptake disorder caused by inconsistent soil moisture during fruit development. The dominant cause of damaged first-fruit on home tomato plantings.
Capnodium spp.
Black fungal coating that grows on honeydew secreted by aphids, scale, mealybugs, and whiteflies. Doesn't infect plant tissue directly but blocks photosynthesis and disfigures fruit.
Tomato spotted wilt orthotospovirus (TSWV)
Virus vectored by thrips, particularly western flower thrips. Wide host range and growing global distribution. No cure once infected.
Companion planting suggestions
Beneficial pairings drawn from companion data, filtered to crops that grow in zone 9b.
- Fig + Rosemary
Rosemary tolerates the dry sites figs prefer and provides aromatic pest deterrence.
- Tomato + Basil
The classic Italian pairing. Basil's volatile oils are reported to repel hornworms and whiteflies, and the two crops share the same warm-season schedule and water needs. Plant basil between tomato cages.
- Sweet Pepper + Basil
Same warm-season culture, same watering schedule. Basil reportedly improves pepper flavor and repels aphids and thrips that are pepper's primary pests.
- Hot Pepper + Basil
Compatible heat-loving culture, similar water needs. Basil interplanted between hot pepper plants supports beneficial insects and reduces aphid pressure.
- Lettuce + Tomato
Lettuce planted at tomato's base benefits from afternoon shade as the tomato grows, extending the lettuce harvest into early summer. Different root depths avoid competition.
- Cabbage + Onion
Onion smell confuses cabbage moth. Both prefer similar moisture and fertility. The onion-cabbage interplanting is a Northern European tradition.
Soil types reference
Soil texture and pH decide what grows easily on your specific lot. Find the closest match below for crop recommendations and amendment guidance.
Practical tips for San Tan Valley
First, exploit San Tan Valley's mild winter to grow cool-season crops October through February. Lettuce, spinach, kale, broccoli, and cauliflower all thrive in the 50-75°F temperatures and produce abundant, tender harvests during months when heat-loving crops lie dormant. Second, plant tomatoes and peppers in late August to September for a spring (February-April) harvest rather than spring for a summer harvest. The early schedule avoids the brutal June-August heat that causes flower drop and reduces quality. Third, use 30-50% shade cloth over heat-sensitive crops from mid-June through August. Pomegranates and figs can handle full sun year-round, but tomatoes, peppers, and leafy greens all benefit from afternoon shade during the most intense heat. This simple practice prevents sunscald, reduces water demands, and extends harvest windows.
Frequently asked questions
- What are the best crops to grow in San Tan Valley?
Perennials like fig, pomegranate, jujube, and goji berry thrive in the intense heat and low humidity. For annuals, plant cool-season crops (lettuce, spinach, brassicas) in winter and spring/fall tomatoes and peppers. Avoid summer planting of heat-sensitive vegetables.
- When should I plant tomatoes in San Tan Valley?
Plant tomato transplants in late August to September for harvest through spring (February-April). Spring plantings for summer harvest fail due to heat-induced flower drop when temperatures exceed 95°F consistently. Winter-planted tomatoes will produce through late spring before heat stress hits.
- Do I need to worry about frost in San Tan Valley?
Frost risk is minimal, occurring only in a narrow January 3-5 window when temperatures occasionally dip below 25°F. Tender perennials planted in late December should have frost cloth nearby, but frost events are rare. The growing season is effectively 365 days.
- How do I prevent sun scald and heat damage on tomatoes and peppers?
Apply 30-50% shade cloth from mid-June through August. Afternoon shade (east or west exposure) also helps. For best results, adjust planting schedules to avoid the peak heat months entirely by harvesting before June.
- What's the best time of year to garden in San Tan Valley?
Winter and spring (January-April) are ideal, with mild temperatures and low disease pressure. Fall (October-November) is also productive. Summer requires heat-adapted crops and intensive shade and irrigation management.
- Is irrigation necessary in San Tan Valley?
Yes, year-round irrigation is essential in this desert climate. Plan your garden around local water restrictions and costs. Drought-tolerant perennials (fig, pomegranate, jujube) require less frequent watering once established, while annuals need consistent moisture.
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Frost data: NOAA Climate Normals 1991-2020, station USW00023183. Local microclimates can shift these dates by a week or more.
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