Understanding Phoenix's Two Growing Seasons

The single biggest mental shift for anyone new to Phoenix gardening is understanding that we don't grow when most of the country grows. National gardening resources, seed catalogs, and magazine articles are almost entirely written for gardeners in the northern and eastern United States — places where summer is the main growing season. In Phoenix, summer is when most gardens rest.

We have two growing seasons: a cool season (fall/winter) and a warm season (spring). Understanding both — and the extreme summer in between — changes everything about how you garden here.

The Cool Season: September – February

This is Phoenix's most productive and most pleasant growing season. Temperatures from October through February are ideal for a wide range of vegetables. Our "winter" is what gardeners in other regions call perfect growing weather.

What grows: Leafy greens (lettuce, kale, spinach, arugula, chard), broccoli, cauliflower, cabbage, carrots, beets, radishes, snap peas, onions, garlic, and cool-season herbs (cilantro, parsley, dill).

The advantage: Cool, dry weather means fewer pests and diseases. Crops grow clean. The mild temperatures are also genuinely wonderful — October through January is the best time to actually be in your garden.

The challenge: Occasional frost (rare but possible, especially in the East Valley foothills and Scottsdale). Most vegetables tolerate light frost, but a hard freeze can damage tender plants. Keep frost cloth on hand.

The Warm Season: January – May

The spring warm season is when most heat-loving vegetables — tomatoes, peppers, cucumbers, squash, eggplant, melons — are grown. It's a compressed season because it begins in January (cold nights) and ends when June heat arrives (usually by Memorial Day).

What grows: Tomatoes (plant Jan-Feb, harvest Apr-May — see when to plant tomatoes in Phoenix), peppers (plant Feb-Mar, harvest Apr-June), cucumbers and squash (plant Feb-Mar, harvest Apr-May), eggplant (plant Feb-Mar, harvest May and beyond), melons (plant Feb-Mar, harvest May-June), basil and warm-season herbs.

The challenge: You're racing against the summer heat. Tomatoes stop setting fruit above 95°F. Most spring crops need to be done before June. Time is your most limited resource in the spring garden.

⚠️ Plant early for spring crops Every week you delay planting spring crops is a week lost from the end of the season, not the beginning. The heat comes on the same schedule regardless. Plant tomatoes and peppers as close to January 15–February 1 as possible.

Summer: June – September (The Pause)

Phoenix summers are genuinely extreme — 100–115°F days, overnight lows in the 85–90°F range, and almost zero humidity until the July-August monsoon season. Most vegetables cannot survive this, and most gardens go into summer rest mode.

What can survive summer:

Okra — Loves heat, produces all summer. One of Phoenix's best summer crops.
Sweet potatoes — Vines through the heat, harvest in fall.
Armenian cucumber — Heat-tolerant, unlike standard cucumbers. Produces into July with enough water.
Malabar spinach — A tropical climbing vine, not true spinach, but the leaves are similar. Loves heat.
Long beans / yard-long beans — Tolerate heat much better than bush beans.
Eggplant — With shade cloth, many varieties survive and rebound in fall.
Peppers — Similar to eggplant — with shade cloth protection, they can persist through summer.

For most gardeners, June-September is best used to rest beds, amend soil with compost, and plan the fall garden. Don't fight the heat — work around it.

The Monsoon: July – September

Phoenix's monsoon season (July through mid-September) brings dramatic storms, high humidity, and significant rainfall. This changes gardening dynamics:

Watering frequency can decrease significantly during active monsoon
Humidity brings fungal diseases that are rare in our dry season — watch for powdery mildew
Soil stays moist longer between rains
The humidity actually helps stressed plants survive better than the dry June heat

The monsoon also signals the beginning of the end of the extreme summer. As monsoon rains slow in September, temperatures start to moderate — and it's time to start the fall garden.

Building Your Phoenix Garden Calendar

The simplest way to think about Phoenix gardening: work backwards from the seasonal extremes. Plant spring crops early enough to finish before June heat. Plant fall crops early enough to establish before December cold slows growth. Everything else fills in around those two anchors.

For specific planting dates, see the Phoenix Planting Calendar, or pick up the downloadable PDF version for a complete month-by-month reference.