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When to Plant Zucchini in Maricopa County, AZ

Maricopa County, Arizona Zone 9b April

This month in Maricopa County, Arizona

If you only do a handful of things in the garden this April, make it these. They're sequenced around your zone's frost timing.

Avg. last frost January 31
Avg. first frost December 6
Soil temp (4") 59°F
Watering Critical
Pest pressure High
Daylight 12.8 hrs
  1. Collect zucchini at their peak

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

May will be here before you know it — start on
  • First harvests: zucchini

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Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Maricopa County, Arizona is in USDA Zone 9b. The average last spring frost is January 31 and the first fall frost is December 6, giving you a growing season of approximately 309 days.

At an elevation of 4,014 feet, Maricopa County receives approximately 12.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 108°F, so Zucchini may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Zucchini will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Zucchini successfully. Mulch heavily to conserve soil moisture.

Maricopa County, AZ (Zone 9b) Year-round
309 days
Last Spring Frost January 31
309 growing days
First Fall Frost December 6

Maricopa County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.2-8.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (206 days to spare)
Start indoors: Dec 20 Transplant: Jan 24 🍅 Harvest: Mar 14 – May 9
Recommended (50%) ✓ Fits season (197 days to spare)
Start indoors: Jan 3 Transplant: Feb 7 🍅 Harvest: Mar 28 – May 23
Safe Start (90%) ✓ Fits season (192 days to spare)
Start indoors: Jan 30 Transplant: Mar 6 🍅 Harvest: Apr 24 – Jun 19

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Maricopa County

How your county's soil matches Zucchini's growing requirements.

Soil pH

Your soil pH (7.2–8.5) is more alkaline than Zucchini prefers (6.0–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Maricopa County warms quickly in spring but drains fast. Zucchini will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is low (0.7%). Add 2-3 inches of compost before planting Zucchini.

How to Plant Zucchini

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Zucchini

8
successive plantings in your 309-day season

Sow every 5.1 weeks. Last sowing by Oct 07 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.2″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 3,412 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan 5.2" 0.9" 4.3" 🚿 Regular watering
Feb 5.2" 0.8" 4.4" 🚿 Regular watering
Mar 5.2" 0.7" 4.5" 🚿 Regular watering
Apr 5.2" 0.5" 4.7" 🚿 Regular watering
May 5.2" 0.3" 4.9" 🚿 Regular watering
Jun 5.2" 0.4" 4.8" 🚿 Regular watering
Jul 5.2" 2.1" 3.1" 🚿 Regular watering
Aug 5.2" 2.3" 2.9" 🚿 Regular watering
Sep 5.2" 1.9" 3.3" 🚿 Regular watering
Oct 5.2" 1.2" 4" 🚿 Regular watering
Nov 5.2" 0.6" 4.6" 🚿 Regular watering
Dec 5.2" 0.8" 4.4" 🚿 Regular watering

Water needs are for active growing months only (Jan–Dec in Maricopa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Zucchini Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Zucchini needs ~1,628 GDD — county provides 9,610 GDD Excellent fit

Zucchini Planting Timeline — Maricopa County, AZ

Zucchini Planting Calendar

Activity When Date Range
Start Indoors January 3 Jan 3 – Jan 17
Transplant Outdoors February 7 Feb 7 – Feb 21
Direct Sow January 31 Jan 31 – Feb 21
Harvest March 28 Mar 28 – May 23

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors Direct Sow
February Transplant Outdoors Direct Sow
March Harvest
April Harvest
May Harvest
June
July
August
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 2-3 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

309 days in Maricopa County

Growing Tips for Zucchini in Maricopa County

Direct sow Zucchini outdoors after January 31 in Maricopa County when soil has warmed and frost danger has passed.

Sandy soil in Maricopa County dries quickly — mulch Zucchini with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 108°F in Maricopa County, provide afternoon shade for Zucchini and water deeply in the morning.

Your generous 310.0-day season in Maricopa County allows multiple plantings of Zucchini. Sow every 22.0 days for continuous harvest.

Common pests for Zucchini in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Maricopa County, AZ?

Maricopa County is in Zone 9b with an average last frost of January 31. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Maricopa County, AZ?

Maricopa County, Arizona is in USDA Hardiness Zone 9b. The average last spring frost is January 31 and first fall frost is December 6.

🌱

Your Maricopa County Garden Planner — Free

A 24-page printable planner built for Maricopa County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Maricopa County, AZ. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.