Blog

When to Plant Zucchini in Madison County, ID

Madison County, Idaho Zone 5a May

Your May gardening checklist

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Madison County, Idaho.

Avg. last frost May 31
Avg. first frost September 11
Soil temp (4") 41°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
Get ahead of June
  • Transplants going out: zucchini
  • Direct-sowing: zucchini

Instant PDF download. No spam, unsubscribe any time.

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.

Madison County, Idaho is in USDA Zone 5a. The average last spring frost is May 31 and the first fall frost is September 11, giving you a growing season of approximately 103 days.

At an elevation of 6,385 feet, Madison County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Zucchini during the growing season. With low rainfall, drip irrigation is essential for growing Zucchini successfully. Mulch heavily to conserve soil moisture.

Madison County, ID (Zone 5a) Short season
103 days
Last Spring Frost May 31
103 growing days
First Fall Frost September 11

Madison County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 16 Transplant: Jun 4 🍅 Harvest: Jul 23 – Sep 17
Recommended (50%) ✗ May not fit
Start indoors: Apr 26 Transplant: Jun 14 🍅 Harvest: Aug 2 – Sep 27
Safe Start (90%) ✗ May not fit
Start indoors: May 17 Transplant: Jul 5 🍅 Harvest: Aug 23 – Oct 18

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 Madison County

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

Soil pH

Your soil pH (6.2–7.8) overlaps with Zucchini's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Madison County is excellent for Zucchini — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Zucchini.

How to Plant Zucchini

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

Succession Planting Zucchini

2
successive plantings in your 103-day season

Sow every 5.1 weeks. Last sowing by Jul 13 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 468 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 5.2" 2.5" 2.7" 🚿 Regular watering
Jun 5.2" 1.2" 4" 🚿 Regular watering
Jul 5.2" 1.6" 3.6" 🚿 Regular watering
Aug 5.2" 2.2" 3" 🚿 Regular watering
Sep 5.2" 1.6" 3.6" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Madison 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 ~722 GDD — county provides 1,416 GDD Excellent fit

Zucchini Planting Timeline — Madison County, ID

Zucchini Planting Calendar

Activity When Date Range
Start Indoors April 26 Apr 26 – May 10
Transplant Outdoors June 14 Jun 14 – Jun 28
Direct Sow June 7 Jun 7 – Jun 28
Harvest August 2 Aug 2 – Sep 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · 1-2 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

103 days in Madison County

Growing Tips for Zucchini in Madison County

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

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.

Madison County receives only 19" of rain annually. Zucchini needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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.

Recommended Zucchini Varieties for Madison County

Quick-producing varieties for shorter seasons

Black Beauty (50d) Raven (48d) Eight Ball (40d)

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 Madison County, ID?

Madison County is in Zone 5a with an average last frost of May 31. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Madison County, ID?

Madison County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 31 and first fall frost is September 11.

🌱

Your Madison County Garden Planner — Free

A 24-page printable planner built for Madison County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

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

Sources & credits

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