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When to Plant Zucchini in Hill County, MT

Hill County, Montana Zone 4a May

Your May gardening checklist

Each item below is timed to Hill County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 14
Avg. first frost September 23
Soil temp (4") 39°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Scatter zucchini into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

A few tasks this May that'll pay off in June
  • Transplants going out: zucchini
  • Starting indoors: 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.

Hill County, Montana is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 23, giving you a growing season of approximately 132 days.

At an elevation of 5,229 feet, Hill County receives approximately 14.4 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Zucchini to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Zucchini successfully. Mulch heavily to conserve soil moisture.

Hill County, MT (Zone 4a) Short season
132 days
Last Spring Frost May 14
132 growing days
First Fall Frost September 23
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Hill County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 30 Transplant: Jun 1 🍅 Harvest: Jul 20 – Sep 14
Recommended (50%) ✓ Fits season (6 days to spare)
Start indoors: Apr 2 Transplant: Jun 4 🍅 Harvest: Jul 23 – Sep 17
Safe Start (90%) ✓ Fits season (3 days to spare)
Start indoors: Apr 16 Transplant: Jun 18 🍅 Harvest: Aug 6 – Oct 1

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 Hill County

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

Soil pH

Your soil pH (6.6–8.1) overlaps with Zucchini's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Zucchini.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Zucchini.

How to Plant Zucchini

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

Succession Planting Zucchini

3
successive plantings in your 132-day season

Sow every 5.1 weeks. Last sowing by Jul 25 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.5″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 1,553 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 5.2" 1.7" 3.5" 🚿 Regular watering
Jun 5.2" 1.1" 4.1" 🚿 Regular watering
Jul 5.2" 1.2" 4" 🚿 Regular watering
Aug 5.2" 1.6" 3.6" 🚿 Regular watering
Sep 5.2" 1.2" 4" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Hill 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 ~525 GDD — county provides 1,320 GDD Excellent fit

Zucchini Planting Timeline — Hill County, MT

Zucchini Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors June 4 Jun 4 – Jun 18
Direct Sow May 28 May 28 – Jun 18
Harvest July 23 Jul 23 – Sep 17

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 4a

📆 Growing Season

132 days in Hill County

Growing Tips for Zucchini in Hill County

Direct sow Zucchini outdoors after May 14 in Hill 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.

Hill County receives only 14" 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 Hill 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 Hill County, MT?

Hill County is in Zone 4a with an average last frost of May 14. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hill County, MT?

Hill County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 23.

🌱

Your Hill County Garden Planner — Free

A 24-page printable planner built for Hill County (Zone 4a). 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 Hill County, MT. 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.