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When to Plant Zucchini in Glacier County, MT

Glacier County, Montana Zone 4b May

May in the garden — Glacier County, Montana

We've pulled the most time-sensitive tasks for Glacier County, Montana this May and put them front and centre. Tackle them in order.

Avg. last frost May 22
Avg. first frost September 18
Soil temp (4") 30°F
Watering High
Pest pressure Low
Daylight 15 hrs
Coming up in June — start thinking about
  • Transplants going out: zucchini
  • Direct-sowing: 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.

Glacier County, Montana is in USDA Zone 4b. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 8,147 feet, Glacier County receives approximately 13.3 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.

Glacier County, MT (Zone 4b) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18
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Glacier County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 3 Transplant: Jun 5 🍅 Harvest: Jul 24 – Sep 18
Recommended (50%) ✗ May not fit
Start indoors: Apr 10 Transplant: Jun 12 🍅 Harvest: Jul 31 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: Apr 30 Transplant: Jul 2 🍅 Harvest: Aug 20 – Oct 15

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 Glacier County

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

Soil pH

Your soil pH (6.3–8.1) overlaps with Zucchini's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). 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 119-day season

Sow every 5.1 weeks. Last sowing by Jul 20 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.5″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 929 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 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 5.2" 1.6" 3.6" 🚿 Regular watering
Jun 5.2" 1" 4.2" 🚿 Regular watering
Jul 5.2" 1.3" 3.9" 🚿 Regular watering
Aug 5.2" 1.4" 3.8" 🚿 Regular watering
Sep 5.2" 1.1" 4.1" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Glacier 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 1,190 GDD Excellent fit

Zucchini Planting Timeline — Glacier County, MT

Zucchini Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 – Apr 24
Transplant Outdoors June 12 Jun 12 – Jun 26
Direct Sow June 5 Jun 5 – Jun 26
Harvest July 31 Jul 31 – Sep 25

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May
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 4b

📆 Growing Season

119 days in Glacier County

Growing Tips for Zucchini in Glacier County

Direct sow Zucchini outdoors after May 22 in Glacier 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.

Glacier County receives only 13" 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 Glacier 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 Glacier County, MT?

Glacier County is in Zone 4b with an average last frost of May 22. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Glacier County, MT?

Glacier County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 22 and first fall frost is September 18.

🌱

Your Glacier County Garden Planner — Free

A 24-page printable planner built for Glacier County (Zone 4b). 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 Glacier 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.