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When to Plant Cucumber in Gallatin County, MT

Gallatin County, Montana Zone 5a May

Gallatin County, Montana gardeners: here's your May plan

A quick May briefing for Gallatin County, Montana gardeners — what's urgent, what's next, and what can wait.

Avg. last frost June 8
Avg. first frost September 19
Soil temp (4") 27°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
Get ahead of June
  • Transplants going out: cucumber
  • Direct-sowing: cucumber

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Cucumbers are a warm-season vine crop available in slicing and pickling varieties. They are prolific producers when given warmth, moisture, and a trellis to climb.

Gallatin County, Montana is in USDA Zone 5a. The average last spring frost is June 8 and the first fall frost is September 19, giving you a growing season of approximately 103 days.

At an elevation of 8,376 feet, Gallatin County receives approximately 12.4 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Cucumber to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Cucumber successfully. Mulch heavily to conserve soil moisture.

Gallatin County, MT (Zone 5a) Short season
103 days
Last Spring Frost June 8
103 growing days
First Fall Frost September 19

Gallatin County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 20 Transplant: Jun 8 🍅 Harvest: Aug 3 – Sep 28
Recommended (50%) ✗ May not fit
Start indoors: May 4 Transplant: Jun 22 🍅 Harvest: Aug 17 – Oct 12
Safe Start (90%) ✗ May not fit
Start indoors: May 16 Transplant: Jul 4 🍅 Harvest: Aug 29 – Oct 24

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 Gallatin County

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

Soil pH

Your soil pH (6.2–8.1) is more alkaline than Cucumber prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Cucumber.

How to Plant Cucumber

0.5"
Planting Depth
24"
Between Plants
48"
Between Rows

Succession Planting Cucumber

2
successive plantings in your 103-day season

Sow every 5.7 weeks. Last sowing by Jul 11 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.5″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 1,094 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Cucumber

Cucumber needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Cucumber Needs Rainfall You Supplement Action
Jan 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 1.3" 0" ❄️ Dormant
Jun 6.5" 0.8" 5.7" 🚿 Regular watering
Jul 6.5" 1" 5.5" 🚿 Regular watering
Aug 6.5" 1.5" 5" 🚿 Regular watering
Sep 6.5" 1" 5.5" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

Cucumber 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.

Cucumber needs ~690 GDD — county provides 1,184 GDD Excellent fit

Cucumber Planting Timeline — Gallatin County, MT

Cucumber Planting Calendar

Activity When Date Range
Start Indoors May 4 May 4 – May 18
Transplant Outdoors June 22 Jun 22 – Jul 6
Direct Sow June 15 Jun 15 – Jul 6
Harvest August 17 Aug 17 – Oct 12

Plant 0.5" deep · 24" apart · Rows 48" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

103 days in Gallatin County

Growing Tips for Cucumber in Gallatin County

Direct sow Cucumber outdoors after June 08 in Gallatin County when soil has warmed and frost danger has passed.

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

Gallatin County receives only 12" of rain annually. Cucumber needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after last frost or start indoors 3 weeks early. Provide a trellis for vining types to save space and improve air circulation. Harvest frequently to encourage production.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Sage

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cucumber in Gallatin County, MT?

Gallatin County is in Zone 5a with an average last frost of June 8. Plan your Cucumber planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gallatin County, MT?

Gallatin County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 8 and first fall frost is September 19.

🌱

Your Gallatin County Garden Planner — Free

A 24-page printable planner built for Gallatin 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.

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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 Gallatin 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.