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When to plant Cucumber in Custer County, ID

Custer County's 79-day season only supports one Cucumber planting per year. Sow between June 25 and July 16 for the best chance at full maturity before September 5.

When to Plant Cucumber in Custer County, ID

Custer County, Idaho Zone 5b June

June to-do list for Custer County, Idaho

Your garden in Custer County, Idaho is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost June 18
Avg. first frost September 5
Soil temp (4") 51°F
Watering High
Pest pressure High
Daylight 15.3 hrs
  1. Put cucumber seeds straight in the ground

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

July prep starts now
  • Transplants going out: cucumber
  • Starting indoors: 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.

Custer County, Idaho is in USDA Zone 5b. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.

At an elevation of 5,189 feet, Custer County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Cucumber to ensure they mature before fall.

Custer County, ID (Zone 5b) Very short season
79 days
Last Spring Frost June 18
79 growing days
First Fall Frost September 5

Custer County Soil Profile

Soil Type

Loam

Soil pH

6.3-8

Drainage

Well Drained

Cucumber Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: May 7 Transplant: Jun 25 🍅 Harvest: Aug 20 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: May 14 Transplant: Jul 2 🍅 Harvest: Aug 27 – Oct 22
Safe Start (90%) ✗ May not fit
Start indoors: May 25 Transplant: Jul 13 🍅 Harvest: Sep 7 – Nov 2

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 Custer County

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

Soil pH

Your soil pH (6.3–8.0) is more alkaline than Cucumber prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Cucumber

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

Cucumber Water Budget

Plant needs
1.5″/week
Rainfall provides
1.1″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 342 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 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 2.3" 0" ❄️ Dormant
Jun 6.5" 1.5" 5" 🚿 Regular watering
Jul 6.5" 2" 4.5" 🚿 Regular watering
Aug 6.5" 2.1" 4.4" 🚿 Regular watering
Sep 6.5" 1.7" 4.8" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Custer 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 ~600 GDD — county provides 790 GDD Excellent fit

Cucumber Planting Timeline — Custer County, ID

Cucumber Planting Calendar

Activity When Date Range
Start Indoors May 14 May 14 – May 28
Transplant Outdoors July 2 Jul 2 – Jul 16
Direct Sow June 25 Jun 25 – Jul 16
Harvest August 27 Aug 27 – Oct 22

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Start Indoors
June 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 · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

79 days in Custer County

Growing Tips for Cucumber in Custer County

Direct sow Cucumber outdoors after June 18 in Custer 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.

Custer County receives only 21" 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 Custer County, ID?

Custer County is in Zone 5b with an average last frost of June 18. Plan your Cucumber planting based on this frost date — see the calendar above for exact timing.

What planting zone is Custer County, ID?

Custer County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is June 18 and first fall frost is September 5.

When should I plant Cucumber in Custer County, ID?

In Custer County, ID, plant Cucumber after the last frost (around June 18) and before the first frost (around September 5). Best results when soil holds above 50°F.

What growing zone is Custer County, ID for Cucumber?

Custer County sits in USDA Zone 5b. Cucumber grows reliably in zones 3a through 11b, so it's a good fit here.

Can Cucumber grow in Custer County's climate?

Yes — Cucumber grows well in Custer County's temperate climate. Custer County averages a 79-day frost-free season, with last frost around June 18 and first frost around September 5.

🌱

Your Custer County Garden Planner — Free

A 22-page printable planner built for Custer County (Zone 5b). 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 Custer County, ID. Local conditions may vary. Last updated: June 2026.

Sources & credits

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