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When to Plant Cucumber in Twin Falls County, ID

Twin Falls County, Idaho Zone 6b May

What to do in May

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

Avg. last frost May 10
Avg. first frost October 4
Soil temp (4") 49°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
  1. Harden off and plant cucumber

    Your last frost (May 10) has passed. These warm-season crops can handle outdoor soil now.

  2. Seed cucumber outdoors

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Coming up in June — start thinking about
  • 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.

Twin Falls County, Idaho is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.

At an elevation of 4,584 feet, Twin Falls County receives approximately 21.8 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Cucumber during the growing season.

Twin Falls County, ID (Zone 6b) Short season
147 days
Last Spring Frost May 10
147 growing days
First Fall Frost October 4
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Twin Falls County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Mar 27 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 4
Recommended (50%) ✓ Fits season (21 days to spare)
Start indoors: Apr 5 Transplant: May 24 🍅 Harvest: Jul 19 – Sep 13
Safe Start (90%) ✓ Fits season (14 days to spare)
Start indoors: Apr 30 Transplant: Jun 18 🍅 Harvest: Aug 13 – Oct 8

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 Twin Falls County

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

Soil pH

Your soil pH (6.5–8.0) is more alkaline than Cucumber prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Cucumber.

How to Plant Cucumber

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

Succession Planting Cucumber

3
successive plantings in your 147-day season

Sow every 5.7 weeks. Last sowing by Jul 26 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,377 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.6" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 6.5" 2.3" 4.2" 🚿 Regular watering
Jun 6.5" 1.6" 4.9" 🚿 Regular watering
Jul 6.5" 1.9" 4.6" 🚿 Regular watering
Aug 6.5" 2.4" 4.1" 🚿 Regular watering
Sep 6.5" 1.9" 4.6" 🚿 Regular watering
Oct 6.5" 2.1" 4.4" 🚿 Regular watering
Nov 1.3" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Twin Falls 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 ~870 GDD — county provides 2,131 GDD Excellent fit

Cucumber Planting Timeline — Twin Falls County, ID

Cucumber Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest July 19 Jul 19 – Sep 13

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors 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

1.5"/week · 2-3 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

147 days in Twin Falls County

Growing Tips for Cucumber in Twin Falls County

Direct sow Cucumber outdoors after May 10 in Twin Falls 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.

Twin Falls County receives only 22" 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 Twin Falls County, ID?

Twin Falls County is in Zone 6b with an average last frost of May 10. Plan your Cucumber planting based on this frost date — see the calendar above for exact timing.

What planting zone is Twin Falls County, ID?

Twin Falls County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 4.

🌱

Your Twin Falls County Garden Planner — Free

A 24-page printable planner built for Twin Falls County (Zone 6b). 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 Twin Falls 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.