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When to Plant Celtuce in Caribou County, ID

Celtuce (stem lettuce) is a Chinese vegetable grown for its thick, crunchy stem rather than its leaves. The peeled stem has a mild, cucumber-like flavor.

Caribou County, Idaho is in USDA Zone 4b. The average last spring frost is May 30 and the first fall frost is September 16, giving you a growing season of approximately 109 days.

At an elevation of 6,562 feet, Caribou County receives approximately 15.3 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Celtuce to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Celtuce successfully. Mulch heavily to conserve soil moisture.

Caribou County, ID (Zone 4b) Short season
109 days
Last Spring Frost May 30
109 growing days
First Fall Frost September 16

Caribou County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jul 20 – Aug 31
Recommended (50%) ✓ Fits season (4 days to spare)
Start indoors: Apr 18 Transplant: May 30 🍅 Harvest: Aug 1 – Sep 12
Safe Start (90%) ✓ Fits season (9 days to spare)
Start indoors: May 6 Transplant: Jun 17 🍅 Harvest: Aug 19 – Sep 30

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 478 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Celtuce needs ~806 GDD — county provides 1,171 GDD Excellent fit

Celtuce Planting Timeline โ€” Caribou County, ID

Celtuce Planting Calendar

Activity When Date Range
Start Indoors April 18 Apr 18 โ€“ May 2
Transplant Outdoors May 30 May 30 โ€“ Jun 13
Direct Sow May 23 May 23 โ€“ Jun 13
Fall Sowing June 24 Jun 24 โ€“ Jul 8
Harvest August 1 Aug 1 โ€“ Sep 12

Plant 0.5" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

109 days

Growing Tips for Caribou County

Direct sow in spring or start indoors. Space 12 inches apart. Harvest when stems are about 1 inch in diameter. Peel the tough outer skin to reveal the tender center.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Celtuce in Caribou County, ID?

Caribou County is in Zone 4b with an average last frost of May 30. Plan your Celtuce planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Caribou County, ID?

Caribou County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is May 30 and first fall frost is September 16.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Caribou County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

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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 Caribou County, ID. Local conditions may vary. Last updated: April 2026.