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When to Plant Amaranth in Canyon County, ID

Amaranth is an ancient grain crop with edible leaves and seeds, rich in protein and micronutrients. It thrives in warm conditions and is drought-tolerant once established.

Canyon County, Idaho is in USDA Zone 6b. The average last spring frost is May 4 and the first fall frost is October 10, giving you a growing season of approximately 159 days.

At an elevation of 4,953 feet, Canyon County receives approximately 13.3 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Amaranth during the growing season. With low rainfall, drip irrigation is essential for growing Amaranth successfully. Mulch heavily to conserve soil moisture.

Canyon County, ID (Zone 6b) Moderate season
159 days
Last Spring Frost May 4
159 growing days
First Fall Frost October 10

Canyon County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Feb 23 Transplant: May 4 🍅 Harvest: Aug 3 – Sep 21
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Mar 9 Transplant: May 18 🍅 Harvest: Aug 17 – Oct 5
Safe Start (90%) ✗ May not fit
Start indoors: Apr 11 Transplant: Jun 20 🍅 Harvest: Sep 19 – Nov 7

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
0.4″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,102 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Amaranth needs ~1,601 GDD — county provides 2,424 GDD Excellent fit

Amaranth Planting Timeline โ€” Canyon County, ID

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 โ€“ Mar 23
Transplant Outdoors May 18 May 18 โ€“ Jun 1
Direct Sow May 11 May 11 โ€“ Jun 1
Harvest August 17 Aug 17 โ€“ Oct 5

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6b

Growing Season

159 days

Growing Tips for Canyon County

Direct sow after last frost when soil is warm. Thin seedlings to 18 inches apart. Harvest leaves when young and tender; harvest seeds when flower heads begin to dry.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Level Up Your Garden

Frequently Asked Questions

When should I plant Amaranth in Canyon County, ID?

Canyon County is in Zone 6b with an average last frost of May 4. Plan your Amaranth planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Canyon County, ID?

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

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Canyon County gardeners in Zone 6b 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 Canyon County, ID. Local conditions may vary. Last updated: April 2026.