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When to Plant Amaranth in Garfield County, CO

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.

Garfield County, Colorado is in USDA Zone 5b. The average last spring frost is May 25 and the first fall frost is September 21, giving you a growing season of approximately 119 days.

At an elevation of 7,997 feet, Garfield County receives approximately 21.3 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Amaranth to ensure they mature before fall.

Garfield County, CO (Zone 5b) Short season
119 days
Last Spring Frost May 25
119 growing days
First Fall Frost September 21

Garfield County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 19 Transplant: May 28 🍅 Harvest: Aug 27 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: Mar 30 Transplant: Jun 8 🍅 Harvest: Sep 7 – Oct 26
Safe Start (90%) ✗ May not fit
Start indoors: Apr 19 Transplant: Jun 28 🍅 Harvest: Sep 27 – Nov 15

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
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 315 gal / 100 sq ft
Drought risk

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

Amaranth needs ~1,365 GDD — county provides 1,547 GDD Good fit

Amaranth Planting Timeline โ€” Garfield County, CO

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors June 8 Jun 8 โ€“ Jun 22
Direct Sow June 1 Jun 1 โ€“ Jun 22
Harvest September 7 Sep 7 โ€“ Oct 26

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May โ€”
June Transplant Outdoors Direct Sow
July โ€”
August โ€”
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 5b

Growing Season

119 days

Growing Tips for Garfield 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 Garfield County, CO?

Garfield County is in Zone 5b with an average last frost of May 25. Plan your Amaranth planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Garfield County, CO?

Garfield County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 25 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Garfield County gardeners in Zone 5b 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 Garfield County, CO. Local conditions may vary. Last updated: April 2026.