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When to Plant Amaranth in Routt County, CO

Routt County, Colorado Zone 4a April

April in the garden — Routt County, Colorado

Your garden in Routt County, Colorado is working on a schedule, even when you're not. Here's where you should be this April.

Avg. last frost June 12
Avg. first frost September 8
Soil temp (4") 27°F
Watering High
Pest pressure Low
Daylight 13.1 hrs

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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.

Routt County, Colorado is in USDA Zone 4a. The average last spring frost is June 12 and the first fall frost is September 8, giving you a growing season of approximately 88 days.

At an elevation of 5,381 feet, Routt County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Amaranth to ensure they mature before fall.

Routt County, CO (Zone 4a) Very short season
88 days
Last Spring Frost June 12
88 growing days
First Fall Frost September 8
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Routt County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 31 Transplant: Jun 23 🍅 Harvest: Sep 22 – Nov 10
Recommended (50%) ✗ May not fit
Start indoors: Apr 10 Transplant: Jul 3 🍅 Harvest: Oct 2 – Nov 20
Safe Start (90%) ✗ May not fit
Start indoors: Apr 23 Transplant: Jul 16 🍅 Harvest: Oct 15 – Dec 3

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 Routt County

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

Soil pH

Your soil pH (6.7–7.9) overlaps with Amaranth's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Amaranth

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Amaranth

Amaranth needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Amaranth Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 2.8" 0" ❄️ Dormant
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 2.2" 2.1" 💧 Light watering
Aug 4.3" 2.2" 2.1" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 Light watering
Oct 1.9" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Routt County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Amaranth 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.

Amaranth needs ~1,286 GDD — county provides 1,078 GDD May not mature

Amaranth Planting Timeline — Routt County, CO

Amaranth Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 – Apr 24
Transplant Outdoors July 3 Jul 3 – Jul 17
Direct Sow June 26 Jun 26 – Jul 17
Harvest October 2 Oct 2 – Nov 20

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

88 days in Routt County

Growing Tips for Amaranth in Routt County

Direct sow Amaranth outdoors after June 12 in Routt County when soil has warmed and frost danger has passed.

Your 88.0-day growing season in Routt County is tight for Amaranth (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Routt County receives only 24" of rain annually. Amaranth needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Amaranth in Routt County, CO?

Routt County is in Zone 4a with an average last frost of June 12. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Routt County, CO?

Routt County, Colorado is in USDA Hardiness Zone 4a. The average last spring frost is June 12 and first fall frost is September 8.

🌱

Your Routt County Garden Planner — Free

A 24-page printable planner built for Routt County (Zone 4a). 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 Routt County, CO. Local conditions may vary. Last updated: April 2026.

Sources & credits

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