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When to Plant Amaranth in Fergus County, MT

Fergus County, Montana Zone 4b May

Your May game plan for Fergus County, Montana

Each item below is timed to Fergus County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 20
Avg. first frost September 20
Soil temp (4") 33°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
Looking ahead to June
  • Transplants going out: amaranth
  • Direct-sowing: amaranth

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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.

Fergus County, Montana is in USDA Zone 4b. The average last spring frost is May 20 and the first fall frost is September 20, giving you a growing season of approximately 123 days.

At an elevation of 6,957 feet, Fergus County receives approximately 12 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Amaranth to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Amaranth successfully. Mulch heavily to conserve soil moisture.

Fergus County, MT (Zone 4b) Short season
123 days
Last Spring Frost May 20
123 growing days
First Fall Frost September 20
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Fergus County Soil Profile

Soil Type

Loam

Soil pH

6.4-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 12 Transplant: Jun 4 🍅 Harvest: Sep 3 – Oct 22
Recommended (50%) ✗ May not fit
Start indoors: Mar 18 Transplant: Jun 10 🍅 Harvest: Sep 9 – Oct 28
Safe Start (90%) ✗ May not fit
Start indoors: Apr 4 Transplant: Jun 27 🍅 Harvest: Sep 26 – Nov 14

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 Fergus County

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

Soil pH

Your soil pH (6.4–8.0) overlaps with Amaranth's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.3%). 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
0.4″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 775 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 4.3" 1.3" 3" 🚿 Regular watering
Jun 4.3" 0.7" 3.6" 🚿 Regular watering
Jul 4.3" 1.1" 3.2" 🚿 Regular watering
Aug 4.3" 1.3" 3" 🚿 Regular watering
Sep 4.3" 0.8" 3.5" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Fergus 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 ~1,050 GDD — county provides 1,230 GDD Good fit

Amaranth Planting Timeline — Fergus County, MT

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 – Apr 1
Transplant Outdoors June 10 Jun 10 – Jun 24
Direct Sow June 3 Jun 3 – Jun 24
Harvest September 9 Sep 9 – Oct 28

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

123 days in Fergus County

Growing Tips for Amaranth in Fergus County

Direct sow Amaranth outdoors after May 20 in Fergus County when soil has warmed and frost danger has passed.

Your 123.0-day growing season in Fergus County is tight for Amaranth (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Fergus County receives only 12" 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 Fergus County, MT?

Fergus County is in Zone 4b with an average last frost of May 20. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fergus County, MT?

Fergus County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 20 and first fall frost is September 20.

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Your Fergus County Garden Planner — Free

A 24-page printable planner built for Fergus County (Zone 4b). 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 Fergus County, MT. 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.