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When to Plant Amaranth in Butte 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.

Butte County, Idaho is in USDA Zone 4b. The average last spring frost is June 1 and the first fall frost is September 14, giving you a growing season of approximately 105 days.

At an elevation of 7,254 feet, Butte County receives approximately 24 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.

Butte County, ID (Zone 4b) Short season
105 days
Last Spring Frost June 1
105 growing days
First Fall Frost September 14

Butte County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 19 Transplant: Jun 11 🍅 Harvest: Sep 10 – Oct 29
Recommended (50%) ✗ May not fit
Start indoors: Mar 30 Transplant: Jun 22 🍅 Harvest: Sep 21 – Nov 9
Safe Start (90%) ✗ May not fit
Start indoors: Apr 15 Transplant: Jul 8 🍅 Harvest: Oct 7 – Nov 25

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 Butte County

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

Soil pH

Your soil pH (6.8โ€“8.4) is more alkaline than Amaranth prefers (6.0โ€“7.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Butte County is excellent for Amaranth โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). 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
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 45 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” 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 โ€” 1.8" 0" โ„๏ธ Dormant
Feb โ€” 1.4" 0" โ„๏ธ Dormant
Mar โ€” 2.1" 0" โ„๏ธ Dormant
Apr โ€” 2.4" 0" โ„๏ธ Dormant
May โ€” 3" 0" โ„๏ธ Dormant
Jun 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Jul 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Aug 4.3" 2.7" 1.6" ๐Ÿ’ง Light watering
Sep 4.3" 1.7" 2.6" ๐Ÿšฟ Regular watering
Oct โ€” 2.2" 0" โ„๏ธ Dormant
Nov โ€” 1.6" 0" โ„๏ธ Dormant
Dec โ€” 1.4" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Junโ€“Sep in Butte County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 ~1,365 GDD — county provides 1,365 GDD Tight fit

Amaranth Planting Timeline โ€” Butte County, ID

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors June 22 Jun 22 โ€“ Jul 6
Direct Sow June 15 Jun 15 โ€“ Jul 6
Harvest September 21 Sep 21 โ€“ Nov 9

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 Transplant Outdoors Direct Sow
August โ€”
September Harvest
October Harvest
November Harvest
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท Only during dry spells

๐Ÿ“… Days to Maturity

90โ€“120 days

๐Ÿงช Soil pH

Needs 6โ€“7.5 ยท Your soil: too_alkaline

๐Ÿ—บ๏ธ USDA Zone

Zone 4b

๐Ÿ“† Growing Season

105 days in Butte County

Growing Tips for Amaranth in Butte County

Direct sow Amaranth outdoors after June 01 in Butte County when soil has warmed and frost danger has passed.

Your 105.0-day growing season in Butte County is tight for Amaranth (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Butte County receives only 24" of rain annually. Amaranth needs consistent moisture โ€” 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 Butte County, ID?

Butte County is in Zone 4b with an average last frost of June 1. Plan your Amaranth planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Butte County, ID?

Butte County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 1 and first fall frost is September 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Butte 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 Butte County, ID. Local conditions may vary. Last updated: April 2026.