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When to Plant Amaranth in Olmsted County, MN

Olmsted County, Minnesota Zone 4b May

Top priorities for Olmsted County, Minnesota gardeners in May

May is a pivotal month for Olmsted County, Minnesota gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 3
Avg. first frost October 4
Soil temp (4") 53°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Set out amaranth seedlings

    Your last frost (May 3) has passed. These warm-season crops can handle outdoor soil now.

  2. Sow amaranth where they'll grow

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

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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.

Olmsted County, Minnesota is in USDA Zone 4b. The average last spring frost is May 3 and the first fall frost is October 4, giving you a growing season of approximately 154 days.

At an elevation of 992 feet, Olmsted County receives approximately 32.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Amaranth to ensure they mature before fall.

Olmsted County, MN (Zone 4b) Moderate season
154 days
Last Spring Frost May 3
154 growing days
First Fall Frost October 4
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Olmsted County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 22 Transplant: May 17 🍅 Harvest: Aug 16 – Oct 4
Recommended (50%) ✗ May not fit
Start indoors: Mar 1 Transplant: May 24 🍅 Harvest: Aug 23 – Oct 11
Safe Start (90%) ✗ May not fit
Start indoors: Mar 16 Transplant: Jun 8 🍅 Harvest: Sep 7 – Oct 26

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 Olmsted County

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

Soil pH

Your soil pH (5.9–7.3) overlaps with Amaranth's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Amaranth.

Organic Matter

Organic matter is moderate (3.8%). 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
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 556 gal / 100 sq ft

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 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 2.4" 1.9" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Olmsted 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 ~1,129 GDD — county provides 1,655 GDD Excellent fit

Amaranth Planting Timeline — Olmsted County, MN

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 1 Mar 1 – Mar 15
Transplant Outdoors May 24 May 24 – Jun 7
Direct Sow May 17 May 17 – Jun 7
Harvest August 23 Aug 23 – Oct 11

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

154 days in Olmsted County

Growing Tips for Amaranth in Olmsted County

Direct sow Amaranth outdoors after May 03 in Olmsted County when soil has warmed and frost danger has passed.

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 Olmsted County, MN?

Olmsted County is in Zone 4b with an average last frost of May 3. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Olmsted County, MN?

Olmsted County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is May 3 and first fall frost is October 4.

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Your Olmsted County Garden Planner — Free

A 24-page printable planner built for Olmsted 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 Olmsted County, MN. 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.