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When to Plant Amaranth in Washtenaw County, MI

Washtenaw County, Michigan Zone 6a May

May to-do list for Washtenaw County, Michigan

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Washtenaw County, Michigan.

Avg. last frost April 29
Avg. first frost October 16
Soil temp (4") 61°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Get amaranth in the ground

    Frost risk is low now in Washtenaw County, Michigan. If you've been covering beds overnight, you can stop.

  2. Direct-sow amaranth

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Coming up in June — start thinking about
  • Starting indoors: 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.

Washtenaw County, Michigan is in USDA Zone 6a. The average last spring frost is April 29 and the first fall frost is October 16, giving you a growing season of approximately 170 days.

At an elevation of 737 feet, Washtenaw County receives approximately 38 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Amaranth during the growing season.

Washtenaw County, MI (Zone 6a) Moderate season
170 days
Last Spring Frost April 29
170 growing days
First Fall Frost October 16
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Washtenaw County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (13 days to spare)
Start indoors: Mar 1 Transplant: May 10 🍅 Harvest: Aug 9 – Sep 27
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Mar 4 Transplant: May 13 🍅 Harvest: Aug 12 – Sep 30
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Mar 18 Transplant: May 27 🍅 Harvest: Aug 26 – Oct 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 Washtenaw County

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

Soil pH

Your soil pH (6.2–7.2) is within Amaranth's preferred range (6.0–7.5).

Soil Texture

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

Drainage

Drainage is adequate for Amaranth.

Organic Matter

Organic matter is excellent (4.5%) — Amaranth will thrive.

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 546 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 1.8" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 4" 0.3" 💧 Light watering
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 4.5" 0" ✅ Rainfall sufficient
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Washtenaw 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 ~1,680 GDD — county provides 2,720 GDD Excellent fit

Amaranth Planting Timeline — Washtenaw County, MI

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 6 May 6 – May 27
Harvest August 12 Aug 12 – Sep 30

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
July
August Harvest
September Harvest
October
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: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

170 days in Washtenaw County

Growing Tips for Amaranth in Washtenaw County

Direct sow Amaranth outdoors after April 29 in Washtenaw 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 Washtenaw County, MI?

Washtenaw County is in Zone 6a with an average last frost of April 29. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washtenaw County, MI?

Washtenaw County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 29 and first fall frost is October 16.

🌱

Your Washtenaw County Garden Planner — Free

A 24-page printable planner built for Washtenaw County (Zone 6a). 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 Washtenaw County, MI. 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.