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When to Plant Amaranth in Sanborn County, SD

Sanborn County, South Dakota Zone 5a May

Top priorities for Sanborn County, South Dakota gardeners in May

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

Avg. last frost May 2
Avg. first frost October 5
Soil temp (4") 54°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Get amaranth in the ground

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Plant amaranth from seed, right in the garden

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

Get ahead of June
  • 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.

Sanborn County, South Dakota is in USDA Zone 5a. The average last spring frost is May 2 and the first fall frost is October 5, giving you a growing season of approximately 156 days.

At an elevation of 860 feet, Sanborn County receives approximately 22.3 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.

Sanborn County, SD (Zone 5a) Moderate season
156 days
Last Spring Frost May 2
156 growing days
First Fall Frost October 5
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Sanborn County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 2 Transplant: May 11 🍅 Harvest: Aug 10 – Sep 28
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Mar 7 Transplant: May 16 🍅 Harvest: Aug 15 – Oct 3
Safe Start (90%) ✗ May not fit
Start indoors: Mar 20 Transplant: May 29 🍅 Harvest: Aug 28 – Oct 16

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 Sanborn County

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

Soil pH

Your soil pH (6.7–7.2) is within Amaranth's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — 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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 666 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 0.6" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 4.3" 3.1" 1.2" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 3" 1.3" 💧 Light watering
Aug 4.3" 2.8" 1.5" 💧 Light watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 4.3" 1.5" 2.8" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Sanborn 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 1,560 GDD Excellent fit

Amaranth Planting Timeline — Sanborn County, SD

Amaranth Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors May 16 May 16 – May 30
Direct Sow May 9 May 9 – May 30
Harvest August 15 Aug 15 – Oct 3

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 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: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

156 days in Sanborn County

Growing Tips for Amaranth in Sanborn County

Direct sow Amaranth outdoors after May 02 in Sanborn County when soil has warmed and frost danger has passed.

Sanborn County receives only 22" 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 Sanborn County, SD?

Sanborn County is in Zone 5a with an average last frost of May 2. Plan your Amaranth planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sanborn County, SD?

Sanborn County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is May 2 and first fall frost is October 5.

🌱

Your Sanborn County Garden Planner — Free

A 24-page printable planner built for Sanborn County (Zone 5a). 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 Sanborn County, SD. 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.