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When to Plant Scallions in Bon Homme County, SD

Bon Homme County, South Dakota Zone 5a May

Your May game plan for Bon Homme County, South Dakota

We've pulled the most time-sensitive tasks for Bon Homme County, South Dakota this May and put them front and centre. Tackle them in order.

Avg. last frost May 1
Avg. first frost October 6
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Move scallions into the garden

    Frost risk is low now in Bon Homme County, South Dakota. If you've been covering beds overnight, you can stop.

Before June arrives, get these ready
  • Starting indoors: scallions
  • First harvests: scallions

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Scallions (green onions) are mild-flavored alliums harvested for their slender green tops and white bases. They are quick-growing and perfect for succession planting.

Bon Homme County, South Dakota is in USDA Zone 5a. The average last spring frost is May 1 and the first fall frost is October 6, giving you a growing season of approximately 158 days.

At an elevation of 771 feet, Bon Homme County receives approximately 28.1 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Scallions to ensure they mature before fall.

Bon Homme County, SD (Zone 5a) Moderate season
158 days
Last Spring Frost May 1
158 growing days
First Fall Frost October 6

Bon Homme County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (77 days to spare)
Start indoors: Mar 20 Transplant: Apr 24 🍅 Harvest: Jun 19 – Jul 17
Recommended (50%) ✓ Fits season (74 days to spare)
Start indoors: Mar 27 Transplant: May 1 🍅 Harvest: Jun 26 – Jul 24
Safe Start (90%) ✓ Fits season (71 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jul 9 – Aug 6

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 Bon Homme County

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

Soil pH

Your soil pH (6.4–7.4) overlaps with Scallions's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Bon Homme County is excellent for Scallions — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.2%) — Scallions will thrive.

How to Plant Scallions

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Scallions

3
successive plantings in your 158-day season

Sow every 5.7 weeks. Last sowing by Jul 28 to harvest before frost.

For a dedicated fall crop, sow by Jul 28.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 427 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Scallions

Scallions needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Scallions Needs Rainfall You Supplement Action
Jan 0.7" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.7" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 4.3" 4" 0.3" 💧 Light watering
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 Light watering
Oct 4.3" 1.8" 2.5" 🚿 Regular watering
Nov 1.1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Bon Homme County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Scallions 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.

Scallions needs ~690 GDD — county provides 1,817 GDD Excellent fit

Scallions Planting Timeline — Bon Homme County, SD

Scallions Planting Calendar

Activity When Date Range
Start Indoors March 27 Mar 27 – Apr 10
Transplant Outdoors May 1 May 1 – May 15
Direct Sow April 17 Apr 17 – May 8
Harvest June 26 Jun 26 – Jul 24
Fall Sowing July 28 Jul 28 – Aug 11

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

158 days in Bon Homme County

Growing Tips for Scallions in Bon Homme County

Direct sow Scallions outdoors after May 01 in Bon Homme County when soil has warmed and frost danger has passed.

Common pests for Scallions in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow every 3 weeks for continuous harvest. Thin to 1 inch apart or grow in clusters. Harvest when pencil-thick by pulling or cutting at soil level.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Scallions in Bon Homme County, SD?

Bon Homme County is in Zone 5a with an average last frost of May 1. Plan your Scallions planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bon Homme County, SD?

Bon Homme County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is May 1 and first fall frost is October 6.

🌱

Your Bon Homme County Garden Planner — Free

A 24-page printable planner built for Bon Homme 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 Bon Homme 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.