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When to Plant Brussels Sprouts in Gregory County, SD

Gregory County, South Dakota Zone 5a May

Your May planting checklist for Gregory County, South Dakota

Your garden in Gregory County, South Dakota is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 10
Avg. first frost October 6
Soil temp (4") 57°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Transplant brussels sprouts outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

Before June arrives, get these ready
  • Starting indoors: brussels sprouts

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Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.

Gregory County, South Dakota is in USDA Zone 5a. The average last spring frost is May 10 and the first fall frost is October 6, giving you a growing season of approximately 149 days.

At an elevation of 668 feet, Gregory County receives approximately 34.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Brussels Sprouts to ensure they mature before fall.

Gregory County, SD (Zone 5a) Short season
149 days
Last Spring Frost May 10
149 growing days
First Fall Frost October 6
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Gregory 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 (8 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jul 30 – Sep 24
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Aug 9 – Oct 4
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: Aug 18 – Oct 13

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 Gregory County

How your county's soil matches Brussels Sprouts's growing requirements.

Soil pH

Your soil pH (6.4–7.4) is within Brussels Sprouts's preferred range (6.0–7.5).

Soil Texture

The loam soil in Gregory County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.2%). Annual compost additions will help Brussels Sprouts.

How to Plant Brussels Sprouts

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Brussels Sprouts

Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Brussels Sprouts Needs Rainfall You Supplement Action
Jan 0.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 3.9" 5.8" 0" ✅ Rainfall sufficient
Jun 3.9" 5" 0" ✅ Rainfall sufficient
Jul 3.9" 4.8" 0" ✅ Rainfall sufficient
Aug 3.9" 4.1" 0" ✅ Rainfall sufficient
Sep 3.9" 3.3" 0.6" 💧 Light watering
Oct 3.9" 1.9" 2" 🚿 Regular watering
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

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

Brussels Sprouts 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.

Brussels Sprouts needs ~1,265 GDD — county provides 1,713 GDD Excellent fit

Brussels Sprouts Planting Timeline — Gregory County, SD

Brussels Sprouts Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow April 26 Apr 26 – May 17
Harvest August 9 Aug 9 – Oct 4
Fall Sowing July 28 Jul 28 – Aug 11

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Natural rainfall sufficient

📅 Days to Maturity

90–130 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

149 days in Gregory County

Growing Tips for Brussels Sprouts in Gregory County

Direct sow Brussels Sprouts outdoors after May 10 in Gregory County when soil has warmed and frost danger has passed.

Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Brussels Sprouts in Gregory County, SD?

Gregory County is in Zone 5a with an average last frost of May 10. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gregory County, SD?

Gregory County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is May 10 and first fall frost is October 6.

🌱

Your Gregory County Garden Planner — Free

A 24-page printable planner built for Gregory 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 Gregory 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.