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When to Plant Pac Choi in Union County, SD

Union County, South Dakota Zone 5a May

May to-do list for Union County, South Dakota

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

Avg. last frost April 30
Avg. first frost October 5
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
Looking ahead to June
  • Starting indoors: pac choi
  • First harvests: pac choi

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Pac choi (baby bok choy) is a compact variety of Chinese cabbage with tender leaves and crisp stems. It grows quickly and is ideal for containers and small spaces.

Union County, South Dakota is in USDA Zone 5a. The average last spring frost is April 30 and the first fall frost is October 5, giving you a growing season of approximately 158 days.

At an elevation of 938 feet, Union County receives approximately 22.8 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Pac Choi during the growing season.

Union County, SD (Zone 5a) Moderate season
158 days
Last Spring Frost April 30
158 growing days
First Fall Frost October 5

Union County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (90 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Jun 4 – Jul 2
Recommended (50%) ✓ Fits season (88 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jun 11 – Jul 9
Safe Start (90%) ✓ Fits season (83 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jun 26 – Jul 24

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 Union County

How your county's soil matches Pac Choi's growing requirements.

Soil pH

Your soil pH (6.8–7.2) is within Pac Choi's preferred range (6.0–7.5).

Soil Texture

The loam soil in Union County is excellent for Pac Choi — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Pac Choi.

How to Plant Pac Choi

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

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

Succession Planting Pac Choi

4
successive plantings in your 158-day season

Sow every 4.6 weeks. Last sowing by Aug 11 to harvest before frost.

For a dedicated fall crop, sow by Jul 27.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,508 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Pac Choi

Pac Choi needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Pac Choi Needs Rainfall You Supplement Action
Jan 0.7" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 6.5" 2.8" 3.7" 🚿 Regular watering
May 6.5" 3.2" 3.3" 🚿 Regular watering
Jun 6.5" 3.7" 2.8" 💧 Light watering
Jul 6.5" 3.1" 3.4" 🚿 Regular watering
Aug 6.5" 2.4" 4.1" 🚿 Regular watering
Sep 6.5" 1.9" 4.6" 🚿 Regular watering
Oct 6.5" 1.5" 5" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

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

Pac Choi 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.

Pac Choi needs ~689 GDD — county provides 2,291 GDD Excellent fit

Pac Choi Planting Timeline — Union County, SD

Pac Choi Planting Calendar

Activity When Date Range
Start Indoors March 26 Mar 26 – Apr 9
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 16 Apr 16 – May 7
Harvest June 11 Jun 11 – Jul 9
Fall Sowing July 27 Jul 27 – Aug 10

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

40–55 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

158 days in Union County

Growing Tips for Pac Choi in Union County

Direct sow Pac Choi outdoors after April 30 in Union County when soil has warmed and frost danger has passed.

Your generous 158.0-day season in Union County allows multiple plantings of Pac Choi. Sow every 20.0 days for continuous harvest.

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

Union County receives only 23" of rain annually. Pac Choi needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Grows best in cool weather. Space 6 inches apart for baby pac choi. Harvest whole plants or cut outer leaves as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pac Choi in Union County, SD?

Union County is in Zone 5a with an average last frost of April 30. Plan your Pac Choi planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, SD?

Union County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is April 30 and first fall frost is October 5.

🌱

Your Union County Garden Planner — Free

A 24-page printable planner built for Union 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 Union 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.