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When to Plant Bok Choy in Otter Tail County, MN

Otter Tail County, Minnesota Zone 4a May

May in Otter Tail County, Minnesota — your action list

Each item below is timed to Otter Tail County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 11
Avg. first frost September 28
Soil temp (4") 49°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Move bok choy from tray to bed

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Put bok choy seeds straight in the ground

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

June will be here before you know it — start on
  • Starting indoors: bok choy
  • First harvests: bok choy

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Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.

Otter Tail County, Minnesota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is September 28, giving you a growing season of approximately 140 days.

At an elevation of 571 feet, Otter Tail County receives approximately 40.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Bok Choy to ensure they mature before fall.

Otter Tail County, MN (Zone 4a) Short season
140 days
Last Spring Frost May 11
140 growing days
First Fall Frost September 28

Otter Tail County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (71 days to spare)
Start indoors: Mar 17 Transplant: Apr 28 🍅 Harvest: Jun 9 – Jul 14
Recommended (50%) ✓ Fits season (63 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jun 22 – Jul 27
Safe Start (90%) ✓ Fits season (69 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Jul 2 – 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 Otter Tail County

How your county's soil matches Bok Choy's growing requirements.

Soil pH

Your soil pH (6.3–6.8) is within Bok Choy's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Otter Tail County is excellent for Bok Choy — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Bok Choy is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.

Organic Matter

Organic matter is excellent (5.2%) — Bok Choy will thrive.

How to Plant Bok Choy

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Bok Choy

4
successive plantings in your 140-day season

Sow every 4.6 weeks. Last sowing by Jul 30 to harvest before frost.

For a dedicated fall crop, sow by Jul 06.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.2″/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 Bok Choy

Bok Choy needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Bok Choy Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 3" 4.2" 0" ✅ Rainfall sufficient
Jun 3" 5.7" 0" ✅ Rainfall sufficient
Jul 3" 5" 0" ✅ Rainfall sufficient
Aug 3" 4.3" 0" ✅ Rainfall sufficient
Sep 3" 3.1" 0" ✅ Rainfall sufficient
Oct 3.4" 0" ❄️ Dormant
Nov 2.8" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

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

Bok Choy 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.

Bok Choy needs ~500 GDD — county provides 1,400 GDD Excellent fit

Bok Choy Planting Timeline — Otter Tail County, MN

Bok Choy Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest June 22 Jun 22 – Jul 27
Fall Sowing July 6 Jul 6 – Jul 20

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

140 days in Otter Tail County

Growing Tips for Bok Choy in Otter Tail County

Direct sow Bok Choy outdoors after May 11 in Otter Tail County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow in spring or fall for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Bok Choy in Otter Tail County, MN?

Otter Tail County is in Zone 4a with an average last frost of May 11. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.

What planting zone is Otter Tail County, MN?

Otter Tail County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is September 28.

🌱

Your Otter Tail County Garden Planner — Free

A 24-page printable planner built for Otter Tail County (Zone 4a). 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 Otter Tail County, MN. 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.