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When to Plant Bok Choy in Ashland County, WI

Ashland County, Wisconsin Zone 4a May

Your May gardening checklist

Here's what deserves your attention in Ashland County, Wisconsin this month. Everything below is tailored to Zone 4a and timed around your local frost dates.

Avg. last frost May 20
Avg. first frost September 27
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Get bok choy in the ground

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

  2. Direct-sow bok choy

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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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.

Ashland County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 20 and the first fall frost is September 27, giving you a growing season of approximately 130 days.

At an elevation of 705 feet, Ashland County receives approximately 30.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Bok Choy to ensure they mature before fall.

Ashland County, WI (Zone 4a) Short season
130 days
Last Spring Frost May 20
130 growing days
First Fall Frost September 27

Ashland County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jun 28 – Aug 2
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jul 1 – Aug 5
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Apr 23 Transplant: Jun 4 🍅 Harvest: Jul 16 – Aug 20

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 Ashland County

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

Soil pH

Your soil pH (6.0–7.0) is within Bok Choy's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.9%) — 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

3
successive plantings in your 130-day season

Sow every 4.6 weeks. Last sowing by Jul 29 to harvest before frost.

For a dedicated fall crop, sow by Jul 05.

Plant Water Budget

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

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 1.3" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 3" 3.8" 0" ✅ Rainfall sufficient
Jun 3" 3.8" 0" ✅ Rainfall sufficient
Jul 3" 2.9" 0.1" 💧 Light watering
Aug 3" 3.6" 0" ✅ Rainfall sufficient
Sep 3" 2.3" 0.7" 💧 Light watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Ashland 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 ~462 GDD — county provides 1,202 GDD Excellent fit

Bok Choy Planting Timeline — Ashland County, WI

Bok Choy Planting Calendar

Activity When Date Range
Start Indoors April 8 Apr 8 – Apr 22
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 13 May 13 – Jun 3
Harvest July 1 Jul 1 – Aug 5
Fall Sowing July 5 Jul 5 – Jul 19

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

Month-by-Month Timeline

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

130 days in Ashland County

Growing Tips for Bok Choy in Ashland County

Direct sow Bok Choy outdoors after May 20 in Ashland 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 Ashland County, WI?

Ashland County is in Zone 4a with an average last frost of May 20. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ashland County, WI?

Ashland County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 20 and first fall frost is September 27.

🌱

Your Ashland County Garden Planner — Free

A 24-page printable planner built for Ashland 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Ashland County, WI. 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.