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When to Plant Sunchoke in Bayfield County, WI

Bayfield County, Wisconsin Zone 4b May

Bayfield County, Wisconsin gardeners: here's your May plan

Your Bayfield County, Wisconsin garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 14
Avg. first frost October 3
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Move sunchoke into the garden

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

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Sunchokes (Jerusalem artichokes) are a native sunflower relative grown for their knobby, nutty-flavored tubers. They are extremely productive and nearly impossible to eradicate.

Bayfield County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 14 and the first fall frost is October 3, giving you a growing season of approximately 142 days.

At an elevation of 619 feet, Bayfield County receives approximately 36.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Sunchoke to ensure they mature before fall.

Bayfield County, WI (Zone 4b) Short season
142 days
Last Spring Frost May 14
142 growing days
First Fall Frost October 3
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Bayfield County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 21 🍅 Harvest: Sep 10 – Oct 15
Recommended (50%) ✗ May not fit
Transplant: May 28 🍅 Harvest: Sep 17 – Oct 22
Safe Start (90%) ✗ May not fit
Transplant: Jun 15 🍅 Harvest: Oct 5 – Nov 9

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 Bayfield County

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

Soil pH

Your soil pH (5.8–6.8) overlaps with Sunchoke's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Sunchoke

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/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 Sunchoke

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

Month Sunchoke Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Sunchoke 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.

Sunchoke needs ~1,300 GDD — county provides 1,420 GDD Good fit

Sunchoke Planting Timeline — Bayfield County, WI

Sunchoke Planting Calendar

Activity When Date Range
Transplant Outdoors May 28 May 28 – Jun 11
Harvest September 17 Sep 17 – Oct 22

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June Transplant Outdoors
July
August
September Harvest
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

110–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

142 days in Bayfield County

Growing Tips for Sunchoke in Bayfield County

Direct sow Sunchoke outdoors after May 14 in Bayfield County when soil has warmed and frost danger has passed.

Your 142.0-day growing season in Bayfield County is tight for Sunchoke (110.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Sunchoke in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant tubers 4 inches deep in early spring. Contain plants with barriers as they spread aggressively. Harvest after frost or leave in ground and dig as needed through winter.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunchoke in Bayfield County, WI?

Bayfield County is in Zone 4b with an average last frost of May 14. Plan your Sunchoke planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bayfield County, WI?

Bayfield County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 14 and first fall frost is October 3.

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Your Bayfield County Garden Planner — Free

A 24-page printable planner built for Bayfield County (Zone 4b). 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 Bayfield 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.