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When to Plant Borage in Bayfield County, WI

Bayfield County, Wisconsin Zone 4b May

This month in Bayfield County, Wisconsin

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

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. Time to transplant borage

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

  2. Scatter borage into prepared beds

    These tolerate cool soil, so you're not gambling by sowing now.

Before June arrives, get these ready
  • Starting indoors: borage

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Borage is a self-seeding annual herb with star-shaped blue flowers that attract pollinators. Its leaves have a cucumber-like flavor and the flowers are edible.

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 Borage 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

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) ✓ Fits season (42 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jun 25 – Aug 13
Recommended (50%) ✓ Fits season (44 days to spare)
Start indoors: Apr 2 Transplant: May 7 🍅 Harvest: Jul 2 – Aug 20
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Apr 20 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 7

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 Borage's growing requirements.

Soil pH

Your soil pH (5.8–6.8) overlaps with Borage's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Borage

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Succession Planting Borage

3
successive plantings in your 142-day season

Sow every 5.7 weeks. Last sowing by Aug 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 11.

Plant Water Budget

Plant needs
0.5″/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 Borage

Borage needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Borage 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 2.2" 4.4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.7" 0" ✅ Rainfall sufficient
Jul 2.2" 4.4" 0" ✅ Rainfall sufficient
Aug 2.2" 3.4" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 3.1" 0" ✅ Rainfall sufficient
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.

Borage 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.

Borage needs ~550 GDD — county provides 1,420 GDD Excellent fit

Borage Planting Timeline — Bayfield County, WI

Borage Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 7 May 7 – May 21
Direct Sow May 7 May 7 – May 28
Harvest July 2 Jul 2 – Aug 20
Fall Sowing July 11 Jul 11 – Jul 25

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

50–60 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

142 days in Bayfield County

Growing Tips for Borage in Bayfield County

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

General growing tips

Direct sow in spring as borage does not transplant well. Allow some plants to go to seed for next year. Young leaves are best; older leaves become bristly.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Borage in Bayfield County, WI?

Bayfield County is in Zone 4b with an average last frost of May 14. Plan your Borage 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.

🌱

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.