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When to Plant Borage in Burnett County, WI

Burnett County, Wisconsin Zone 4a May

May in Burnett County, Wisconsin — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Burnett County, Wisconsin.

Avg. last frost May 15
Avg. first frost September 27
Soil temp (4") 50°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Plant out borage

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

  2. Plant borage from seed, right in the garden

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

To set up a strong June, finish these tasks
  • 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.

Burnett County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 27, giving you a growing season of approximately 135 days.

At an elevation of 574 feet, Burnett County receives approximately 30.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Borage to ensure they mature before fall.

Burnett County, WI (Zone 4a) Short season
135 days
Last Spring Frost May 15
135 growing days
First Fall Frost September 27

Burnett County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Mar 28 Transplant: May 2 🍅 Harvest: Jun 27 – Aug 15
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 3 – Aug 21
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: Apr 18 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 5

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 Burnett County

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

Soil pH

Your soil pH (6.2–7.3) overlaps with Borage's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Borage.

Organic Matter

Organic matter is excellent (4.6%) — 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 135-day season

Sow every 5.7 weeks. Last sowing by Jul 29 to harvest before frost.

For a dedicated fall crop, sow by Jul 05.

Plant Water Budget

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

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 1.4" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.6" 0" ❄️ Dormant
May 2.2" 3.6" 0" ✅ Rainfall sufficient
Jun 2.2" 4.2" 0" ✅ Rainfall sufficient
Jul 2.2" 3" 0" ✅ Rainfall sufficient
Aug 2.2" 3.6" 0" ✅ Rainfall sufficient
Sep 2.2" 2.7" 0" ✅ Rainfall sufficient
Oct 2.5" 0" ❄️ Dormant
Nov 2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Burnett 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 ~509 GDD — county provides 1,248 GDD Excellent fit

Borage Planting Timeline — Burnett County, WI

Borage Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 8 May 8 – May 22
Direct Sow May 8 May 8 – May 29
Harvest July 3 Jul 3 – Aug 21
Fall Sowing July 5 Jul 5 – Jul 19

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 4a

📆 Growing Season

135 days in Burnett County

Growing Tips for Borage in Burnett County

Direct sow Borage outdoors after May 15 in Burnett 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 Burnett County, WI?

Burnett County is in Zone 4a with an average last frost of May 15. Plan your Borage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Burnett County, WI?

Burnett County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 27.

🌱

Your Burnett County Garden Planner — Free

A 24-page printable planner built for Burnett 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 Burnett 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.