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When to Plant Borage in Benton County, MN

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.

Benton County, Minnesota is in USDA Zone 4a. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.

At an elevation of 1,178 feet, Benton County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Borage to ensure they mature before fall.

Benton County, MN (Zone 4a) Moderate season
157 days
Last Spring Frost May 2
157 growing days
First Fall Frost October 6

Benton County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 15 Transplant: Apr 19 🍅 Harvest: Jun 14 – Aug 2
Recommended (50%) ✓ Fits season (59 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jun 20 – Aug 8
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jul 7 – Aug 25

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.

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
Borage needs ~715 GDD — county provides 2,041 GDD Excellent fit

Borage Planting Timeline โ€” Benton County, MN

Borage Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 โ€“ Apr 4
Transplant Outdoors April 25 Apr 25 โ€“ May 9
Direct Sow April 25 Apr 25 โ€“ May 16
Fall Sowing July 14 Jul 14 โ€“ Jul 28
Harvest June 20 Jun 20 โ€“ Aug 8

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

50โ€“60 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

157 days

Growing Tips for Benton County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Borage in Benton County, MN?

Benton County is in Zone 4a with an average last frost of May 2. Plan your Borage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Benton County, MN?

Benton County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 2 and first fall frost is October 6.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Benton County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

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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 Benton County, MN. Local conditions may vary. Last updated: April 2026.