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When to Plant Borage in Macomb County, MI

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.

Macomb County, Michigan is in USDA Zone 6a. The average last spring frost is April 28 and the first fall frost is October 20, giving you a growing season of approximately 175 days.

At an elevation of 628 feet, Macomb County receives approximately 33.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Borage during the growing season.

Macomb County, MI (Zone 6a) Moderate season
175 days
Last Spring Frost April 28
175 growing days
First Fall Frost October 20

Macomb County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (72 days to spare)
Start indoors: Mar 22 Transplant: Apr 19 🍅 Harvest: Jun 14 – Aug 2
Recommended (50%) ✓ Fits season (77 days to spare)
Start indoors: Mar 24 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 4
Safe Start (90%) ✓ Fits season (73 days to spare)
Start indoors: Apr 8 Transplant: May 6 🍅 Harvest: Jul 1 – Aug 19

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
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Borage needs ~1,004 GDD — county provides 3,193 GDD Excellent fit

Borage Planting Timeline โ€” Macomb County, MI

Borage Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 โ€“ Apr 7
Transplant Outdoors April 21 Apr 21 โ€“ May 5
Direct Sow April 14 Apr 14 โ€“ May 5
Fall Sowing August 11 Aug 11 โ€“ Aug 25
Harvest June 16 Jun 16 โ€“ Aug 4

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 Harvest
August Fall Sowing 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 6a

Growing Season

175 days

Growing Tips for Macomb 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 Macomb County, MI?

Macomb County is in Zone 6a with an average last frost of April 28. Plan your Borage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Macomb County, MI?

Macomb County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 28 and first fall frost is October 20.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Macomb County gardeners in Zone 6a 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 Macomb County, MI. Local conditions may vary. Last updated: April 2026.