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When to Plant Borage in McHenry County, IL

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.

McHenry County, Illinois is in USDA Zone 5a. The average last spring frost is April 18 and the first fall frost is October 20, giving you a growing season of approximately 185 days.

At an elevation of 640 feet, McHenry County receives approximately 39.4 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.

McHenry County, IL (Zone 5a) Moderate season
185 days
Last Spring Frost April 18
185 growing days
First Fall Frost October 20

McHenry County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (83 days to spare)
Start indoors: Mar 9 Transplant: Apr 6 🍅 Harvest: Jun 1 – Jul 20
Recommended (50%) ✓ Fits season (87 days to spare)
Start indoors: Mar 14 Transplant: Apr 11 🍅 Harvest: Jun 6 – Jul 25
Safe Start (90%) ✓ Fits season (86 days to spare)
Start indoors: Mar 30 Transplant: Apr 27 🍅 Harvest: Jun 22 – Aug 10

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
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Borage needs ~715 GDD — county provides 2,405 GDD Excellent fit

Borage Planting Timeline โ€” McHenry County, IL

Borage Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 โ€“ Mar 28
Transplant Outdoors April 11 Apr 11 โ€“ Apr 25
Direct Sow April 4 Apr 4 โ€“ Apr 25
Fall Sowing August 11 Aug 11 โ€“ Aug 25
Harvest June 6 Jun 6 โ€“ Jul 25

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Transplant Outdoors Direct Sow
May โ€”
June Harvest
July Harvest
August Fall Sowing
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 5a

Growing Season

185 days

Growing Tips for McHenry 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 McHenry County, IL?

McHenry County is in Zone 5a with an average last frost of April 18. Plan your Borage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is McHenry County, IL?

McHenry County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 18 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 McHenry County gardeners in Zone 5a 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 McHenry County, IL. Local conditions may vary. Last updated: April 2026.