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When to Plant Borage in Harrison County, MO

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.

Harrison County, Missouri is in USDA Zone 5b. The average last spring frost is April 19 and the first fall frost is October 15, giving you a growing season of approximately 179 days.

At an elevation of 1,349 feet, Harrison County receives approximately 37.7 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.

Harrison County, MO (Zone 5b) Moderate season
179 days
Last Spring Frost April 19
179 growing days
First Fall Frost October 15

Harrison County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (81 days to spare)
Start indoors: Mar 9 Transplant: Apr 6 🍅 Harvest: Jun 1 – Jul 20
Recommended (50%) ✓ Fits season (81 days to spare)
Start indoors: Mar 15 Transplant: Apr 12 🍅 Harvest: Jun 7 – Jul 26
Safe Start (90%) ✓ Fits season (83 days to spare)
Start indoors: Mar 29 Transplant: Apr 26 🍅 Harvest: Jun 21 – Aug 9

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
Borage needs ~715 GDD — county provides 2,327 GDD Excellent fit

Borage Planting Timeline โ€” Harrison County, MO

Borage Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 โ€“ Mar 29
Transplant Outdoors April 12 Apr 12 โ€“ Apr 26
Direct Sow April 5 Apr 5 โ€“ Apr 26
Fall Sowing August 6 Aug 6 โ€“ Aug 20
Harvest June 7 Jun 7 โ€“ Jul 26

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 5b

Growing Season

179 days

Growing Tips for Harrison 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 Harrison County, MO?

Harrison County is in Zone 5b with an average last frost of April 19. Plan your Borage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Harrison County, MO?

Harrison County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 19 and first fall frost is October 15.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Harrison County gardeners in Zone 5b 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 Harrison County, MO. Local conditions may vary. Last updated: April 2026.