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When to Plant Onion in Harrison County, MS

Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

Harrison County, Mississippi is in USDA Zone 8b. The average last spring frost is March 4 and the first fall frost is November 26, giving you a growing season of approximately 267 days.

At an elevation of 190 feet, Harrison County receives approximately 53 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96ยฐF, so Onion may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Onion will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.

Harrison County, MS (Zone 8b) Long season
267 days
Last Spring Frost March 4
267 growing days
First Fall Frost November 26

Harrison County Soil Profile

Soil Type

Sandy Loam

Soil pH

4.8-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (131 days to spare)
Start indoors: Jan 14 Transplant: Feb 18 🍅 Harvest: May 20 – Jul 8
Recommended (50%) ✓ Fits season (127 days to spare)
Start indoors: Jan 28 Transplant: Mar 4 🍅 Harvest: Jun 3 – Jul 22
Safe Start (90%) ✓ Fits season (126 days to spare)
Start indoors: Feb 19 Transplant: Mar 26 🍅 Harvest: Jun 25 – Aug 13

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
1.0″/week
Rainfall provides
0.8″/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

Onion needs ~2,310 GDD — county provides 5,874 GDD Excellent fit

Onion Planting Timeline โ€” Harrison County, MS

Onion Planting Calendar

Activity When Date Range
Start Indoors January 28 Jan 28 โ€“ Feb 11
Transplant Outdoors March 4 Mar 4 โ€“ Mar 18
Direct Sow February 18 Feb 18 โ€“ Mar 11
Fall Sowing September 17 Sep 17 โ€“ Oct 1
Harvest June 3 Jun 3 โ€“ Jul 22

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 8b

Growing Season

267 days

Growing Tips for Harrison County

Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

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Frequently Asked Questions

When should I plant Onion in Harrison County, MS?

Harrison County is in Zone 8b with an average last frost of March 4. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Harrison County, MS?

Harrison County, Mississippi is in USDA Hardiness Zone 8b. The average last spring frost is March 4 and first fall frost is November 26.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Harrison County gardeners in Zone 8b 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, MS. Local conditions may vary. Last updated: April 2026.