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When to Plant Leeks in Sumter County, SC

Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Sumter County, South Carolina is in USDA Zone 8a. The average last spring frost is March 20 and the first fall frost is November 15, giving you a growing season of approximately 240 days.

At an elevation of 163 feet, Sumter County receives approximately 59.6 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 97ยฐF, so Leeks may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Leeks will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Leeks root diseases.

Sumter County, SC (Zone 8a) Long season
240 days
Last Spring Frost March 20
240 growing days
First Fall Frost November 15

Sumter County Soil Profile

Soil Type

Sandy Loam

Soil pH

4.9-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (74 days to spare)
Start indoors: Feb 2 Transplant: Mar 9 🍅 Harvest: Jun 8 – Aug 24
Recommended (50%) ✓ Fits season (72 days to spare)
Start indoors: Feb 13 Transplant: Mar 20 🍅 Harvest: Jun 19 – Sep 4
Safe Start (90%) ✓ Fits season (71 days to spare)
Start indoors: Feb 26 Transplant: Apr 2 🍅 Harvest: Jul 2 – Sep 17

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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Leeks needs ~2,730 GDD — county provides 5,460 GDD Excellent fit

Leeks Planting Timeline โ€” Sumter County, SC

Leeks Planting Calendar

Activity When Date Range
Start Indoors February 13 Feb 13 โ€“ Feb 27
Transplant Outdoors March 20 Mar 20 โ€“ Apr 3
Direct Sow March 6 Mar 6 โ€“ Mar 27
Fall Sowing September 6 Sep 6 โ€“ Sep 20
Harvest June 19 Jun 19 โ€“ Sep 4

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“150 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 8a

Growing Season

240 days

Growing Tips for Sumter County

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

Level Up Your Garden

Frequently Asked Questions

When should I plant Leeks in Sumter County, SC?

Sumter County is in Zone 8a with an average last frost of March 20. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sumter County, SC?

Sumter County, South Carolina is in USDA Hardiness Zone 8a. The average last spring frost is March 20 and first fall frost is November 15.

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Plan Your Garden with Confidence

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