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When to Plant Sweet Corn in Jasper County, SC

Jasper County, South Carolina Zone 9a May

Top priorities for Jasper County, South Carolina gardeners in May

A quick May briefing for Jasper County, South Carolina gardeners — what's urgent, what's next, and what can wait.

Avg. last frost March 15
Avg. first frost November 12
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.7 hrs
  1. Collect sweet corn at their peak

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Get ahead of June
  • First harvests: sweet corn

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Sweet corn is bred for high sugar content in its kernels, which convert to starch rapidly after harvest. Modern supersweet varieties hold their sweetness longer.

Jasper County, South Carolina is in USDA Zone 9a. The average last spring frost is March 15 and the first fall frost is November 12, giving you a growing season of approximately 242 days.

At an elevation of 143 feet, Jasper County receives approximately 60.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 97°F, so Sweet Corn may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Sweet Corn will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sweet Corn root diseases.

Jasper County, SC (Zone 9a) Long season
242 days
Last Spring Frost March 15
242 growing days
First Fall Frost November 12
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Jasper 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 (140 days to spare)
Transplant: Mar 6 🍅 Harvest: May 8 – Jun 19
Recommended (50%) ✓ Fits season (137 days to spare)
Transplant: Mar 15 🍅 Harvest: May 17 – Jun 28
Safe Start (90%) ✓ Fits season (132 days to spare)
Transplant: Apr 9 🍅 Harvest: Jun 11 – Jul 23

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.

Soil Compatibility in Jasper County

How your county's soil matches Sweet Corn's growing requirements.

Soil pH

Your soil pH (4.8–6.2) is more acidic than Sweet Corn prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Jasper County warms quickly in spring but drains fast. Sweet Corn will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Sweet Corn.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Sweet Corn.

How to Plant Sweet Corn

1"
Planting Depth
12"
Between Plants
36"
Between Rows

Succession Planting Sweet Corn

4
successive plantings in your 242-day season

Sow every 6.9 weeks. Last sowing by Aug 14 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 15 gal / 100 sq ft

Monthly Watering Guide for Sweet Corn

Sweet Corn needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Sweet Corn Needs Rainfall You Supplement Action
Jan 4.6" 0" ❄️ Dormant
Feb 4.8" 0" ❄️ Dormant
Mar 6.5" 5.7" 0.8" 💧 Light watering
Apr 6.5" 4.3" 2.2" 💧 Light watering
May 6.5" 5.5" 1" 💧 Light watering
Jun 6.5" 5.2" 1.3" 💧 Light watering
Jul 6.5" 5.8" 0.7" 💧 Light watering
Aug 6.5" 5.1" 1.4" 💧 Light watering
Sep 6.5" 5" 1.5" 💧 Light watering
Oct 6.5" 3.5" 3" 💧 Light watering
Nov 6.5" 5.3" 1.2" 💧 Light watering
Dec 5.2" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Jasper County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Sweet Corn Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Sweet Corn needs ~1,706 GDD — county provides 5,505 GDD Excellent fit

Sweet Corn Planting Timeline — Jasper County, SC

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow March 22 Mar 22 – Apr 12
Harvest May 24 May 24 – Jul 5

Plant 1" deep · 12" apart · Rows 36" apart

Month-by-Month Timeline

MonthActivities
January
February
March Direct Sow
April Direct Sow
May Harvest
June Harvest
July Harvest
August
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

242 days in Jasper County

Growing Tips for Sweet Corn in Jasper County

Direct sow Sweet Corn outdoors after March 15 in Jasper County when soil has warmed and frost danger has passed.

Sandy soil in Jasper County dries quickly — mulch Sweet Corn with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 97°F in Jasper County, provide afternoon shade for Sweet Corn and water deeply in the morning.

Common pests for Sweet Corn in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant in blocks of at least 4 rows for wind pollination. Direct sow after soil is warm. Isolate supersweet varieties from other corn types to prevent cross-pollination.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sweet Corn in Jasper County, SC?

Jasper County is in Zone 9a with an average last frost of March 15. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jasper County, SC?

Jasper County, South Carolina is in USDA Hardiness Zone 9a. The average last spring frost is March 15 and first fall frost is November 12.

🌱

Your Jasper County Garden Planner — Free

A 24-page printable planner built for Jasper County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Jasper County, SC. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.