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When to Plant Sweet Corn in Newport County, RI

Newport County, Rhode Island Zone 7a May

Top priorities for Newport County, Rhode Island gardeners in May

We've pulled the most time-sensitive tasks for Newport County, Rhode Island this May and put them front and centre. Tackle them in order.

Avg. last frost April 30
Avg. first frost October 13
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 14.3 hrs
  1. Seed sweet corn outdoors

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

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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.

Newport County, Rhode Island is in USDA Zone 7a. The average last spring frost is April 30 and the first fall frost is October 13, giving you a growing season of approximately 166 days.

At an elevation of 441 feet, Newport County receives approximately 41.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 94°F, providing good warmth for Sweet Corn during the growing season.

Newport County, RI (Zone 7a) Moderate season
166 days
Last Spring Frost April 30
166 growing days
First Fall Frost October 13
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Newport County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (62 days to spare)
Transplant: Apr 24 🍅 Harvest: Jun 26 – Aug 7
Recommended (50%) ✓ Fits season (61 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 2 – Aug 13
Safe Start (90%) ✓ Fits season (64 days to spare)
Transplant: May 15 🍅 Harvest: Jul 17 – Aug 28

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 Newport County

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

Soil pH

Your soil pH (4.8–6.7) is more acidic than Sweet Corn prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Newport County is excellent for Sweet Corn — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.8%). 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

3
successive plantings in your 166-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.1″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 650 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 2.8" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 3.8" 0" ❄️ Dormant
Apr 6.5" 3.3" 3.2" 💧 Light watering
May 6.5" 4.1" 2.4" 💧 Light watering
Jun 6.5" 4.5" 2" 💧 Light watering
Jul 6.5" 4.1" 2.4" 💧 Light watering
Aug 6.5" 3.9" 2.6" 💧 Light watering
Sep 6.5" 3.3" 3.2" 💧 Light watering
Oct 6.5" 3.2" 3.3" 🚿 Regular watering
Nov 3.1" 0" ❄️ Dormant
Dec 3.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Newport 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 ~1,538 GDD — county provides 3,403 GDD Excellent fit

Sweet Corn Planting Timeline — Newport County, RI

Sweet Corn Planting Calendar

Activity When Date Range
Direct Sow May 7 May 7 – May 28
Harvest July 9 Jul 9 – Aug 20

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

166 days in Newport County

Growing Tips for Sweet Corn in Newport County

Direct sow Sweet Corn outdoors after April 30 in Newport County when soil has warmed and frost danger has passed.

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 Newport County, RI?

Newport County is in Zone 7a with an average last frost of April 30. Plan your Sweet Corn planting based on this frost date — see the calendar above for exact timing.

What planting zone is Newport County, RI?

Newport County, Rhode Island is in USDA Hardiness Zone 7a. The average last spring frost is April 30 and first fall frost is October 13.

🌱

Your Newport County Garden Planner — Free

A 24-page printable planner built for Newport County (Zone 7a). 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 Newport County, RI. 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.