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When to Plant Acorn Squash in Sullivan County, IN

Sullivan County, Indiana Zone 6b May

Your May game plan for Sullivan County, Indiana

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

Avg. last frost April 18
Avg. first frost October 17
Soil temp (4") 62°F
Watering Moderate
Pest pressure Low
Daylight 14.1 hrs
  1. Move acorn squash into the garden

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Sow acorn squash in trays indoors

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

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Acorn squash is a small winter squash with dark green, ribbed skin and mildly sweet orange flesh. It is perfect for stuffing and roasting as individual servings.

Sullivan County, Indiana is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 17, giving you a growing season of approximately 182 days.

At an elevation of 914 feet, Sullivan County receives approximately 34.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Acorn Squash during the growing season.

Sullivan County, IN (Zone 6b) Moderate season
182 days
Last Spring Frost April 18
182 growing days
First Fall Frost October 17

Sullivan County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Mar 9 Transplant: Apr 27 🍅 Harvest: Jul 20 – Aug 24
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Mar 14 Transplant: May 2 🍅 Harvest: Jul 25 – Aug 29
Safe Start (90%) ✓ Fits season (46 days to spare)
Start indoors: Mar 30 Transplant: May 18 🍅 Harvest: Aug 10 – Sep 14

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 Sullivan County

How your county's soil matches Acorn Squash's growing requirements.

Soil pH

Your soil pH (6.0–7.0) is within Acorn Squash's preferred range (5.5–7.0).

Soil Texture

The silt loam soil in Sullivan County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.5%) — Acorn Squash will thrive.

How to Plant Acorn Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Acorn Squash

2
successive plantings in your 182-day season

Sow every 9.1 weeks. Last sowing by Jul 09 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 488 gal / 100 sq ft

Monthly Watering Guide for Acorn Squash

Acorn Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Acorn Squash Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 4.8" 3.2" 1.6" 💧 Light watering
May 4.8" 3.6" 1.2" 💧 Light watering
Jun 4.8" 4.9" 0" ✅ Rainfall sufficient
Jul 4.8" 3.5" 1.3" 💧 Light watering
Aug 4.8" 4" 0.8" 💧 Light watering
Sep 4.8" 2.9" 1.9" 💧 Light watering
Oct 4.8" 2.8" 2" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Acorn Squash 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.

Acorn Squash needs ~1,575 GDD — county provides 3,185 GDD Excellent fit

Acorn Squash Planting Timeline — Sullivan County, IN

Acorn Squash Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors May 2 May 2 – May 16
Direct Sow April 25 Apr 25 – May 16
Harvest July 25 Jul 25 – Aug 29

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 1-2 times/week

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

182 days in Sullivan County

Growing Tips for Acorn Squash in Sullivan County

Direct sow Acorn Squash outdoors after April 18 in Sullivan County when soil has warmed and frost danger has passed.

Common pests for Acorn Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost. Harvest when the ground spot turns orange and the skin is hard. Acorn squash has a shorter storage life than butternut, lasting about 2 months.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Acorn Squash in Sullivan County, IN?

Sullivan County is in Zone 6b with an average last frost of April 18. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sullivan County, IN?

Sullivan County, Indiana is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 17.

🌱

Your Sullivan County Garden Planner — Free

A 24-page printable planner built for Sullivan County (Zone 6b). 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 Sullivan County, IN. 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.