Blog

When to Plant Sunflower in Fountain County, IN

Fountain County, Indiana Zone 5b April

Your April game plan for Fountain County, Indiana

Your Fountain County, Indiana garden is entering a new phase. Here's what's on the schedule for April and why each task matters now.

Avg. last frost April 16
Avg. first frost October 17
Soil temp (4") 44°F
Watering High
Pest pressure Low
Daylight 13.1 hrs
  1. Harden off and plant sunflower

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Plant sunflower from seed, right in the garden

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Instant PDF download. No spam, unsubscribe any time.

Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.

Fountain County, Indiana is in USDA Zone 5b. The average last spring frost is April 16 and the first fall frost is October 17, giving you a growing season of approximately 184 days.

At an elevation of 1,088 feet, Fountain County receives approximately 30.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Sunflower during the growing season.

Fountain County, IN (Zone 5b) Moderate season
184 days
Last Spring Frost April 16
184 growing days
First Fall Frost October 17

Fountain County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Feb 16 Transplant: Apr 27 🍅 Harvest: Jul 6 – Aug 24
Recommended (50%) ✓ Fits season (51 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jul 9 – Aug 27
Safe Start (90%) ✓ Fits season (45 days to spare)
Start indoors: Mar 9 Transplant: May 18 🍅 Harvest: Jul 27 – 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 Fountain County

How your county's soil matches Sunflower's growing requirements.

Soil pH

Your soil pH (6.1–7.2) is within Sunflower's preferred range (6.0–7.5).

Soil Texture

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

Drainage

Drainage is adequate for Sunflower.

Organic Matter

Organic matter is excellent (4.0%) — Sunflower will thrive.

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
30"
Between Rows

Succession Planting Sunflower

3
successive plantings in your 184-day season

Sow every 8 weeks. Last sowing by Jul 09 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Sunflower

Sunflower needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Sunflower Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.2" 2.6" 0" ✅ Rainfall sufficient
May 2.2" 3.4" 0" ✅ Rainfall sufficient
Jun 2.2" 4.3" 0" ✅ Rainfall sufficient
Jul 2.2" 3" 0" ✅ Rainfall sufficient
Aug 2.2" 3.3" 0" ✅ Rainfall sufficient
Sep 2.2" 2.6" 0" ✅ Rainfall sufficient
Oct 2.2" 2.6" 0" ✅ Rainfall sufficient
Nov 2.4" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Sunflower 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.

Sunflower needs ~1,169 GDD — county provides 2,530 GDD Excellent fit

Sunflower Planting Timeline — Fountain County, IN

Sunflower Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 – Mar 5
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 23 Apr 23 – May 14
Harvest July 9 Jul 9 – Aug 27

Plant 1" deep · 18" apart · Rows 30" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors 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

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

184 days in Fountain County

Growing Tips for Sunflower in Fountain County

Direct sow Sunflower outdoors after April 16 in Fountain County when soil has warmed and frost danger has passed.

Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sunflower in Fountain County, IN?

Fountain County is in Zone 5b with an average last frost of April 16. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fountain County, IN?

Fountain County, Indiana is in USDA Hardiness Zone 5b. The average last spring frost is April 16 and first fall frost is October 17.

🌱

Your Fountain County Garden Planner — Free

A 24-page printable planner built for Fountain County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Fountain County, IN. Local conditions may vary. Last updated: April 2026.

Sources & credits

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