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When to Plant Zinnia in Stark County, OH

Stark County, Ohio Zone 6b July

Your July planting checklist for Stark County, Ohio

A quick July briefing for Stark County, Ohio gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 30
Avg. first frost October 18
Soil temp (4") 75°F
Watering Moderate
Pest pressure High
Daylight 14.7 hrs
  1. Start harvesting zinnia

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

Coming up in August — start thinking about
  • First harvests: zinnia

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Zinnia (Zinnia elegans) is a fast-growing, heat-loving annual that produces bold, dahlia-like blooms from early summer until hard frost. One of the easiest flowers to grow from direct-sown seed, zinnias thrive in hot, dry conditions and are magnets for butterflies and beneficial insects. They make excellent companion plants alongside marigolds in the vegetable garden.

Stark County, Ohio is in USDA Zone 6b. The average last spring frost is April 30 and the first fall frost is October 18, giving you a growing season of approximately 171 days.

At an elevation of 1,118 feet, Stark County receives approximately 31.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Zinnia to ensure they mature before fall.

Annual Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Stark County, OH (Zone 6b) Moderate season
171 days
Last Spring Frost April 30
171 growing days
First Fall Frost October 18

Stark County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7

Drainage

Well Drained

Zinnia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (1 days to spare)
Start indoors: Mar 29 Transplant: Apr 26 🌸 Bloom: Jul 5 – Oct 11
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Apr 2 Transplant: Apr 30 🌸 Bloom: Jul 9 – Oct 15
Safe Start (90%) ✗ May not fit
Start indoors: Apr 24 Transplant: May 22 🌸 Bloom: Jul 31 – Nov 6

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 Stark County

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

Soil pH

Your soil pH (6.2–7.0) is within Zinnia's preferred range (5.5–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Zinnia.

How to Plant Zinnia

0.3"
Planting Depth
12"
Between Plants
18"
Between Rows

Succession Planting Zinnia

3
successive plantings in your 171-day season

Sow every 6.9 weeks. Last sowing by Aug 09 to harvest before frost.

Zinnia Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Zinnia

Zinnia 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 Zinnia Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2.2" 3.3" 0" ✅ Rainfall sufficient
May 2.2" 4.1" 0" ✅ Rainfall sufficient
Jun 2.2" 4" 0" ✅ Rainfall sufficient
Jul 2.2" 3.1" 0" ✅ Rainfall sufficient
Aug 2.2" 2.9" 0" ✅ Rainfall sufficient
Sep 2.2" 2.7" 0" ✅ Rainfall sufficient
Oct 2.2" 2.6" 0" ✅ Rainfall sufficient
Nov 2.1" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Zinnia 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.

Zinnia needs ~845 GDD — county provides 2,223 GDD Excellent fit

Zinnia Planting Timeline — Stark County, OH

Zinnia Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 30 Apr 30 – May 21
Bloom July 9 Jul 9 – Oct 15

Plant 0.3" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

171 days in Stark County

Growing Tips for Zinnia in Stark County

Direct sow Zinnia outdoors after April 30 in Stark County when soil has warmed and frost danger has passed.

Common pests for Zinnia 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 when soil reaches 60°F; seeds germinate in 5-7 days. In zones 3-5 a brief indoor start (4 weeks) is worthwhile but transplant carefully — zinnias dislike root disturbance. Deadhead frequently to extend bloom. Excellent cut flower; harvesting regularly encourages branching. Avoid overhead watering to reduce powdery mildew.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zinnia in Stark County, OH?

Stark County is in Zone 6b with an average last frost of April 30. Plan your Zinnia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Stark County, OH?

Stark County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 30 and first fall frost is October 18.

🌱

Your Stark County Garden Planner — Free

A 22-page printable planner built for Stark 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 Stark County, OH. Local conditions may vary. Last updated: July 2026.

Sources & credits

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