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When to Plant Begonias in Clark County, OH

Clark County, Ohio Zone 6a June

Your June planting checklist for Clark County, Ohio

Each item below is timed to Clark County, Ohio's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 18
Avg. first frost October 21
Soil temp (4") 72°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Sow begonias in trays indoors

    These need a head start before your last frost (April 18). Sow into cells now so you're ready to transplant in a few weeks.

Coming up in July — start thinking about
  • First harvests: begonias

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Wax begonias (Begonia × semperflorens) are the workhorse shade bedding plant of American horticulture, offering continuous bloom from transplant to hard frost. Bronze or green-leaved varieties perform well from deep shade to full sun (in northern zones) and tolerate summer humidity better than most cool- season flowers. A staple of mass plantings, containers, and window boxes.

Clark County, Ohio is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 21, giving you a growing season of approximately 186 days.

At an elevation of 721 feet, Clark County receives approximately 34.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Begonias during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Clark County, OH (Zone 6a) Moderate season
186 days
Last Spring Frost April 18
186 growing days
First Fall Frost October 21

Clark County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.1

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✓ Fits season (20 days to spare)
Start indoors: Jan 31 Transplant: Apr 18 🌸 Bloom: Jun 27 – Sep 26
Recommended (50%) ✓ Fits season (18 days to spare)
Start indoors: Feb 7 Transplant: Apr 25 🌸 Bloom: Jul 4 – Oct 3
Safe Start (90%) ✓ Fits season (10 days to spare)
Start indoors: Feb 28 Transplant: May 16 🌸 Bloom: Jul 25 – Oct 24

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 Clark County

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

Soil pH

Your soil pH (6.0–7.1) is more alkaline than Begonias prefers (5.5–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Begonias.

Organic Matter

Organic matter is excellent (4.3%) — Begonias will thrive.

How to Plant Begonias

8"
Between Plants
10"
Between Rows

Succession Planting Begonias

3
successive plantings in your 186-day season

Sow every 8 weeks. Last sowing by Jul 23 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 851 gal / 100 sq ft

Monthly Watering Guide for Begonias

Begonias needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Begonias Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

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

Begonias 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.

Begonias needs ~1,280 GDD — county provides 2,976 GDD Excellent fit

Begonias Planting Timeline — Clark County, OH

Begonias Planting Calendar

Activity When Date Range
Start Indoors February 7 Feb 7 – Feb 21
Transplant Outdoors April 25 Apr 25 – May 9
Bloom July 4 Jul 4 – Oct 3

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

186 days in Clark County

Growing Tips for Begonias in Clark County

Direct sow Begonias outdoors after April 18 in Clark County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors 10–12 weeks before last frost — seed is dust-fine; surface-sow on moist mix under lights, do not cover. Bottom heat (70–75°F) speeds germination. Transplant after frost; begonias are not direct-sown in practice. Pinch seedlings once for branching. Keep soil evenly moist; avoid waterlogged conditions. Bronze-leaf types tolerate more sun; green- leaf types prefer shade to part-sun.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Begonias in Clark County, OH?

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

What planting zone is Clark County, OH?

Clark County, Ohio is in USDA Hardiness Zone 6a. The average last spring frost is April 18 and first fall frost is October 21.

🌱

Your Clark County Garden Planner — Free

A 22-page printable planner built for Clark County (Zone 6a). 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 Clark County, OH. Local conditions may vary. Last updated: June 2026.

Sources & credits

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