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When to Plant Begonias in Carter County, OK

Carter County, Oklahoma Zone 8a June

Your June gardening checklist

Welcome to June in Zone 8a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost March 28
Avg. first frost November 2
Soil temp (4") 80°F
Watering Low
Pest pressure High
Daylight 14.3 hrs
  1. Indoor seed-starting week for begonias

    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.

  2. Start harvesting begonias

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Before July arrives, get these ready
  • 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.

Carter County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 28 and the first fall frost is November 2, giving you a growing season of approximately 219 days.

At an elevation of 648 feet, Carter County receives approximately 34.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Begonias during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Carter County, OK (Zone 8a) Long season
219 days
Last Spring Frost March 28
219 growing days
First Fall Frost November 2

Carter County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.5

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✓ Fits season (18 days to spare)
Start indoors: Jan 10 Transplant: Mar 14 🌸 Bloom: May 23 – Oct 10
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Jan 17 Transplant: Mar 21 🌸 Bloom: May 30 – Oct 17
Safe Start (90%) ✓ Fits season (17 days to spare)
Start indoors: Feb 6 Transplant: Apr 10 🌸 Bloom: Jun 19 – 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 Carter County

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

Soil pH

Your soil pH (6.4–7.5) is more alkaline than Begonias prefers (5.5–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Begonias.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Begonias.

How to Plant Begonias

8"
Between Plants
10"
Between Rows

Succession Planting Begonias

3
successive plantings in your 219-day season

Sow every 8 weeks. Last sowing by Aug 04 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,507 gal / 100 sq ft
Drought risk

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

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 0.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 4.3" 1.9" 2.4" 🚿 Regular watering
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 5.8" 0" ✅ Rainfall sufficient
Jun 4.3" 6" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 4.3" 1.2" 3.1" 🚿 Regular watering
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Carter 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 ~1,580 GDD — county provides 4,325 GDD Excellent fit

Begonias Planting Timeline — Carter County, OK

Begonias Planting Calendar

Activity When Date Range
Start Indoors January 17 Jan 17 – Jan 31
Transplant Outdoors March 21 Mar 21 – Apr 4
Bloom May 30 May 30 – Oct 17

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 8a

📆 Growing Season

219 days in Carter County

Growing Tips for Begonias in Carter County

Direct sow Begonias outdoors after March 28 in Carter 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 Carter County, OK?

Carter County is in Zone 8a with an average last frost of March 28. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carter County, OK?

Carter County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 28 and first fall frost is November 2.

🌱

Your Carter County Garden Planner — Free

A 22-page printable planner built for Carter County (Zone 8a). 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 Carter County, OK. 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.