Blog

When to Plant Begonias in Harmon County, OK

Harmon County, Oklahoma Zone 7b June

Harmon County, Oklahoma gardeners: here's your June plan

Welcome to June in Zone 7b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost March 31
Avg. first frost November 5
Soil temp (4") 76°F
Watering Low
Pest pressure High
Daylight 14.3 hrs
  1. Indoor seed-starting week for begonias

    Label every cell. You will absolutely forget which is which otherwise.

  2. It's harvest week for begonias

    If you can't use it all right away, check the food-preservation section of your planner.

Before July arrives, get these ready
  • First harvests: begonias

Instant PDF download. No spam, unsubscribe any time.

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.

Harmon County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 31 and the first fall frost is November 5, giving you a growing season of approximately 219 days.

At an elevation of 993 feet, Harmon County receives approximately 34.4 inches of rainfall annually with predominantly loam soil. Summer highs average 91°F, providing good warmth for Begonias during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Deer-resistant
Harmon County, OK (Zone 7b) Long season
219 days
Last Spring Frost March 31
219 growing days
First Fall Frost November 5
Share this guide:

Harmon County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.5

Drainage

Well Drained

Begonias Planting Risk Windows

Early Start (70% safe) ✓ Fits season (23 days to spare)
Start indoors: Jan 12 Transplant: Mar 23 🌸 Bloom: Jun 1 – Oct 5
Recommended (50%) ✓ Fits season (23 days to spare)
Start indoors: Jan 20 Transplant: Mar 31 🌸 Bloom: Jun 9 – Oct 13
Safe Start (90%) ✓ Fits season (23 days to spare)
Start indoors: Feb 4 Transplant: Apr 15 🌸 Bloom: Jun 24 – Oct 28

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 Harmon County

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

Soil pH

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

Soil Texture

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

Organic Matter

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

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 07 to harvest before frost.

Begonias Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 796 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 0.9" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 4.3" 2.3" 2" 💧 Light watering
Apr 4.3" 3.7" 0.6" 💧 Light watering
May 4.3" 5.1" 0" ✅ Rainfall sufficient
Jun 4.3" 5" 0" ✅ Rainfall sufficient
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 4.8" 0" ✅ Rainfall sufficient
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 2" 2.3" 🚿 Regular watering
Nov 4.3" 1.3" 3" 🚿 Regular watering
Dec 1" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Harmon 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 ~1,460 GDD — county provides 3,996 GDD Excellent fit

Begonias Planting Timeline — Harmon County, OK

Begonias Planting Calendar

Activity When Date Range
Start Indoors January 20 Jan 20 – Feb 3
Transplant Outdoors March 31 Mar 31 – Apr 14
Bloom June 9 Jun 9 – Oct 13

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

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 7b

📆 Growing Season

219 days in Harmon County

Growing Tips for Begonias in Harmon County

Direct sow Begonias outdoors after March 31 in Harmon 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 Harmon County, OK?

Harmon County is in Zone 7b with an average last frost of March 31. Plan your Begonias planting based on this frost date — see the calendar above for exact timing.

What planting zone is Harmon County, OK?

Harmon County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 31 and first fall frost is November 5.

🌱

Your Harmon County Garden Planner — Free

A 22-page printable planner built for Harmon County (Zone 7b). 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 Harmon 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.