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When to Plant Lobelia in Dewey County, OK

Dewey County, Oklahoma Zone 7a July

July in Dewey County, Oklahoma — your action list

Your garden in Dewey County, Oklahoma is working on a schedule, even when you're not. Here's where you should be this July.

Avg. last frost April 13
Avg. first frost October 24
Soil temp (4") 84°F
Watering Moderate
Pest pressure High
Daylight 14.2 hrs
  1. Collect lobelia at their peak

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

August will be here before you know it — start on
  • First harvests: lobelia

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Lobelia (Lobelia erinus) is a cool-season annual prized for the intense cobalt blue that is rare among bedding flowers. It blooms most prolifically in spring and early summer but stalls or dies back during heat peaks above 90°F. In zones 3–7 it delivers a long display; in zones 8–9 it is best treated as a spring annual that fades by midsummer. Trailing types cascade beautifully from containers and window boxes.

Dewey County, Oklahoma is in USDA Zone 7a. The average last spring frost is April 13 and the first fall frost is October 24, giving you a growing season of approximately 194 days.

At an elevation of 745 feet, Dewey County receives approximately 28.5 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Lobelia during the growing season.

Annual Blooms in Spring Pollinator-friendly
Dewey County, OK (Zone 7a) Moderate season
194 days
Last Spring Frost April 13
194 growing days
First Fall Frost October 24

Dewey County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (76 days to spare)
Start indoors: Feb 2 Transplant: Mar 16 🌸 Bloom: May 11 – Aug 3
Recommended (50%) ✓ Fits season (75 days to spare)
Start indoors: Feb 9 Transplant: Mar 23 🌸 Bloom: May 18 – Aug 10
Safe Start (90%) ✓ Fits season (75 days to spare)
Start indoors: Feb 25 Transplant: Apr 8 🌸 Bloom: Jun 3 – Aug 26

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 Dewey County

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

Soil pH

Your soil pH (6.2–7.2) overlaps with Lobelia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Lobelia will thrive.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

3
successive plantings in your 194-day season

Sow every 8 weeks. Last sowing by Aug 05 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 794 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Lobelia

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

Month Lobelia Needs Rainfall You Supplement Action
Jan 0.7" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 4.3" 3" 1.3" 💧 Light watering
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 4.6" 0" ✅ Rainfall sufficient
Jul 4.3" 3.5" 0.8" 💧 Light watering
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 2.5" 1.8" 💧 Light watering
Oct 4.3" 1.7" 2.6" 🚿 Regular watering
Nov 0.9" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

Lobelia 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.

Lobelia needs ~1,481 GDD — county provides 3,831 GDD Excellent fit

Lobelia Planting Timeline — Dewey County, OK

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 9 Feb 9 – Feb 23
Transplant Outdoors March 23 Mar 23 – Apr 6
Bloom May 18 May 18 – Aug 10

· 6" apart · Rows 8" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

70–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

194 days in Dewey County

Growing Tips for Lobelia in Dewey County

Direct sow Lobelia outdoors after April 13 in Dewey 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 and requires light to germinate; surface-sow and press gently. Keep at 65–70°F. Not reliably direct-sown. Transplant in cool weather, 2–4 weeks before last frost date is acceptable in zones 5+. Shear plants by one-third after the first bloom flush to encourage a second flush in fall. Provide afternoon shade in zones 7+ to extend bloom into summer.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lobelia in Dewey County, OK?

Dewey County is in Zone 7a with an average last frost of April 13. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dewey County, OK?

Dewey County, Oklahoma is in USDA Hardiness Zone 7a. The average last spring frost is April 13 and first fall frost is October 24.

🌱

Your Dewey County Garden Planner — Free

A 22-page printable planner built for Dewey County (Zone 7a). 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 Dewey County, OK. 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.