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When to plant Lobelia in Thomas County County,

In Thomas County County, Lobelia is a single-season spring crop — there's no second fall window. Plant April 16–April 30 for an 80-day harvest, finishing well before the October 12 first frost.

When to Plant Lobelia in Thomas County, KS

Thomas County, Kansas Zone 6a June

Your June gardening checklist

Welcome to June in Zone 6a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 30
Avg. first frost October 12
Soil temp (4") 71°F
Watering High
Pest pressure High
Daylight 14.8 hrs
  1. Pick lobelia

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

July prep starts now
  • Starting indoors: lobelia
  • 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.

Thomas County, Kansas is in USDA Zone 6a. The average last spring frost is April 30 and the first fall frost is October 12, giving you a growing season of approximately 165 days.

At an elevation of 810 feet, Thomas County receives approximately 26.4 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Lobelia during the growing season.

Annual Blooms in Spring Pollinator-friendly
Thomas County, KS (Zone 6a) Moderate season
165 days
Last Spring Frost April 30
165 growing days
First Fall Frost October 12

Thomas County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.5

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (38 days to spare)
Start indoors: Feb 21 Transplant: Apr 11 🌸 Bloom: Jun 6 – Aug 29
Recommended (50%) ✓ Fits season (39 days to spare)
Start indoors: Feb 26 Transplant: Apr 16 🌸 Bloom: Jun 11 – Sep 3
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Mar 12 Transplant: Apr 30 🌸 Bloom: Jun 25 – Sep 17

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 Thomas County

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

Soil pH

Your soil pH (6.8–7.5) is more alkaline than Lobelia prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Lobelia will thrive.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

2
successive plantings in your 165-day season

Sow every 8 weeks. Last sowing by Jul 24 to harvest before frost.

Lobelia 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 578 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 2.1" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.2" 1.1" 💧 Light watering
Jun 4.3" 2" 2.3" 🚿 Regular watering
Jul 4.3" 2.3" 2" 💧 Light watering
Aug 4.3" 2.6" 1.7" 💧 Light watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 1.7" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Thomas 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 ~1,200 GDD — county provides 2,640 GDD Excellent fit

Lobelia Planting Timeline — Thomas County, KS

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 26 Feb 26 – Mar 12
Transplant Outdoors April 16 Apr 16 – Apr 30
Bloom June 11 Jun 11 – Sep 3

· 6" apart · Rows 8" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors
May
June Bloom
July Bloom
August Bloom
September Bloom
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: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

165 days in Thomas County

Growing Tips for Lobelia in Thomas County

Direct sow Lobelia outdoors after April 30 in Thomas 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 Thomas County, KS?

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

What planting zone is Thomas County, KS?

Thomas County, Kansas is in USDA Hardiness Zone 6a. The average last spring frost is April 30 and first fall frost is October 12.

When should I plant Lobelia in Thomas County County, ?

In Thomas County County, , plant Lobelia after the last frost (around April 30) and before the first frost (around October 12). Best results when soil holds above 50°F.

What growing zone is Thomas County County, for Lobelia?

Thomas County County sits in USDA Zone 6a. Lobelia grows reliably in zones 3a through 9b, so it's a good fit here.

Can Lobelia grow in Thomas County County's climate?

Yes — Lobelia grows well in Thomas County County's temperate climate. Thomas County County averages a 165-day frost-free season, with last frost around April 30 and first frost around October 12.

🌱

Your Thomas County Garden Planner — Free

A 22-page printable planner built for Thomas 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.

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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 Thomas County, KS. Local conditions may vary. Last updated: June 2026.

Sources & credits

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