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When to plant Lobelia in Rush County County,

Rush County County sits in cold Zone 6b. Plant Lobelia April 10–April 24 for the single annual harvest; the October 15 first frost closes the window.

When to Plant Lobelia in Rush County, KS

Rush County, Kansas Zone 6b June

Your June planting checklist for Rush County, Kansas

We've pulled the most time-sensitive tasks for Rush County, Kansas this June and put them front and centre. Tackle them in order.

Avg. last frost April 24
Avg. first frost October 15
Soil temp (4") 74°F
Watering Moderate
Pest pressure High
Daylight 14.7 hrs
  1. Start lobelia under lights

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. Pick lobelia

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

To set up a strong July, finish these tasks
  • 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.

Rush County, Kansas is in USDA Zone 6b. The average last spring frost is April 24 and the first fall frost is October 15, giving you a growing season of approximately 174 days.

At an elevation of 759 feet, Rush County receives approximately 21.7 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Lobelia during the growing season.

Annual Blooms in Spring Pollinator-friendly
Rush County, KS (Zone 6b) Moderate season
174 days
Last Spring Frost April 24
174 growing days
First Fall Frost October 15
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Rush County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.3

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Feb 13 Transplant: Apr 3 🌸 Bloom: May 29 – Aug 21
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Feb 20 Transplant: Apr 10 🌸 Bloom: Jun 5 – Aug 28
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Mar 9 Transplant: Apr 27 🌸 Bloom: Jun 22 – Sep 14

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 Rush County

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

Soil pH

Your soil pH (6.4–7.3) overlaps with Lobelia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Lobelia.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

2
successive plantings in your 174-day season

Sow every 8 weeks. Last sowing by Jul 27 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 885 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 0.5" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 4.3" 2.1" 2.2" 🚿 Regular watering
May 4.3" 3.4" 0.9" 💧 Light watering
Jun 4.3" 3.4" 0.9" 💧 Light watering
Jul 4.3" 2.9" 1.4" 💧 Light watering
Aug 4.3" 2.6" 1.7" 💧 Light watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 4.3" 1.5" 2.8" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Rush 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 ~1,088 GDD — county provides 2,523 GDD Excellent fit

Lobelia Planting Timeline — Rush County, KS

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 20 Feb 20 – Mar 6
Transplant Outdoors April 10 Apr 10 – Apr 24
Bloom June 5 Jun 5 – Aug 28

· 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
October
November
December
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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 6b

📆 Growing Season

174 days in Rush County

Growing Tips for Lobelia in Rush County

Direct sow Lobelia outdoors after April 24 in Rush County when soil has warmed and frost danger has passed.

Rush County receives only 22" of rain annually. Lobelia needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Rush County, KS?

Rush County is in Zone 6b with an average last frost of April 24. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rush County, KS?

Rush County, Kansas is in USDA Hardiness Zone 6b. The average last spring frost is April 24 and first fall frost is October 15.

When should I plant Lobelia in Rush County County, ?

In Rush County County, , plant Lobelia after the last frost (around April 24) and before the first frost (around October 15). Best results when soil holds above 50°F.

What growing zone is Rush County County, for Lobelia?

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

Can Lobelia grow in Rush County County's climate?

Yes — Lobelia grows well in Rush County County's temperate climate. Rush County County averages a 174-day frost-free season, with last frost around April 24 and first frost around October 15.

🌱

Your Rush County Garden Planner — Free

A 22-page printable planner built for Rush County (Zone 6b). 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 Rush County, KS. 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.