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When to plant Lobelia in Elbert County, CO

In Elbert County, Lobelia is a spring-only crop. Plant May 5–May 19 once soil hits 50°F.

When to Plant Lobelia in Elbert County, CO

Elbert County, Colorado Zone 5b June

June in the garden — Elbert County, Colorado

Your garden in Elbert County, Colorado is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 12
Avg. first frost October 3
Soil temp (4") 54°F
Watering High
Pest pressure High
Daylight 14.7 hrs
  1. Collect lobelia at their peak

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Before July arrives, get these ready
  • 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.

Elbert County, Colorado is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is October 3, giving you a growing season of approximately 144 days.

At an elevation of 5,587 feet, Elbert County receives approximately 22.1 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Lobelia during the growing season.

Annual Blooms in Spring Pollinator-friendly
Elbert County, CO (Zone 5b) Short season
144 days
Last Spring Frost May 12
144 growing days
First Fall Frost October 3

Elbert County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (17 days to spare)
Start indoors: Feb 22 Transplant: Apr 26 🌸 Bloom: Jun 21 – Sep 6
Recommended (50%) ✓ Fits season (18 days to spare)
Start indoors: Mar 3 Transplant: May 5 🌸 Bloom: Jun 30 – Sep 15
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Mar 19 Transplant: May 21 🌸 Bloom: Jul 16 – Oct 1

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 Elbert County

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

Soil pH

Your soil pH (6.2–7.7) overlaps with Lobelia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Lobelia.

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Lobelia.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

2
successive plantings in your 144-day season

Sow every 8 weeks. Last sowing by Jul 15 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,008 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 4.3" 2.4" 1.9" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 1.9" 2.4" 🚿 Regular watering
Aug 4.3" 2.3" 2" 💧 Light watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 4.3" 1.9" 2.4" 🚿 Regular watering
Nov 1.8" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Elbert 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 ~1,144 GDD — county provides 2,196 GDD Excellent fit

Lobelia Planting Timeline — Elbert County, CO

Lobelia Planting Calendar

Activity When Date Range
Start Indoors March 3 Mar 3 – Mar 17
Transplant Outdoors May 5 May 5 – May 19
Bloom June 30 Jun 30 – Sep 15

· 6" apart · Rows 8" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

70–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

144 days in Elbert County

Growing Tips for Lobelia in Elbert County

Direct sow Lobelia outdoors after May 12 in Elbert County when soil has warmed and frost danger has passed.

Elbert 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 Elbert County, CO?

Elbert County is in Zone 5b with an average last frost of May 12. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Elbert County, CO?

Elbert County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is October 3.

When should I plant Lobelia in Elbert County, CO?

In Elbert County, CO, plant Lobelia after the last frost (around May 12) and before the first frost (around October 3). Best results when soil holds above 50°F.

What growing zone is Elbert County, CO for Lobelia?

Elbert County sits in USDA Zone 5b. Lobelia grows reliably in zones 3a through 9b, so it's a good fit here.

Can Lobelia grow in Elbert County's climate?

Yes — Lobelia grows well in Elbert County's temperate climate. Elbert County averages a 144-day frost-free season, with last frost around May 12 and first frost around October 3.

🌱

Your Elbert County Garden Planner — Free

A 22-page printable planner built for Elbert County (Zone 5b). 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 Elbert County, CO. 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.