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When to plant Lobelia in Mower County, MN

Plant Lobelia in Mower County, between April 28 and May 12 — the only viable window. Zone 4b's short season (162 frost-free days) rules out a fall crop.

When to Plant Lobelia in Mower County, MN

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.

Mower County, Minnesota is in USDA Zone 4b. The average last spring frost is April 28 and the first fall frost is October 7, giving you a growing season of approximately 162 days.

At an elevation of 577 feet, Mower County receives approximately 33 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Lobelia to ensure they mature before fall.

Annual Blooms in Spring Pollinator-friendly
Mower County, MN (Zone 4b) Moderate season
162 days
Last Spring Frost April 28
162 growing days
First Fall Frost October 7

Mower County Soil Profile

Soil Type

Silt Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Start indoors: Feb 13 Transplant: Apr 24 🌸 Bloom: Jun 19 – Aug 21
Recommended (50%) ✓ Fits season (43 days to spare)
Start indoors: Feb 17 Transplant: Apr 28 🌸 Bloom: Jun 23 – Aug 25
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Mar 5 Transplant: May 14 🌸 Bloom: Jul 9 – Sep 10

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 Mower County

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

Soil pH

Your soil pH (6.3–6.7) is within Lobelia's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Lobelia will thrive.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

2
successive plantings in your 162-day season

Sow every 8 weeks. Last sowing by Jul 19 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 208 gal / 100 sq ft

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 ~862 GDD — county provides 1,863 GDD Excellent fit

Lobelia Planting Timeline — Mower County, MN

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 17 Feb 17 – Mar 3
Transplant Outdoors April 28 Apr 28 – May 12
Bloom June 23 Jun 23 – Aug 25

· 6" apart · Rows 8" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–80 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

162 days in Mower County

Growing Tips for Lobelia in Mower County

Direct sow Lobelia outdoors after April 28 in Mower 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 Mower County, MN?

Mower County is in Zone 4b with an average last frost of April 28. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mower County, MN?

Mower County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is April 28 and first fall frost is October 7.

When should I plant Lobelia in Mower County, MN?

In Mower County, MN, plant Lobelia after the last frost (around April 28) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Mower County, MN for Lobelia?

Mower County sits in USDA Zone 4b. Lobelia grows reliably in zones 3a through 9b, so it's a good fit here.

Can Lobelia grow in Mower County's climate?

Yes — Lobelia grows well in Mower County's temperate climate. Mower County averages a 162-day frost-free season, with last frost around April 28 and first frost around October 7.

🌱

Your Mower County Garden Planner — Free

A 22-page printable planner built for Mower County (Zone 4b). 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 Mower County, MN. Local conditions may vary. Last updated: July 2026.

Sources & credits

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