Lobelia Planting Guide

June

Planting lobelia in June

Everything below applies to lobelia broadly. For a plan that's dialled into your county's frost dates and soil, tap your location.

Sun partial shade

Water moderate

Days to harvest 70–80

Spacing 6″

How to water lobelia
About an inch of water a week keeps lobelia happy. Check your weather forecast before watering — skip if rain is coming.
Where to put lobelia
lobelia wants at least 6 hours of direct sun. Less than that and you'll get leggy plants with weak yields.
Check your local forecast before planting
Your zone determines the exact week to plant lobelia. Pick your county below and we'll line everything up against your frost dates.

Show me lobelia timing for my zone →

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.

Lobelia erinus · Flower · Campanulaceae family · 70–80 days to maturity

Annual Blooms in Spring Pollinator-friendly

Why it matters: If you're just starting a flower garden in your area, Lobelia is a forgiving first pick. It tolerates imperfect soil, mild drought, and the occasional missed watering. The reward: weeks (sometimes months) of continuous color.

Get Your Personalized Lobelia Planting Dates

Enter your ZIP code to see exact planting dates, soil compatibility, and growing tips specific to your county.

Where Can You Grow Lobelia?

Zone Compatibility for Lobelia Zones 3a – 9b

1a 1b 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b 11a 11b 12a 12b 13a 13b

Ideal (data available) Suitable Marginal Not recommended

Planting Dates by Zone

Zone	Start Indoors	Direct Sow	Transplant	Bloom
Zone 3a	Mar 6	—	May 22	Jul 17 – Aug 28
Zone 3b	Mar 1	—	May 17	Jul 12 – Aug 30
Zone 4a	Feb 25	—	May 6	Jul 1 – Aug 26
Zone 4b	Feb 20	—	May 1	Jun 26 – Aug 28
Zone 5a	Feb 14	—	Apr 18	Jun 13 – Aug 22
Zone 5b	Feb 7	—	Apr 11	Jun 6 – Aug 22
Zone 6a	Feb 6	—	Mar 27	May 22 – Aug 14
Zone 6b	Jan 30	—	Mar 20	May 15 – Aug 7
Zone 7a	Jan 21	—	Mar 4	Apr 29 – Jul 22
Zone 7b	Jan 14	—	Feb 18	Apr 15 – Jun 24
Zone 8a	Jan 11	—	Feb 1	Mar 29 – May 24
Zone 8b	Dec 31	—	Jan 14	Mar 11 – Apr 22
Zone 9a	Dec 16	—	Dec 16	Feb 10 – Mar 10
Zone 9b	Nov 30	—	Nov 23	Jan 18 – Feb 15

Why are some columns showing "—"?

Direct Sow shows "—" because Lobelia benefits from being started indoors first, then transplanted after the last frost.

How to Plant Lobelia

Between Plants

Between Rows

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

Water when the top inch of soil feels dry. Consistent moisture produces the best results.

🧪 Soil pH

6 – 7

Prefers neutral to slightly acidic soil — ideal for most garden beds.

🗺️ Hardiness Zones

Zone 3a – 9b

📅 Days to Maturity

70–80 days

Medium-season crop. Start early for best results in shorter seasons.

👪 Plant Family

Campanulaceae

Rotate with other families yearly to prevent soil-borne diseases. Don't plant in the same spot where Campanulaceae family crops grew last year.

Succession Planting Lobelia

Lobelia matures in just 70–80 days, making it ideal for succession planting. In a typical 180-day growing season, you can get up to 2 successive plantings by sowing every 8 weeks.

Your actual succession count depends on your local frost dates. Enter your ZIP code to get personalized succession planting dates for your area.

Companion Planting for Lobelia

✅ Good Companions

Petunias Sweet Alyssum Begonias Impatiens

Check more combinations with our Companion Planting Checker →

Growing Tips for Lobelia

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.

Saving Lobelia Seeds

Recommended for Your Garden

🌱

Seed Starting Trays $8-20

Start seeds indoors with reusable cell trays and humidity domes.

🧪

Soil Test Kit $12-25

Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.

🏷️

Garden Plant Markers $6-12

Keep your garden organized with durable, weather-resistant plant labels.

Reader favourite

Seed Saving & Storage Guide

$27 $157 value

Most saved seeds go bad before next season. This shows exactly when to pick, how to dry, and where to store seeds from 200 plants so yours don't.

200 plants, step-by-step: life cycle, pollination type, isolation
Exact temperature + humidity ranges that keep seeds viable
Bonus: searchable Google Sheets tracker + custom GPT assistant

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Lobelia by State

Frequently Asked Questions

How long does it take to grow Lobelia?

Lobelia (Lobelia erinus) takes 70 to 80 days from planting to harvest. Exact timing depends on your variety, growing conditions, and USDA zone.

What zones can Lobelia grow in?

Lobelia can be grown in USDA zones 3a through 9b. Use the planting calendar above to find the exact dates for your zone.

How much sun does Lobelia need?

Growing Lobelia requires Partial Shade (3-6 hours), Moderate — regular watering, and soil pH of 6 to 7.