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When to Plant Lobelia in Carson County, TX

Carson County, Texas Zone 7a July

July to-do list for Carson County, Texas

July rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Carson County, Texas.

Avg. last frost April 14
Avg. first frost October 25
Soil temp (4") 80°F
Watering Low
Pest pressure High
Daylight 14.2 hrs
  1. Collect lobelia at their peak

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

A few tasks this July that'll pay off in August
  • 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.

Carson County, Texas is in USDA Zone 7a. The average last spring frost is April 14 and the first fall frost is October 25, giving you a growing season of approximately 194 days.

At an elevation of 2,585 feet, Carson County receives approximately 45.2 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 99°F, so Lobelia may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Lobelia will need more frequent watering and organic matter to retain nutrients.

Annual Blooms in Spring Pollinator-friendly
Carson County, TX (Zone 7a) Moderate season
194 days
Last Spring Frost April 14
194 growing days
First Fall Frost October 25

Carson County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.9-8.8

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (74 days to spare)
Start indoors: Feb 4 Transplant: Mar 18 🌸 Bloom: May 13 – Aug 5
Recommended (50%) ✓ Fits season (75 days to spare)
Start indoors: Feb 10 Transplant: Mar 24 🌸 Bloom: May 19 – Aug 11
Safe Start (90%) ✓ Fits season (71 days to spare)
Start indoors: Feb 27 Transplant: Apr 10 🌸 Bloom: Jun 5 – Aug 28

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 Carson County

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

Soil pH

Your soil pH (7.9–8.8) is more alkaline than Lobelia prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Carson County warms quickly in spring but drains fast. Lobelia will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Lobelia.

Organic Matter

Organic matter is low (1.0%). Add 2-3 inches of compost before planting Lobelia.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

3
successive plantings in your 194-day season

Sow every 8 weeks. Last sowing by Aug 06 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 666 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 3.5" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 1.3" 3" 🚿 Regular watering
May 4.3" 1.1" 3.2" 🚿 Regular watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 7.6" 0" ✅ Rainfall sufficient
Aug 4.3" 9" 0" ✅ Rainfall sufficient
Sep 4.3" 6.6" 0" ✅ Rainfall sufficient
Oct 4.3" 4.1" 0.2" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Carson 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 ~1,819 GDD — county provides 4,704 GDD Excellent fit

Lobelia Planting Timeline — Carson County, TX

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 10 Feb 10 – Feb 24
Transplant Outdoors March 24 Mar 24 – Apr 7
Bloom May 19 May 19 – Aug 11

· 6" apart · Rows 8" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Transplant Outdoors
April Transplant Outdoors
May Bloom
June Bloom
July Bloom
August Bloom
September
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 7a

📆 Growing Season

194 days in Carson County

Growing Tips for Lobelia in Carson County

Direct sow Lobelia outdoors after April 14 in Carson County when soil has warmed and frost danger has passed.

Sandy soil in Carson County dries quickly — mulch Lobelia with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 99°F in Carson County, provide afternoon shade for Lobelia and water deeply in the morning.

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 Carson County, TX?

Carson County is in Zone 7a with an average last frost of April 14. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carson County, TX?

Carson County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 14 and first fall frost is October 25.

🌱

Your Carson County Garden Planner — Free

A 22-page printable planner built for Carson County (Zone 7a). 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 Carson County, TX. 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.