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When to Plant Lobelia in Chelan County, WA

Chelan County, Washington Zone 7a July

Chelan County, Washington gardeners: here's your July plan

We've pulled the most time-sensitive tasks for Chelan County, Washington this July and put them front and centre. Tackle them in order.

Avg. last frost April 24
Avg. first frost October 20
Soil temp (4") 72°F
Watering Critical
Pest pressure High
Daylight 15.4 hrs
  1. Harvest lobelia as they ripen

    If you can't use it all right away, check the food-preservation section of your planner.

Coming up in August — start thinking about
  • 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.

Chelan County, Washington is in USDA Zone 7a. The average last spring frost is April 24 and the first fall frost is October 20, giving you a growing season of approximately 179 days.

At an elevation of 3,517 feet, Chelan County receives approximately 14.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Lobelia during the growing season. With low rainfall, drip irrigation is essential for growing Lobelia successfully. Mulch heavily to conserve soil moisture.

Annual Blooms in Spring Pollinator-friendly
Chelan County, WA (Zone 7a) Moderate season
179 days
Last Spring Frost April 24
179 growing days
First Fall Frost October 20

Chelan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Lobelia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (61 days to spare)
Start indoors: Feb 9 Transplant: Mar 23 🌸 Bloom: May 18 – Aug 10
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Feb 20 Transplant: Apr 3 🌸 Bloom: May 29 – Aug 21
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Mar 17 Transplant: Apr 28 🌸 Bloom: Jun 23 – Sep 15

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 Chelan County

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

Soil pH

Your soil pH (5.5–6.3) is more acidic than Lobelia prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Lobelia will thrive.

How to Plant Lobelia

6"
Between Plants
8"
Between Rows

Succession Planting Lobelia

2
successive plantings in your 179-day season

Sow every 8 weeks. Last sowing by Aug 01 to harvest before frost.

Lobelia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.3″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,275 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 2.1" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 4.3" 1.2" 3.1" 🚿 Regular watering
May 4.3" 0.9" 3.4" 🚿 Regular watering
Jun 4.3" 0.6" 3.7" 🚿 Regular watering
Jul 4.3" 0.2" 4.1" 🚿 Regular watering
Aug 4.3" 0.3" 4" 🚿 Regular watering
Sep 4.3" 0.5" 3.8" 🚿 Regular watering
Oct 4.3" 1.2" 3.1" 🚿 Regular watering
Nov 1.9" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Chelan 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 2,729 GDD Excellent fit

Lobelia Planting Timeline — Chelan County, WA

Lobelia Planting Calendar

Activity When Date Range
Start Indoors February 20 Feb 20 – Mar 6
Transplant Outdoors April 3 Apr 3 – Apr 17
Bloom May 29 May 29 – Aug 21

· 6" apart · Rows 8" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
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 · 2-3 times/week

📅 Days to Maturity

70–80 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

179 days in Chelan County

Growing Tips for Lobelia in Chelan County

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

Chelan County receives only 14" 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 Chelan County, WA?

Chelan County is in Zone 7a 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 Chelan County, WA?

Chelan County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is April 24 and first fall frost is October 20.

🌱

Your Chelan County Garden Planner — Free

A 22-page printable planner built for Chelan 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 Chelan County, WA. 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.