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When to Plant Lemon Verbena in Cowlitz County, WA

Cowlitz County, Washington Zone 8b May

May in Cowlitz County, Washington — your action list

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

Avg. last frost April 15
Avg. first frost October 29
Soil temp (4") 72°F
Watering Moderate
Pest pressure High
Daylight 14.8 hrs
June will be here before you know it — start on
  • Starting indoors: lemon verbena

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Lemon verbena is a deciduous shrub with intensely lemon-scented leaves that retain their aroma when dried. It makes an exceptional tea and adds citrus flavor to dishes.

Cowlitz County, Washington is in USDA Zone 8b. The average last spring frost is April 15 and the first fall frost is October 29, giving you a growing season of approximately 197 days.

At an elevation of 268 feet, Cowlitz County receives approximately 47.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Lemon Verbena during the growing season.

Cowlitz County, WA (Zone 8b) Moderate season
197 days
Last Spring Frost April 15
197 growing days
First Fall Frost October 29
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Cowlitz County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (47 days to spare)
Start indoors: Feb 19 Transplant: Apr 23 🍅 Harvest: Jun 25 – Sep 3
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Feb 25 Transplant: Apr 29 🍅 Harvest: Jul 1 – Sep 9
Safe Start (90%) ✓ Fits season (54 days to spare)
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Jul 23 – 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 Cowlitz County

How your county's soil matches Lemon Verbena's growing requirements.

Soil pH

Your soil pH (5.7–6.5) overlaps with Lemon Verbena's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Lemon Verbena will thrive.

How to Plant Lemon Verbena

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Lemon Verbena

3
successive plantings in your 197-day season

Sow every 6.9 weeks. Last sowing by Jul 31 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Lemon Verbena

Lemon Verbena needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Lemon Verbena Needs Rainfall You Supplement Action
Jan 7.2" 0" ❄️ Dormant
Feb 4.6" 0" ❄️ Dormant
Mar 5.1" 0" ❄️ Dormant
Apr 4.3" 3.6" 0.7" 💧 Light watering
May 4.3" 2.9" 1.4" 💧 Light watering
Jun 4.3" 2" 2.3" 🚿 Regular watering
Jul 4.3" 0.8" 3.5" 🚿 Regular watering
Aug 4.3" 0.9" 3.4" 🚿 Regular watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 7.6" 0" ❄️ Dormant
Dec 7.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Cowlitz County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Lemon Verbena 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.

Lemon Verbena needs ~1,144 GDD — county provides 3,004 GDD Excellent fit

Lemon Verbena Planting Timeline — Cowlitz County, WA

Lemon Verbena Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 – Mar 11
Transplant Outdoors April 29 Apr 29 – May 13
Direct Sow April 22 Apr 22 – May 13
Harvest July 1 Jul 1 – Sep 9

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

197 days in Cowlitz County

Growing Tips for Lemon Verbena in Cowlitz County

Direct sow Lemon Verbena outdoors after April 15 in Cowlitz County when soil has warmed and frost danger has passed.

General growing tips

Grow in a container in cold climates and bring indoors for winter. Prune back hard in spring. Harvest leaves anytime but flavor peaks just before flowering. Dries well for tea.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Verbena in Cowlitz County, WA?

Cowlitz County is in Zone 8b with an average last frost of April 15. Plan your Lemon Verbena planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cowlitz County, WA?

Cowlitz County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 15 and first fall frost is October 29.

🌱

Your Cowlitz County Garden Planner — Free

A 24-page printable planner built for Cowlitz County (Zone 8b). 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 Cowlitz County, WA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.