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When to Plant Lemongrass in Cowlitz County, WA

Cowlitz County, Washington Zone 8b May

Your May game plan for Cowlitz County, Washington

May is a pivotal month for Cowlitz County, Washington gardens. Focus on these tasks first and you'll set up the rest of the season for success.

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 prep starts now
  • Starting indoors: lemongrass

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Lemongrass is a tropical grass with a strong citrus aroma used extensively in Southeast Asian cuisine. The swollen stem bases are the most flavorful part.

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 Lemongrass 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

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 (12 days to spare)
Start indoors: Feb 19 Transplant: Apr 23 🍅 Harvest: Jul 9 – Oct 8
Recommended (50%) ✓ Fits season (15 days to spare)
Start indoors: Feb 25 Transplant: Apr 29 🍅 Harvest: Jul 15 – Oct 14
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Aug 6 – Nov 5

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 Lemongrass's growing requirements.

Soil pH

Your soil pH (5.7–6.5) is within Lemongrass's preferred range (5.5–7.5).

Soil Texture

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

Organic Matter

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

How to Plant Lemongrass

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

Succession Planting Lemongrass

3
successive plantings in your 197-day season

Sow every 8.6 weeks. Last sowing by Jul 01 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 858 gal / 100 sq ft

Monthly Watering Guide for Lemongrass

Lemongrass needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Lemongrass Needs Rainfall You Supplement Action
Jan 7.2" 0" ❄️ Dormant
Feb 4.6" 0" ❄️ Dormant
Mar 5.1" 0" ❄️ Dormant
Apr 6.5" 3.6" 2.9" 💧 Light watering
May 6.5" 2.9" 3.6" 🚿 Regular watering
Jun 6.5" 2" 4.5" 🚿 Regular watering
Jul 6.5" 0.8" 5.7" 🚿 Regular watering
Aug 6.5" 0.9" 5.6" 🚿 Regular watering
Sep 6.5" 1.6" 4.9" 🚿 Regular watering
Oct 6.5" 3.4" 3.1" 💧 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.

Lemongrass 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.

Lemongrass needs ~1,487 GDD — county provides 3,004 GDD Excellent fit

Lemongrass Planting Timeline — Cowlitz County, WA

Lemongrass 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 15 Jul 15 – Oct 14

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 Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

75–120 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 8b

📆 Growing Season

197 days in Cowlitz County

Growing Tips for Lemongrass in Cowlitz County

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

Common pests for Lemongrass in this region include corn earworm and corn borers. Use row covers early in the season and inspect plants weekly.

General growing tips

Start from divisions or store-bought stalks rooted in water. Grow in rich, moist soil with full sun. In cold climates, grow in containers and overwinter indoors.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemongrass in Cowlitz County, WA?

Cowlitz County is in Zone 8b with an average last frost of April 15. Plan your Lemongrass 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.