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When to Plant Lemongrass in Kalawao County, HI

Kalawao County, Hawaii Zone 11a May

What to do in May

Welcome to May in Zone 11a. These are the moves that will have the biggest impact on your growing season.

Soil temp (4") 83°F
Watering High
Pest pressure High
Daylight 13 hrs

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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.

Kalawao County, Hawaii is in USDA Zone 11a. The average last spring frost is January 1 and the first fall frost is December 31, giving you a growing season of approximately 364 days.

At an elevation of 402 feet, Kalawao County receives approximately 28.4 inches of rainfall annually with predominantly silty clay soil. Summer highs average 85°F, providing good warmth for Lemongrass during the growing season. Clay soil retains moisture well for Lemongrass, but amend with compost to improve drainage and prevent root rot.

Kalawao County, HI (Zone 11a) Year-round
364 days
Last Spring Frost January 1
364 growing days
First Fall Frost December 31
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Kalawao County Soil Profile

Soil Type

Silty Clay

Soil pH

5.7-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 4 Transplant: Apr 22 🍅 Harvest: Jul 8 – Oct 7
Recommended (50%) ✓ Fits season (8 days to spare)
Start indoors: Mar 4 Transplant: Apr 22 🍅 Harvest: Jul 8 – Oct 7
Safe Start (90%) ✓ Fits season (8 days to spare)
Start indoors: Mar 4 Transplant: Apr 22 🍅 Harvest: Jul 8 – Oct 7

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 Kalawao County

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

Soil pH

Your soil pH (5.7–6.7) is within Lemongrass's preferred range (5.5–7.5).

Soil Texture

Your silty clay soil in Kalawao County is workable for Lemongrass. Add compost annually to improve structure.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Lemongrass.

How to Plant Lemongrass

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

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.3″/week
You supply
1.4″/week
Watering frequency 2-3 times/week
Season total 4,573 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 6.5" 4.1" 2.4" 💧 Light watering
Feb 6.5" 3.1" 3.4" 🚿 Regular watering
Mar 6.5" 3.4" 3.1" 💧 Light watering
Apr 6.5" 2.6" 3.9" 🚿 Regular watering
May 6.5" 1.6" 4.9" 🚿 Regular watering
Jun 6.5" 0.9" 5.6" 🚿 Regular watering
Jul 6.5" 0.7" 5.8" 🚿 Regular watering
Aug 6.5" 0.9" 5.6" 🚿 Regular watering
Sep 6.5" 1.4" 5.1" 🚿 Regular watering
Oct 6.5" 2.8" 3.7" 🚿 Regular watering
Nov 6.5" 2.9" 3.6" 🚿 Regular watering
Dec 6.5" 4" 2.5" 💧 Light watering

Water needs are for active growing months only (Jan–Dec in Kalawao 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 ~1,341 GDD — county provides 5,018 GDD Excellent fit

Lemongrass Planting Timeline — Kalawao County, HI

Lemongrass Planting Calendar

Activity When Date Range
Start Indoors November 20 Nov 20 – Dec 4
Transplant Outdoors January 8 Jan 8 – Jan 22
Direct Sow January 8 Jan 8 – Jan 29
Harvest March 26 Mar 26 – Jun 25

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

75–120 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 11a

📆 Growing Season

364 days in Kalawao County

Growing Tips for Lemongrass in Kalawao County

With Kalawao County's clay soil (37% clay), work in 3-4 inches of compost before planting Lemongrass. Avoid tilling when soil is wet to prevent compaction.

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 Kalawao County, HI?

Kalawao County is in Zone 11a with an average last frost of January 1. Plan your Lemongrass planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kalawao County, HI?

Kalawao County, Hawaii is in USDA Hardiness Zone 11a. The average last spring frost is January 1 and first fall frost is December 31.

🌱

Your Kalawao County Garden Planner — Free

A 24-page printable planner built for Kalawao County (Zone 11a). 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 Kalawao County, HI. 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.