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When to Plant Kai Lan in Kalawao County, HI

Kalawao County, Hawaii Zone 11a May

May to-do list for Kalawao County, Hawaii

Here's what deserves your attention in Kalawao County, Hawaii this month. Everything below is tailored to Zone 11a and timed around your local frost dates.

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

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Kai lan (Chinese broccoli) is a brassica grown for its thick, glossy stems and small flower buds. It has a slightly bitter, broccoli-like flavor essential in Cantonese cooking.

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 Kai Lan during the growing season. Clay soil retains moisture well for Kai Lan, 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 (106 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Jun 3 – Jul 1
Recommended (50%) ✓ Fits season (106 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Jun 3 – Jul 1
Safe Start (90%) ✓ Fits season (106 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Jun 3 – Jul 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 Kalawao County

How your county's soil matches Kai Lan's growing requirements.

Soil pH

Your soil pH (5.7–6.7) overlaps with Kai Lan's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Kai Lan

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Plant 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 2,624 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Kai Lan

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

Month Kai Lan Needs Rainfall You Supplement Action
Jan 4.3" 4.1" 0.2" 💧 Light watering
Feb 4.3" 3.1" 1.2" 💧 Light watering
Mar 4.3" 3.4" 0.9" 💧 Light watering
Apr 4.3" 2.6" 1.7" 💧 Light watering
May 4.3" 1.6" 2.7" 🚿 Regular watering
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 0.7" 3.6" 🚿 Regular watering
Aug 4.3" 0.9" 3.4" 🚿 Regular watering
Sep 4.3" 1.4" 2.9" 🚿 Regular watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 4.3" 2.9" 1.4" 💧 Light watering
Dec 4.3" 4" 0.3" 💧 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.

Kai Lan 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.

Kai Lan needs ~722 GDD — county provides 5,018 GDD Excellent fit

Kai Lan Planting Timeline — Kalawao County, HI

Kai Lan Planting Calendar

Activity When Date Range
Start Indoors December 4 Dec 4 – Dec 18
Transplant Outdoors January 1 Jan 1 – Jan 15
Direct Sow December 11 Dec 11 – Jan 1
Harvest February 19 Feb 19 – Mar 19
Fall Sowing November 5 Nov 5 – Nov 19

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 11a

📆 Growing Season

364 days in Kalawao County

Growing Tips for Kai Lan in Kalawao County

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

Your generous 365.0-day season in Kalawao County allows multiple plantings of Kai Lan. Sow every 22.0 days for continuous harvest.

Common pests for Kai Lan in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or fall. Harvest when flower buds first appear but before they open. Cut stems at the base to encourage side shoots. Prefers cool weather.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kai Lan in Kalawao County, HI?

Kalawao County is in Zone 11a with an average last frost of January 1. Plan your Kai Lan 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.