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When to Plant Microgreens in Kalawao County, HI

Kalawao County, Hawaii Zone 11a May

This month in Kalawao County, Hawaii

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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Microgreens are young seedlings of vegetables and herbs harvested at the cotyledon or first true leaf stage. They pack concentrated flavors and nutrients in a tiny package.

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 Microgreens during the growing season. Clay soil retains moisture well for Microgreens, 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 (148 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Apr 22 – May 20
Recommended (50%) ✓ Fits season (148 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Apr 22 – May 20
Safe Start (90%) ✓ Fits season (148 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Apr 22 – May 20

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 Microgreens's growing requirements.

Soil pH

Your soil pH (5.7–6.7) overlaps with Microgreens's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Microgreens

0.5"
Planting Depth
2"
Between Plants
6"
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 Microgreens

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

Month Microgreens 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.

Microgreens 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.

Microgreens needs ~192 GDD — county provides 5,018 GDD Excellent fit

Microgreens Planting Timeline — Kalawao County, HI

Microgreens 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 January 8 Jan 8 – Feb 5
Fall Sowing November 5 Nov 5 – Nov 19

Plant 0.5" deep · 2" apart · Rows 6" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

7–21 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 11a

📆 Growing Season

364 days in Kalawao County

Growing Tips for Microgreens in Kalawao County

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

Your generous 365.0-day season in Kalawao County allows multiple plantings of Microgreens. Sow every 3.0 days for continuous harvest.

General growing tips

Sow seeds densely on shallow trays of moist growing medium. Cover until germination, then provide light. Harvest with scissors when 1-3 inches tall. Grow year-round indoors.

Frequently Asked Questions

When should I plant Microgreens in Kalawao County, HI?

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