When to Plant Napa Cabbage in Kalawao County, HI
May to-do list for Kalawao County, Hawaii
Your Kalawao County, Hawaii garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.
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 Napa Cabbage during the growing season. Clay soil retains moisture well for Napa Cabbage, but amend with compost to improve drainage and prevent root rot.
Kalawao County Soil Profile
Soil Type
Silty Clay
Soil pH
5.7-6.7
Drainage
Well Drained
Plant Planting Risk Windows
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 Napa Cabbage's growing requirements.
Soil pH
Your soil pH (5.7–6.7) overlaps with Napa Cabbage's range (6.0–7.5), though not a perfect match.
Soil Texture
Your silty clay soil in Kalawao County is workable for Napa Cabbage. Add compost annually to improve structure.
Organic Matter
Organic matter is moderate (3.9%). Annual compost additions will help Napa Cabbage.
How to Plant Napa Cabbage
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Napa Cabbage
Napa Cabbage 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 | Napa Cabbage 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.
Napa Cabbage 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.
Napa Cabbage Planting Timeline — Kalawao County, HI
Napa Cabbage 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 26 | Feb 26 – Apr 2 |
| Fall Sowing | November 5 | Nov 5 – Nov 19 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | Harvest |
| March | Harvest |
| April | Harvest |
| May | — |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | Fall Sowing |
| December | Start Indoors Direct Sow |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
55–75 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 11a
📆 Growing Season
364 days in Kalawao County
Growing Tips for Napa Cabbage in Kalawao County
With Kalawao County's clay soil (37% clay), work in 3-4 inches of compost before planting Napa Cabbage. Avoid tilling when soil is wet to prevent compaction.
Common pests for Napa Cabbage in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.
Companion Planting
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Napa Cabbage in Other Locations
Frequently Asked Questions
When should I plant Napa Cabbage in Kalawao County, HI?
Kalawao County is in Zone 11a with an average last frost of January 1. Plan your Napa Cabbage 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.