When to Plant Turmeric in Hawaii County, HI
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Turmeric is a tropical plant producing bright orange rhizomes with a warm, earthy flavor and potent anti-inflammatory properties. It is closely related to ginger.
Hawaii County, Hawaii is in USDA Zone 12b. 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 525 feet, Hawaii County receives approximately 96.2 inches of rainfall annually with predominantly silty clay soil. Summer highs average 87°F, providing good warmth for Turmeric during the growing season. Clay soil retains moisture well for Turmeric, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Turmeric root diseases.
Hawaii County Soil Profile
Soil Type
Silty Clay
Soil pH
5.6-6.6
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 Hawaii County
How your county's soil matches Turmeric's growing requirements.
Soil pH
Your soil pH (5.6–6.6) is within Turmeric's preferred range (5.5–7.5).
Soil Texture
Your silty clay soil in Hawaii County is workable for Turmeric. Add compost annually to improve structure.
Organic Matter
Organic matter is excellent (4.1%) — Turmeric will thrive.
How to Plant Turmeric
Plant Water Budget
Monthly Watering Guide for Turmeric
Turmeric 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 | Turmeric Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | 6.5" | 13.1" | 0" | ✅ Rainfall sufficient |
| Feb | 6.5" | 11.1" | 0" | ✅ Rainfall sufficient |
| Mar | 6.5" | 11.1" | 0" | ✅ Rainfall sufficient |
| Apr | 6.5" | 8.4" | 0" | ✅ Rainfall sufficient |
| May | 6.5" | 5.6" | 0.9" | 💧 Light watering |
| Jun | 6.5" | 2.5" | 4" | 🚿 Regular watering |
| Jul | 6.5" | 2.3" | 4.2" | 🚿 Regular watering |
| Aug | 6.5" | 2.7" | 3.8" | 🚿 Regular watering |
| Sep | 6.5" | 4.7" | 1.8" | 💧 Light watering |
| Oct | 6.5" | 10.3" | 0" | ✅ Rainfall sufficient |
| Nov | 6.5" | 12.3" | 0" | ✅ Rainfall sufficient |
| Dec | 6.5" | 12" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Jan–Dec in Hawaii County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Turmeric 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.
Turmeric Planting Timeline — Hawaii County, HI
Turmeric 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 1 | Jan 1 – Jan 22 |
| Harvest | September 10 | Sep 10 – Nov 19 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | — |
| August | — |
| September | Harvest |
| October | Harvest |
| November | Start Indoors Harvest |
| December | Start Indoors |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
240–300 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 12b
📆 Growing Season
364 days in Hawaii County
Growing Tips for Turmeric in Hawaii County
With Hawaii County's clay soil (39% clay), work in 3-4 inches of compost before planting Turmeric. Avoid tilling when soil is wet to prevent compaction.
General growing tips
Plant rhizome pieces 2 inches deep in rich, moist soil after last frost. Maintain warmth and humidity. Harvest after foliage dies back in fall. In cold climates, grow in large containers.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Turmeric in Other Locations
Frequently Asked Questions
When should I plant Turmeric in Hawaii County, HI?
Hawaii County is in Zone 12b with an average last frost of January 1. Plan your Turmeric planting based on this frost date — see the calendar above for exact timing.
What planting zone is Hawaii County, HI?
Hawaii County, Hawaii is in USDA Hardiness Zone 12b. The average last spring frost is January 1 and first fall frost is December 31.
Your Hawaii County Garden Planner — Free
A 24-page printable planner built for Hawaii County (Zone 12b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.