When to Plant Kabocha in Bonneville County, ID
May to-do list for Bonneville County, Idaho
Welcome to May in Zone 5b. These are the moves that will have the biggest impact on your growing season.
June will be here before you know it — start on
- Transplants going out: kabocha
- Direct-sowing: kabocha
- Starting indoors: kabocha
Kabocha is a Japanese winter squash with an exceptionally sweet, dense, chestnut-like flesh and dark green skin. It is a favorite in Asian cuisine for its rich, dry texture.
Bonneville County, Idaho is in USDA Zone 5b. The average last spring frost is May 26 and the first fall frost is September 19, giving you a growing season of approximately 116 days.
At an elevation of 7,993 feet, Bonneville County receives approximately 20.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Kabocha during the growing season.
Bonneville County Soil Profile
Soil Type
Loam
Soil pH
6.5-8
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 Bonneville County
How your county's soil matches Kabocha's growing requirements.
Soil pH
Your soil pH (6.5–8.0) overlaps with Kabocha's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Bonneville County is excellent for Kabocha — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Kabocha.
How to Plant Kabocha
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Kabocha
Kabocha needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Kabocha Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 4.3" | 2.2" | 2.1" | 💧 Light watering |
| Jun | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Jul | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Aug | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | — | 1.9" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Bonneville County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Kabocha 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.
Kabocha Planting Timeline — Bonneville County, ID
Kabocha Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 21 | Apr 21 – May 5 |
| Transplant Outdoors | June 9 | Jun 9 – Jun 23 |
| Direct Sow | June 2 | Jun 2 – Jun 23 |
| Harvest | September 8 | Sep 8 – Oct 6 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | — |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
85–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
116 days in Bonneville County
Growing Tips for Kabocha in Bonneville County
Direct sow Kabocha outdoors after May 26 in Bonneville County when soil has warmed and frost danger has passed.
Common pests for Kabocha in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
Bonneville County receives only 21" of rain annually. Kabocha needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow after frost or start indoors. Harvest when the skin is hard and dull. The stem should be dry and corky. Stores well for 3-4 months in a cool, dry place.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Kabocha in Other Locations
Frequently Asked Questions
When should I plant Kabocha in Bonneville County, ID?
Bonneville County is in Zone 5b with an average last frost of May 26. Plan your Kabocha planting based on this frost date — see the calendar above for exact timing.
What planting zone is Bonneville County, ID?
Bonneville County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 26 and first fall frost is September 19.
Your Bonneville County Garden Planner — Free
A 24-page printable planner built for Bonneville County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.