When to Plant Acorn Squash in Stillwater County, MT
May in the garden — Stillwater County, Montana
We've pulled the most time-sensitive tasks for Stillwater County, Montana this May and put them front and centre. Tackle them in order.
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Plant acorn squash from seed, right in the garden
These tolerate cool soil, so you're not gambling by sowing now.
To set up a strong June, finish these tasks
- Transplants going out: acorn squash
- Starting indoors: acorn squash
Acorn squash is a small winter squash with dark green, ribbed skin and mildly sweet orange flesh. It is perfect for stuffing and roasting as individual servings.
Stillwater County, Montana is in USDA Zone 5a. The average last spring frost is May 22 and the first fall frost is September 22, giving you a growing season of approximately 123 days.
At an elevation of 6,319 feet, Stillwater County receives approximately 16.6 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Acorn Squash to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Acorn Squash successfully. Mulch heavily to conserve soil moisture.
Stillwater County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.8
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 Stillwater County
How your county's soil matches Acorn Squash's growing requirements.
Soil pH
Your soil pH (6.3–7.8) is more alkaline than Acorn Squash prefers (5.5–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Stillwater County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.7%). Annual compost additions will help Acorn Squash.
How to Plant Acorn Squash
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Acorn Squash
Acorn Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.
| Month | Acorn Squash Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.1" | 0" | ❄️ Dormant |
| Feb | — | 1.1" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | — | 1.8" | 0" | ❄️ Dormant |
| May | 4.8" | 2" | 2.8" | 🚿 Regular watering |
| Jun | 4.8" | 1.1" | 3.7" | 🚿 Regular watering |
| Jul | 4.8" | 1.4" | 3.4" | 🚿 Regular watering |
| Aug | 4.8" | 1.7" | 3.1" | 🚿 Regular watering |
| Sep | 4.8" | 1.4" | 3.4" | 🚿 Regular watering |
| Oct | — | 1.4" | 0" | ❄️ Dormant |
| Nov | — | 1.1" | 0" | ❄️ Dormant |
| Dec | — | 1.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Stillwater County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Acorn Squash 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.
Acorn Squash Planting Timeline — Stillwater County, MT
Acorn Squash Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 17 | Apr 17 – May 1 |
| Transplant Outdoors | June 5 | Jun 5 – Jun 19 |
| Direct Sow | May 29 | May 29 – Jun 19 |
| Harvest | August 28 | Aug 28 – Oct 2 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.1"/week · 1-2 times/week
📅 Days to Maturity
80–100 days
🧪 Soil pH
Needs 5.5–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
123 days in Stillwater County
Growing Tips for Acorn Squash in Stillwater County
Direct sow Acorn Squash outdoors after May 22 in Stillwater County when soil has warmed and frost danger has passed.
Common pests for Acorn Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.
Stillwater County receives only 17" of rain annually. Acorn Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow after last frost. Harvest when the ground spot turns orange and the skin is hard. Acorn squash has a shorter storage life than butternut, lasting about 2 months.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Acorn Squash in Other Locations
Frequently Asked Questions
When should I plant Acorn Squash in Stillwater County, MT?
Stillwater County is in Zone 5a with an average last frost of May 22. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.
What planting zone is Stillwater County, MT?
Stillwater County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 22 and first fall frost is September 22.
Your Stillwater County Garden Planner — Free
A 24-page printable planner built for Stillwater County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.