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When to Plant Acorn Squash in Mason County, WA

Mason County, Washington Zone 8b May

Your May game plan for Mason County, Washington

Your Mason County, Washington garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost April 18
Avg. first frost October 29
Soil temp (4") 68°F
Watering High
Pest pressure High
Daylight 14.9 hrs
  1. Plant out acorn squash

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Get acorn squash seeds going inside

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

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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.

Mason County, Washington is in USDA Zone 8b. The average last spring frost is April 18 and the first fall frost is October 29, giving you a growing season of approximately 194 days.

At an elevation of 230 feet, Mason County receives approximately 36.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Acorn Squash during the growing season.

Mason County, WA (Zone 8b) Moderate season
194 days
Last Spring Frost April 18
194 growing days
First Fall Frost October 29

Mason County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (61 days to spare)
Start indoors: Mar 8 Transplant: Apr 19 🍅 Harvest: Jul 12 – Aug 16
Recommended (50%) ✓ Fits season (61 days to spare)
Start indoors: Mar 21 Transplant: May 2 🍅 Harvest: Jul 25 – Aug 29
Safe Start (90%) ✓ Fits season (74 days to spare)
Start indoors: Apr 11 Transplant: May 23 🍅 Harvest: Aug 15 – Sep 19

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 Mason County

How your county's soil matches Acorn Squash's growing requirements.

Soil pH

Your soil pH (5.4–6.7) overlaps with Acorn Squash's range (5.5–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Mason County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (5.3%) — Acorn Squash will thrive.

How to Plant Acorn Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Acorn Squash

2
successive plantings in your 194-day season

Sow every 9.1 weeks. Last sowing by Jul 21 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 535 gal / 100 sq ft

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 5" 0" ❄️ Dormant
Feb 3.7" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 4.8" 2.9" 1.9" 💧 Light watering
May 4.8" 1.8" 3" 🚿 Regular watering
Jun 4.8" 1.5" 3.3" 🚿 Regular watering
Jul 4.8" 0.6" 4.2" 🚿 Regular watering
Aug 4.8" 0.7" 4.1" 🚿 Regular watering
Sep 4.8" 1.3" 3.5" 🚿 Regular watering
Oct 4.8" 3.2" 1.6" 💧 Light watering
Nov 6.5" 0" ❄️ Dormant
Dec 5.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Mason 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 needs ~1,238 GDD — county provides 2,667 GDD Excellent fit

Acorn Squash Planting Timeline — Mason County, WA

Acorn Squash Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors May 2 May 2 – May 16
Direct Sow April 25 Apr 25 – May 16
Harvest July 25 Jul 25 – Aug 29

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Harvest
August Harvest
September
October
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: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

194 days in Mason County

Growing Tips for Acorn Squash in Mason County

Direct sow Acorn Squash outdoors after April 18 in Mason 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.

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

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Acorn Squash in Mason County, WA?

Mason County is in Zone 8b with an average last frost of April 18. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mason County, WA?

Mason County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 18 and first fall frost is October 29.

🌱

Your Mason County Garden Planner — Free

A 24-page printable planner built for Mason County (Zone 8b). 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 Mason County, WA. 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.