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When to Plant Acorn Squash in Humboldt County, CA

Humboldt County, California Zone 9b May

May to-do list for Humboldt County, California

Your garden in Humboldt County, California is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost February 27
Avg. first frost November 28
Soil temp (4") 74°F
Watering Critical
Pest pressure High
Daylight 14.3 hrs
  1. Basket week: acorn squash

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Before June arrives, get these ready
  • First harvests: acorn squash

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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.

Humboldt County, California is in USDA Zone 9b. The average last spring frost is February 27 and the first fall frost is November 28, giving you a growing season of approximately 274 days.

At an elevation of 148 feet, Humboldt County receives approximately 22.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Acorn Squash during the growing season. Sandy soil warms quickly in spring — great for early planting — but Acorn Squash will need more frequent watering and organic matter to retain nutrients.

Humboldt County, CA (Zone 9b) Year-round
274 days
Last Spring Frost February 27
274 growing days
First Fall Frost November 28

Humboldt County Soil Profile

Soil Type

Sandy Loam

Soil pH

6.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (157 days to spare)
Start indoors: Jan 16 Transplant: Feb 20 🍅 Harvest: May 15 – Jun 19
Recommended (50%) ✓ Fits season (148 days to spare)
Start indoors: Jan 30 Transplant: Mar 6 🍅 Harvest: May 29 – Jul 3
Safe Start (90%) ✓ Fits season (134 days to spare)
Start indoors: Mar 5 Transplant: Apr 9 🍅 Harvest: Jul 2 – Aug 6

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 Humboldt County

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

Soil pH

Your soil pH (6.2–6.8) is within Acorn Squash's preferred range (5.5–7.0).

Soil Texture

Sandy soil in Humboldt County warms quickly in spring but drains fast. Acorn Squash will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Acorn Squash.

How to Plant Acorn Squash

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

Succession Planting Acorn Squash

4
successive plantings in your 274-day season

Sow every 9.1 weeks. Last sowing by Aug 20 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.3″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,866 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 4.8" 0" ❄️ Dormant
Feb 4.8" 5" 0" ✅ Rainfall sufficient
Mar 4.8" 3.3" 1.5" 💧 Light watering
Apr 4.8" 1.7" 3.1" 🚿 Regular watering
May 4.8" 0.5" 4.3" 🚿 Regular watering
Jun 4.8" 0.1" 4.7" 🚿 Regular watering
Jul 4.8" 0" 4.8" 🚿 Regular watering
Aug 4.8" 0" 4.8" 🚿 Regular watering
Sep 4.8" 0.3" 4.5" 🚿 Regular watering
Oct 4.8" 0.8" 4" 🚿 Regular watering
Nov 4.8" 1.9" 2.9" 🚿 Regular watering
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in Humboldt 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 ~1,372 GDD — county provides 4,193 GDD Excellent fit

Acorn Squash Planting Timeline — Humboldt County, CA

Acorn Squash Planting Calendar

Activity When Date Range
Start Indoors January 30 Jan 30 – Feb 13
Transplant Outdoors March 6 Mar 6 – Mar 20
Direct Sow February 27 Feb 27 – Mar 20
Harvest May 29 May 29 – Jul 3

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 2-3 times/week

📅 Days to Maturity

80–100 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 9b

📆 Growing Season

274 days in Humboldt County

Growing Tips for Acorn Squash in Humboldt County

Direct sow Acorn Squash outdoors after February 27 in Humboldt County when soil has warmed and frost danger has passed.

Sandy soil in Humboldt County dries quickly — mulch Acorn Squash with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

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.

Humboldt County receives only 22" 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

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Acorn Squash in Humboldt County, CA?

Humboldt County is in Zone 9b with an average last frost of February 27. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Humboldt County, CA?

Humboldt County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 27 and first fall frost is November 28.

🌱

Your Humboldt County Garden Planner — Free

A 24-page printable planner built for Humboldt County (Zone 9b). 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 Humboldt County, CA. 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.