When to Plant Acorn Squash in San Bernardino County, CA
May in San Bernardino County, California — your action list
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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It's harvest week for acorn squash
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Get ahead of June
- First harvests: 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.
San Bernardino County, California is in USDA Zone 10a. The average last spring frost is February 24 and the first fall frost is November 25, giving you a growing season of approximately 274 days.
At an elevation of 1,012 feet, San Bernardino County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 97°F, so Acorn Squash may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Acorn Squash successfully. Mulch heavily to conserve soil moisture.
San Bernardino County Soil Profile
Soil Type
Loam
Soil pH
5.9-7.2
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 San Bernardino County
How your county's soil matches Acorn Squash's growing requirements.
Soil pH
Your soil pH (5.9–7.2) overlaps with Acorn Squash's range (5.5–7.0), though not a perfect match.
Soil Texture
The loam soil in San Bernardino County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Acorn Squash.
How to Plant Acorn Squash
Succession Planting Acorn Squash
Sow every 9.1 weeks. Last sowing by Aug 17 to harvest before frost.
Plant Water Budget
Water stress score is 10/10 — 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 | — | 3.2" | 0" | ❄️ Dormant |
| Feb | 4.8" | 3.8" | 1" | 💧 Light watering |
| Mar | 4.8" | 2.2" | 2.6" | 🚿 Regular watering |
| Apr | 4.8" | 1.5" | 3.3" | 🚿 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" | 0.2" | 4.6" | 🚿 Regular watering |
| Oct | 4.8" | 0.7" | 4.1" | 🚿 Regular watering |
| Nov | 4.8" | 1.7" | 3.1" | 🚿 Regular watering |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in San Bernardino 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 — San Bernardino County, CA
Acorn Squash Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 27 | Jan 27 – Feb 10 |
| Transplant Outdoors | March 3 | Mar 3 – Mar 17 |
| Direct Sow | February 24 | Feb 24 – Mar 17 |
| Harvest | May 26 | May 26 – Jun 30 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | — |
| 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: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
274 days in San Bernardino County
Growing Tips for Acorn Squash in San Bernardino County
Direct sow Acorn Squash outdoors after February 24 in San Bernardino County when soil has warmed and frost danger has passed.
With summer highs reaching 97°F in San Bernardino County, provide afternoon shade for Acorn Squash and water deeply in the morning.
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.
San Bernardino 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
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Acorn Squash in Other Locations
Frequently Asked Questions
When should I plant Acorn Squash in San Bernardino County, CA?
San Bernardino County is in Zone 10a with an average last frost of February 24. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Bernardino County, CA?
San Bernardino County, California is in USDA Hardiness Zone 10a. The average last spring frost is February 24 and first fall frost is November 25.
Your San Bernardino County Garden Planner — Free
A 24-page printable planner built for San Bernardino County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.