When to Plant Acorn Squash in Knox County, IL
May in Knox County, Illinois — your action list
A quick May briefing for Knox County, Illinois gardeners — what's urgent, what's next, and what can wait.
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Plant out acorn squash
Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.
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Start acorn squash indoors
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
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.
Knox County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 15, giving you a growing season of approximately 181 days.
At an elevation of 1,301 feet, Knox County receives approximately 33.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Acorn Squash to ensure they mature before fall.
Knox County Soil Profile
Soil Type
Silt Loam
Soil pH
6-6.8
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 Knox County
How your county's soil matches Acorn Squash's growing requirements.
Soil pH
Your soil pH (6.0–6.8) is within Acorn Squash's preferred range (5.5–7.0).
Soil Texture
The silt loam soil in Knox County is excellent for Acorn Squash — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Acorn Squash will thrive.
How to Plant Acorn Squash
Succession Planting Acorn Squash
Sow every 9.1 weeks. Last sowing by Jul 07 to harvest before frost.
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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 4.8" | 3.4" | 1.4" | 💧 Light watering |
| May | 4.8" | 3.9" | 0.9" | 💧 Light watering |
| Jun | 4.8" | 3.6" | 1.2" | 💧 Light watering |
| Jul | 4.8" | 4.1" | 0.7" | 💧 Light watering |
| Aug | 4.8" | 3.5" | 1.3" | 💧 Light watering |
| Sep | 4.8" | 2.6" | 2.2" | 💧 Light watering |
| Oct | 4.8" | 2.7" | 2.1" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Knox 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 — Knox County, IL
Acorn Squash Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 13 | Mar 13 – Mar 27 |
| Transplant Outdoors | May 1 | May 1 – May 15 |
| Direct Sow | April 24 | Apr 24 – May 15 |
| Harvest | July 24 | Jul 24 – Aug 28 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
181 days in Knox County
Growing Tips for Acorn Squash in Knox County
Direct sow Acorn Squash outdoors after April 17 in Knox 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
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Check more plant combinations with our Companion Planting Checker →
Acorn Squash in Other Locations
Frequently Asked Questions
When should I plant Acorn Squash in Knox County, IL?
Knox County is in Zone 5b with an average last frost of April 17. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.
What planting zone is Knox County, IL?
Knox County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 15.
Your Knox County Garden Planner — Free
A 24-page printable planner built for Knox 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.