When to plant Onion in Ogle County, IL
Aim to plant Onion in Ogle County on or after April 9; the window stays open through April 30. Ogle County's 173-day frost-free season gives you a single solid spring crop with a brief fall option. A second sowing from August 4 to August 18 extends the harvest into fall.
When to Plant Onion in Ogle County, IL
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Ogle County, Illinois is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 13, giving you a growing season of approximately 173 days.
At an elevation of 890 feet, Ogle County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Onion during the growing season.
Ogle County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.9
Drainage
Well Drained
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| May | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jun | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Oct | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ogle County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion Planting Timeline — Ogle County, IL
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 19 | Mar 19 – Apr 2 |
| Transplant Outdoors | April 23 | Apr 23 – May 7 |
| Direct Sow | April 9 | Apr 9 – Apr 30 |
| Harvest | July 23 | Jul 23 – Sep 10 |
| Fall Sowing | August 4 | Aug 4 – Aug 18 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 5b
📆 Growing Season
173 days in Ogle County
Growing Tips for Ogle County
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Ogle County, IL?
Ogle County is in Zone 5b with an average last frost of April 23. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ogle County, IL?
Ogle County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 13.
When should I plant Onion in Ogle County, IL?
In Ogle County, IL, plant Onion after the last frost (around April 23) and before the first frost (around October 13). Best results when soil holds above 50°F.
What growing zone is Ogle County, IL for Onion?
Ogle County sits in USDA Zone 5b. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Ogle County's climate?
Yes — Onion grows well in Ogle County's temperate climate. Ogle County averages a 173-day frost-free season, with last frost around April 23 and first frost around October 13.
Your Ogle County Garden Planner — Free
A 22-page printable planner built for Ogle 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.