When to Plant Onion in Grundy County, MO
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.
Grundy County, Missouri is in USDA Zone 5b. The average last spring frost is April 14 and the first fall frost is October 18, giving you a growing season of approximately 187 days.
At an elevation of 1,208 feet, Grundy County receives approximately 37.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Onion during the growing season.
Grundy County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.5
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.
Plant Water Budget
Onion Planting Timeline — Grundy County, MO
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 10 | Mar 10 – Mar 24 |
| Transplant Outdoors | April 14 | Apr 14 – Apr 28 |
| Direct Sow | March 31 | Mar 31 – Apr 21 |
| Fall Sowing | August 9 | Aug 9 – Aug 23 |
| Harvest | July 14 | Jul 14 – Sep 1 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| 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
6 – 7
USDA Zone
Zone 5b
Growing Season
187 days
Growing Tips for Grundy 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
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Grundy County, MO?
Grundy County is in Zone 5b with an average last frost of April 14. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grundy County, MO?
Grundy County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 14 and first fall frost is October 18.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Grundy County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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